Charles7c/vitepress-theme-blog-charles7c-s1
Archived
0
0
Fork 0
Code Issues 75 Pull Requests Actions Packages Projects Releases Wiki Activity
This repository has been archived on 2025-06-28. You can view files and clone it, but cannot push or open issues or pull requests.
Files
1302ba19a7a1645c615883e317d00c823bb74597
vitepress-theme-blog-charle…/assets/courses_java_01-Java语法入门_14-多维数组.md.C3Jtu4yX.js

161 lines
85 KiB
JavaScript
Raw Blame History

This file contains invisible Unicode characters

This file contains invisible Unicode characters that are indistinguishable to humans but may be processed differently by a computer. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

import{_ as p}from"./chunks/ArticleMetadata.Sb1DYAHo.js";import{_ as t,D as e,o as h,c as r,I as d,w as g,k as n,a as A,R as C,b as y,e as D}from"./chunks/framework.FVQzxbLi.js";import"./chunks/md5.RtphNWHi.js";const F="/assets/202010091457755.Nuh8VT-X.jpeg",B="/assets/202010091457896.JqZZDNkT.png",c="/assets/202010091458322.5g51bNvB.png",o="/assets/202010091458868.CYjpWfcf.png",E="/assets/202010091458957.OAMLrCAZ.png",u="/assets/202010091459307.e0LUpeP6.png",N=JSON.parse('{"title":"多维数组","description":"","frontmatter":{"title":"多维数组","author":"查尔斯","date":"2020/10/09 15:30","categories":["Java基础快速入门"],"tags":["Java","Java基础"]},"headers":[],"relativePath":"courses/java/01-Java语法入门/14-多维数组.md","filePath":"courses/java/01-Java语法入门/14-多维数组.md","lastUpdated":1661519534000}'),b={name:"courses/java/01-Java语法入门/14-多维数组.md"},m=n("h1",{id:"多维数组",tabindex:"-1"},[A("多维数组 "),n("a",{class:"header-anchor",href:"#多维数组","aria-label":'Permalink to "多维数组"'},"​")],-1),v=C(`<h2 id="前言" tabindex="-1">前言 <a class="header-anchor" href="#前言" aria-label="Permalink to &quot;前言&quot;">​</a></h2><p><strong>C：</strong> 上一篇，我们学习了数组的概念，并掌握了它的定义及基本使用方法。</p><p>下面，我们再来看一个案例需求。</p><p><strong>案例需求：已知有3个班级各5名学员，请计算各个班级的总成绩。</strong></p><p>根据需求及经验来分析，如果我们只是要计算单个班级的学生总成绩，那么定义一个普通数组，来存储这些成绩信息，再去计算即可。</p><div class="language-java vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">java</span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// 存储一个班成绩</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">double</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">[] </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> new</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> double</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">5</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">];</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// ...</span></span></code></pre></div><p>而现在需要计算三个班级的各自总成绩，按经验推导，应该先如下定义存储结构，然后分别计算。</p><div class="language-java vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">java</span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// 存储第一个班成绩</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">double</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">[] </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores1</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> new</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> double</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">5</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">];</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// 存储第二个班成绩</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">double</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">[] </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores2</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> new</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> double</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">5</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">];</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// 存储第三个班成绩</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">double</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">[] </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores3</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> new</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> double</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">5</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">];</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// ...</span></span></code></pre></div><p>自然它也是可以实现需求的。但是，在本篇，笔者将带你学习一种更为高级的方式：多维数组。</p><p><img src="`+F+'" alt="202010091457755"></p><h2 id="概述" tabindex="-1">概述 <a class="header-anchor" href="#概述" aria-label="Permalink to &quot;概述&quot;">​</a></h2><p>上一篇，我们学的用来存储多个数据的数组，它们被称为一维数组。</p><p>多维数组，类似于前面学过的嵌套 if、嵌套循环。笔者觉得，你也可以把多维数组称之为 &quot;嵌套数组&quot;。</p><p>它的常见表现形式有：二维数组、三维数组。</p><div class="tip custom-block"><p class="custom-block-title">笔者说</p><p>二维数组：是以 一维数组 作为 数组元素 的数组，即 “数组的数组”。[1]</p><p>三维数组：是以 二维数组 作为 数组元素 的数组。</p></div><p>有点拗口，定义向绕口令一样，分明就是 &quot;俄罗斯套娃&quot; 么。</p><p><img src="'+B+`" alt="202010091457896"></p><p>不过在使用多维数组前，需要再强化些概念理解：</p><ul><li>一般来讲，主要使用的是二维数组，三维及以上使用较少（ <strong>本篇笔者也主要介绍二维数组的使用</strong> ）</li><li>从语法上来看，Java 支持多维数组的写法</li><li>从内存分配原理的角度上来看，它们都是一维数组而已</li></ul><h2 id="定义" tabindex="-1">定义 <a class="header-anchor" href="#定义" aria-label="Permalink to &quot;定义&quot;">​</a></h2><h3 id="方式一" tabindex="-1">方式一 <a class="header-anchor" href="#方式一" aria-label="Permalink to &quot;方式一&quot;">​</a></h3><p>传统的一维数组的声明和赋值方式，我们都是掌握的：</p><div class="language-java vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">java</span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// 声明语法：数据类型[] 数组名 = new 数据类型[数组容量];</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// 例如：存储5名学生成绩：</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// 数组存储的元素：成绩</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// 数组元素的数据类型：double</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// 数组的容量(要存储的成绩数量)：5</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">double</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">[] </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> new</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> double</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">5</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">];</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// 赋值语法：数组名[下标] = 元素值;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">] </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 90</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">] </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 80</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">] </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 70</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">3</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">] </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 60</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">4</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">] </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 50</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">;</span></span></code></pre></div><p><img src="`+c+`" alt="202010091458322"></p><p>二维数组本质上就是一维数组，只不过是以 一维数组 作为 数组元素 的数组。我们可以把二维数组分成外维数组及内维数组。</p><div class="language-java vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">java</span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// 声明二维数组</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// 语法</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">数据类型[][] 数组名 </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> new</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> 数据类型[外维数组容量][内维数组容量];</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// 给二维数组赋值</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// 语法</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">数组名[外维数组下标][内维数组下标] </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> 元素值;</span></span></code></pre></div><p>我们结合着二维数组的语法，来初步实现下前言中的需求。</p><details class="details custom-block"><summary>案例需求：存储3个班各5名学生成绩。</summary><p><strong>思路分析：</strong></p><ol><li><p>根据需求，由于要存储的两组数据有包含关系，采用二维数组更为合适</p></li><li><p>确定数组的各个组成</p><ul><li><p>外维数组：</p><ul><li><p>数组元素：班级</p></li><li><p>数组元素类型：double[]</p></li><li><p>数组容量：5</p></li></ul></li><li><p>内维数组：</p><ul><li>数组元素：成绩</li><li>数组元素类型：double</li><li>数组容量：3</li></ul></li></ul></li><li><p>根据数组组成，套用方式一的数组语法实现</p></li></ol></details><div class="language-java vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">java</span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// 声明一个二维数组 </span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">double</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">[][] </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> new</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> double</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">3</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">][</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">5</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">];</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// 给二维数组赋值</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// 第1个班</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">][</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">] </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 90</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">; </span><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// 第1个班的第1个同学成绩为90</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">][</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">] </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 80</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">][</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">] </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 70</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">][</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">3</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">] </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 60</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">][</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">4</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">] </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 50</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">;</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// 第2个班</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">][</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">] </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 90</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">][</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">] </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 90</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">][</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">] </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 80</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">][</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">3</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">] </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 70</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">][</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">4</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">] </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 65</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">;</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// 第3个班</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">][</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">] </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 85</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">][</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">] </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 70</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">][</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">] </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 75</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">][</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">3</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">] </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 80</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">][</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">4</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">] </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 60</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">;</span></span></code></pre></div><p><img src="`+o+`" alt="202010091458868"></p><div class="tip custom-block"><p class="custom-block-title">笔者说</p><p>虽然数组有些特别，不像之前学的基本数据类型：int、double..。但数组也是一种数据类型，所以 &quot;别拿豆包不当干粮，别拿数组不当数据类型&quot; 。</p></div><h3 id="方式二" tabindex="-1">方式二 <a class="header-anchor" href="#方式二" aria-label="Permalink to &quot;方式二&quot;">​</a></h3><p>在定义二维数组时，内维数组容量不是必须立刻指定的，还可以这样写。</p><div class="language-java vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">java</span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">数据类型[][] 数组名 </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> new</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> 数据类型[外维数组容量][内维数组容量];</span></span></code></pre></div><p><strong>案例需求：存储三个班学生成绩，1班有5个学生，2班有3个学生，3班有2个学生。</strong></p><div class="language-java vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">java</span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// 声明一个二维数组</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">double</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">[][] </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> new</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> double</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">3</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">][];</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// 声明内维数组</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">] </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> new</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> double</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">5</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">]; </span><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// 第一个班</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">] </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> new</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> double</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">3</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">]; </span><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// 第二个班</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">] </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> new</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> double</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">]; </span><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// 第三个班</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// 赋值语法：数组名[外维数组下标][内维数组下标] = 元素值;</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// 第1个班</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">][</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">] </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 90</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">][</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">] </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 80</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">][</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">] </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 70</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">][</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">3</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">] </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 60</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">][</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">4</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">] </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 50</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">;</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// 第2个班</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">][</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">] </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 90</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">][</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">] </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 90</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">][</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">] </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 80</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">;</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// 第3个班</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">][</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">0</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">] </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 85</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">2</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">][</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">] </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 70</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">;</span></span></code></pre></div><p><img src="`+E+`" alt="202010091458957"></p><h3 id="方式三" tabindex="-1">方式三 <a class="header-anchor" href="#方式三" aria-label="Permalink to &quot;方式三&quot;">​</a></h3><p>一维数组可以在声明时，实现直接赋值，二维数组自然也是可以的。</p><div class="language-java vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">java</span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// 存储3个班各5名同学成绩</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// 每个 {} 就是一个一维数组</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">double</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">[][] </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> {{</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">90</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">80</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">70</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">60</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">50</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">}, {</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">90</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">90</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">80</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">70</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">65</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">}, {</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">85</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">70</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">75</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">80</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">60</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">}};</span></span></code></pre></div><p>另外它也支持下方的写法：</p><div class="language-java vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">java</span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">double</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">[][] </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> new</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> double</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">[][]{{</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">90</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">80</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">70</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">60</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">50</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">}, {</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">90</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">90</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">80</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">70</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">65</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">}, {</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">85</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">70</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">75</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">80</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">60</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">}};</span></span></code></pre></div><h2 id="动态赋值及遍历" tabindex="-1">动态赋值及遍历 <a class="header-anchor" href="#动态赋值及遍历" aria-label="Permalink to &quot;动态赋值及遍历&quot;">​</a></h2><p>一维数组学习的时候，我们发现在数组赋值时是重复性、有规律性的。当时我们就用 Scanner 结合循环来优化了一下赋值过程，这样就拥有了动态赋值的能力。</p><p>现在二维数组赋值虽然更为复杂，但是依然保有重复性、规律性，我们也可以用 Scanner 结合循环来优化一下。</p><p><img src="`+u+`" alt="202010091459307"></p><p><strong>思路分析：</strong></p><ol><li>根据效果图分析，它分别有两个规律性操作，采用二重循环 <ul><li>班级的规律</li><li>每个班级的规律</li></ul></li><li>循环要素 <ul><li><p>外层循环</p><ul><li>循环条件：<code>&lt; 外维数组的容量</code></li><li>循环操作：内层循环</li></ul></li><li><p>内层循环</p><ul><li>循环条件：<code>&lt; 内维数组的容量</code></li><li>循环操作： 数组名[外层循环变量][内层循环变量] = 输入的元素值;</li></ul></li></ul></li><li>固定次数循环，采用 for 循环</li><li>检查循环是否可以正常退出</li></ol><div class="language-java vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">java</span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">double</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">[][] </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> new</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> double</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">[</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">3</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">][</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">5</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">];</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">Scanner</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> input</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> new</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;"> Scanner</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(System.in);</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// 循环班级</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">for</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> (</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">int</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> i</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 0</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">; i </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">&lt;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> scores.length; i</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">++</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">) {</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 循环每个班级</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> System.out.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">println</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&quot;开始录入第&quot;</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> +</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> (i</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">+</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">+</span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;"> &quot;个班的学生成绩：&quot;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">);</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> for</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> (</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">int</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> j</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 0</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">; j </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">&lt;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> scores[i].length; j</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">++</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">) {</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> System.out.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">print</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&quot;请输入&quot;</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> +</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> (i</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">+</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">+</span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;"> &quot;班的第&quot;</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> +</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> (j</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">+</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">+</span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;"> &quot;个学生的成绩：&quot;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">);</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> scores[i][j] </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> input.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">nextDouble</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">();</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> }</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">}</span></span></code></pre></div><p>上述代码就是二维数组的动态赋值方式。如果去除输入赋值环节后，它显然又是二维数组的遍历方式。</p><div class="language-java vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">java</span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">double</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">[][] </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> {{</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">90</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">80</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">70</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">60</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">50</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">}, {</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">90</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">90</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">80</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">70</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">65</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">}, {</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">85</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">70</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">75</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">80</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">60</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">}};</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// 循环班级</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">for</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> (</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">int</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> i</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 0</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">; i </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">&lt;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> scores.length; i</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">++</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">) {</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 循环每个班级</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> System.out.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">println</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">((i</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">+</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">+</span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;"> &quot;班的学生成绩如下：&quot;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">);</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> for</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> (</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">int</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> j</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 0</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">; j </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">&lt;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> scores[i].length; j</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">++</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">) {</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> System.out.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">println</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&quot;第&quot;</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> +</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> (j</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">+</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">+</span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;"> &quot;个学生的成绩是：&quot;</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> +</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> scores[i][j]);</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> }</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">}</span></span></code></pre></div><p><strong>控制台输出：</strong></p><div class="language- vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang"></span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span>1班的学生成绩如下：</span></span>
<span class="line"><span>第1个学生的成绩是：90.0</span></span>
<span class="line"><span>第2个学生的成绩是：80.0</span></span>
<span class="line"><span>第3个学生的成绩是：70.0</span></span>
<span class="line"><span>第4个学生的成绩是：60.0</span></span>
<span class="line"><span>第5个学生的成绩是：50.0</span></span>
<span class="line"><span>2班的学生成绩如下：</span></span>
<span class="line"><span>第1个学生的成绩是：90.0</span></span>
<span class="line"><span>第2个学生的成绩是：90.0</span></span>
<span class="line"><span>第3个学生的成绩是：80.0</span></span>
<span class="line"><span>第4个学生的成绩是：70.0</span></span>
<span class="line"><span>第5个学生的成绩是：65.0</span></span>
<span class="line"><span>3班的学生成绩如下：</span></span>
<span class="line"><span>第1个学生的成绩是：85.0</span></span>
<span class="line"><span>第2个学生的成绩是：70.0</span></span>
<span class="line"><span>第3个学生的成绩是：75.0</span></span>
<span class="line"><span>第4个学生的成绩是：80.0</span></span>
<span class="line"><span>第5个学生的成绩是：60.0</span></span></code></pre></div><div class="tip custom-block"><p class="custom-block-title">笔者说</p><p>一维数组的时候，我们有两种遍历方式：1.循环下标遍历 2.增强 for循 环遍历。而二维数组的话，笔者建议你就采用循环下标方式即可，不要再去 &quot;混合或者自造语法&quot; 了。</p></div><h2 id="使用" tabindex="-1">使用 <a class="header-anchor" href="#使用" aria-label="Permalink to &quot;使用&quot;">​</a></h2><p>好了，介绍完二维数组的概念和定义方式，接下来我们完整的使用它，来完成前言中的案例需求。</p><p><strong>案例需求：已知有3个班级各5名学员，请使用二维数组计算各个班级的总成绩。</strong></p><div class="language-java vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">java</span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">double</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">[][] </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">scores</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> {{</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">90</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">80</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">70</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">60</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">50</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">}, {</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">90</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">90</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">80</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">70</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">65</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">}, {</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">85</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">70</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">75</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">80</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">60</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">}};</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// 循环班级</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// 定义变量，记录每个班的总成绩</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">double</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> sum;</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">for</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> (</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">int</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> i</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 0</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">; i </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">&lt;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> scores.length; i</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">++</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">) {</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 每次都要初始化总成绩</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> sum </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 0</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">; </span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 循环每个班级</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> for</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> (</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">int</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> j</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 0</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">; j </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">&lt;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> scores[i].length; j</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">++</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">) {</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 累加成绩</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> sum </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">+=</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> scores[i][j];</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> }</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> System.out.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">println</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">((i</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">+</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">+</span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;"> &quot;班的学生总成绩为：&quot;</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> +</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> sum);</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">}</span></span></code></pre></div><p><strong>控制台输出：</strong></p><div class="language- vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang"></span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span>1班的学生总成绩为：350.0</span></span>
<span class="line"><span>2班的学生总成绩为：395.0</span></span>
<span class="line"><span>3班的学生总成绩为：370.0</span></span></code></pre></div><h2 id="arrays工具类" tabindex="-1">Arrays工具类 <a class="header-anchor" href="#arrays工具类" aria-label="Permalink to &quot;Arrays工具类&quot;">​</a></h2><p>有了数组之后，我们就可以实现非常多的算法需求。但很多算法需求中，部分功能都是类似的，我们重复的实现，重复的写。</p><p><strong>例如：遍历输出数组的所有内容。</strong></p><div class="language-java vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">java</span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">String</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">[] </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">arr</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> {</span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&quot;佩奇&quot;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&quot;乔治&quot;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&quot;苏西&quot;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">};</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// 循环下标来实现数组遍历</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">for</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> (</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">int</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> i</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 0</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">; i </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">&lt;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> arr.length; i</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">++</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">) {</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> System.out.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">println</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(arr[i]);</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">}</span></span></code></pre></div><p>而这一切，Java 创造团队们也考虑到了，他们给我们在 Java 类库中提供了一个工具类：<code>Arrays</code>。在这个类中，提供的都是操作数组的方法。</p><table><thead><tr><th style="text-align:left;"><strong>方法名称</strong></th><th><strong>说明</strong></th></tr></thead><tbody><tr><td style="text-align:left;">toString(array) : String</td><td>将一个数组 array 转换成一个字符串</td></tr><tr><td style="text-align:left;">equals(array1,array2) : boolean</td><td>比较 array1 和 array2 两个数组是否相等</td></tr><tr><td style="text-align:left;">sort(array) : void</td><td>对数组 array 的元素进行升序排列</td></tr><tr><td style="text-align:left;">copyOf(array,length) : newArray</td><td>把数组 array 复制成一个长度为 length 的新数组，返回类型与复制的数组一致</td></tr><tr><td style="text-align:left;">...</td><td>...</td></tr></tbody></table><p>它和我们曾经使用过的 Scanner 都在 <code>java.util</code> 包下，所以使用的话也需要先导入一下。</p><div class="tip custom-block"><p class="custom-block-title">笔者说</p><p>Java 系统类库 java.util 包下的类都是工具类，使用前需要先 import。</p></div><p>看看下方，有了 Arrays，你只需要一行代码，就可以搞定一个数组的遍历输出操作。</p><div class="language-java vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">java</span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">package</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> demo1;</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// 1.导入 Arrays</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">import</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> java.util.Arrays;</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">public</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> class</span><span style="--shiki-light:#6F42C1;--shiki-dark:#F69D50;"> Demo1</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> {</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> public</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> static</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> void</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;"> main</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">String</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">[] </span><span style="--shiki-light:#E36209;--shiki-dark:#F69D50;">args</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">) {</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> String</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">[] </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">arr</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> {</span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&quot;佩奇&quot;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&quot;乔治&quot;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&quot;苏西&quot;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">};</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;"> // 2.使用 Arrays(它不需要创建对象，直接可以用)</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> String</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> arrStr</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Arrays.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">toString</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(arr);</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> System.out.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">println</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(arrStr); </span><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// [佩奇, 乔治, 苏西]</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> }</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">}</span></span></code></pre></div><p><strong>再例如：要比较两个数组的内容是否相同。</strong></p><div class="language-java vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">java</span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">char</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">[] </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">charArr1</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> {</span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&#39;a&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&#39;b&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&#39;c&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&#39;d&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">};</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">char</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">[] </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">charArr2</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> {</span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&#39;a&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&#39;b&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&#39;c&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&#39;d&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">};</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// 不使用 equals 方法，原生写法</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">boolean</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> flag</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> true</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">;</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">for</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> (</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">int</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> i</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 0</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">; i </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">&lt;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> charArr1.length; i</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">++</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">) {</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> if</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> (charArr1[i] </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">!=</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> charArr2[i]) {</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> flag </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> false</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> }</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">}</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">System.out.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">println</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&quot;两个数组内容是否一致？&quot;</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> +</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> flag);</span></span></code></pre></div><p>而有了 Arrays，你只需要一行代码，就可以搞定两个数组的内容比较操作。</p><div class="language-java vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">java</span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">char</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">[] </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">charArr1</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> {</span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&#39;a&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&#39;b&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&#39;c&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&#39;d&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">};</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">char</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">[] </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">charArr2</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> {</span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&#39;a&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&#39;b&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&#39;c&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&#39;d&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">};</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">boolean</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> flag</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Arrays.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">equals</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(charArr1, charArr2);</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">System.out.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">println</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#96D0FF;">&quot;两个数组内容是否一致？&quot;</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> +</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> flag);</span></span></code></pre></div><p>我们再来看看另外两个方法的使用示例。</p><div class="language-java vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">java</span><pre class="shiki shiki-themes github-light github-dark-dimmed vp-code"><code><span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// sort 方法</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">int</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">[] </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">arr1</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> {</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">10</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">9</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">11</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">7</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">8</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">};</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">Arrays.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">sort</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(arr1);</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">System.out.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">println</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(Arrays.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">toString</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(arr1)); </span><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// [7, 8, 9, 10, 11]</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// copyOf 方法</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">int</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">[] </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">arr2</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> {</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">10</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">9</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">11</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">7</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">, </span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;">8</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">};</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">int</span><span style="--shiki-light:#24292E;--shiki-dark:#F69D50;">[] </span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">newArr</span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;"> Arrays.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">copyOf</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(arr2, arr2.length </span><span style="--shiki-light:#D73A49;--shiki-dark:#F47067;">+</span><span style="--shiki-light:#005CC5;--shiki-dark:#6CB6FF;"> 1</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">);</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">System.out.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">println</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(Arrays.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#DCBDFB;">toString</span><span style="--shiki-light:#24292E;--shiki-dark:#ADBAC7;">(newArr)); </span><span style="--shiki-light:#6A737D;--shiki-dark:#768390;">// [10, 9, 11, 7, 8, 0]</span></span></code></pre></div><div class="tip custom-block"><p class="custom-block-title">笔者说</p><p>Arrays 工具类还有更多的数组操作方法，等以后需要使用时，笔者再告诉你。或者在未来你有需求时，也可以去查阅 Java 官方的 API 文档，来挑选适合你的数组操作方法。</p></div><h2 id="答题环节" tabindex="-1">答题环节 <a class="header-anchor" href="#答题环节" aria-label="Permalink to &quot;答题环节&quot;">​</a></h2><h3 id="统计销售额" tabindex="-1">统计销售额 <a class="header-anchor" href="#统计销售额" aria-label="Permalink to &quot;统计销售额&quot;">​</a></h3><p><strong>需求：统计一个公司三个销售小组中每个小组的 总销售额 以及 整个公司的销售额 。</strong></p><ol><li><p>定义一个二维数组，存储三个销售小组的销售额。</p></li><li><p>第一小组销售额为{5, 10}万元，第二小组销售额为{10, 20, 30}万元，第三小组销售额为{10, 10, 20, 20}万元。</p></li><li><p>计算每个小组的总销售额和整个公司的销售额并输出。</p></li></ol><h2 id="参考文献" tabindex="-1">参考文献 <a class="header-anchor" href="#参考文献" aria-label="Permalink to &quot;参考文献&quot;">​</a></h2><p>[1]百度百科. 二维数组[EB/OL]. <a href="https://baike.baidu.com/item/%E4%BA%8C%E7%BB%B4%E6%95%B0%E7%BB%84/8168543" target="_blank" rel="noreferrer">https://baike.baidu.com/item/二维数组/8168543</a>. 2021.1.17</p><h2 id="后记" tabindex="-1">后记 <a class="header-anchor" href="#后记" aria-label="Permalink to &quot;后记&quot;">​</a></h2><p>这一篇，咱们还学到了一个 Arrays 工具类，是不是感觉一些数组操作也没那么难了？的确，有了这类工具类的加入，将会更方便我们日常的需求实现。</p><p>但也别忘了自身内功的提升，如果以后没有合适的工具类，难道我们就不能自己写出来了吗？</p><p>下一篇，我们将围绕数组进行一些排序算法学习，毕竟数据结构和算法不分家，算法中又以排序算法最为经典，期待一下吧。</p><div class="info custom-block"><p class="custom-block-title">笔者说</p><p>对于技术的学习，笔者一贯遵循的步骤是：先用最最简单的 demo 让它跑起来，然后学学它的最最常用 API 和 配置让自己能用起来，最后熟练使用的基础上，在空闲时尝试阅读它的源码让自己能够洞彻它的运行机制，部分问题出现的原因，同时借鉴这些技术实现来提升自己的代码高度。</p><p>所以在笔者的文章中，前期基本都是小白文，仅仅穿插很少量的源码研究。当然等小白文更新多了，你们还依然喜欢，后期会不定时专门对部分技术的源码进行解析。</p></div>`,88);function q(s,f,j,_,S,x){const k=p,l=e("ClientOnly");return h(),r("div",null,[m,d(l,null,{default:g(()=>{var i,a;return[(((i=s.$frontmatter)==null?void 0:i.aside)??!0)&&(((a=s.$frontmatter)==null?void 0:a.showArticleMetadata)??!0)?(h(),y(k,{key:0,article:s.$frontmatter},null,8,["article"])):D("",!0)]}),_:1}),v])}const T=t(b,[["render",q]]);export{N as __pageData,T as default};
Reference in New Issue View Git Blame Copy Permalink