学习Java. 基础 17: 二维数组

深藏阁楼爱情的钟 2023-02-24 11:09 29阅读 0赞

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# 概念 #

二维数组: 大数组里每个元素都是小数组

之前学习的一维数组: 数组里每个元素 都是正常值

// 一班
    String [] java1 = {"赵海棠","咖喱酱"};
    //二班
    String [] java2 = {"胡一菲","曾小贤"};
    //三班
    String [] java3 = {"吕子乔","吕嘉一","陈美嘉"};
    //四班
    String [] java4 = {"张伟","诸葛大力"};
    //五班
    String [] java5 = {"关谷神奇","唐悠悠"};
    //六班
    String [] java6 = {"陆展博","林宛瑜"};
    //七班
    String [] java7 = {"Lisa榕","小黑","诺澜","秦羽墨","杜俊","张三峰","沈临风","苑春丽","黄宝强","小月月","乔伊"};
    
    /*
    把上面的所有数组, 合并成一个数组
    为了减少定义变量
    二维数组: 数组里保存元素---数组
    */
    String [][] java = {
    	{"赵海棠","咖喱酱"},
    	{"胡一菲","曾小贤"},
    	{"吕子乔","吕嘉一","陈美嘉"},
    	{"张伟","诸葛大力"},
    	{"关谷神奇","唐悠悠"},
    	{"陆展博","林宛瑜"},
    	{"Lisa榕","小黑","诺澜","秦羽墨","杜俊","张三峰","沈临风","苑春丽","黄宝强","小月月","乔伊"}
    };

# 格式 #

int [][] 数组名 = {
    	小数组1,
    	小数组2,
    	......
    	小数组N
    };

# 元素获取 #

大索引：是编号为几的小数组
    小索引：是编号为几的小数组内的元素
    获取：**arr[大索引][小索引]**
    赋值：**arr[大索引][小索引] = 值;**

![up-bb5c79336cfda29e69a70ba34815a6d141e.png][]

# 二维数组遍历 #

二维数组（小数组）每个元素，依次取出来
    int[][] arr = {
     {1,2,3},
     {4,5,6},
     {7,8,9}
    };

![up-953a6365de9547d729275fc79be48bda229.png][]

## 格式 ##

for(int i = 0;){
    	arr[i] 某个小数组
    	for(int j = 0;){
    		arr[i][j] 某个小数组中某个元素
    	}
    }

## 入门 ##

![up-35c067d600b08cacbc1760727ccd3e7f4b3.png][]

## 进阶 ##

![up-ac99261f682704c53e73b9428a748f42c14.png][]

# 二维数组的其它定义格式 #

## 格式二: ##

**数据类型\[\]\[\] 数组名 = new 数据类型\[大数组长度\]\[小数组长度\]**

![up-20518a474a9cbd28b013b98012db941dde1.png][]

## 格式三: ##

**数据类型\[\]\[\] 数组名 = new 数据类型\[大数组长度\]\[\];**

![up-68616ea30d82ea782b787a3c4a736ac2b6e.png][]

# 二维数组应用场景 #

Excel表格：统计，累加，最大值，最小值，平均值

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