[Java array learning] two-dimensional array

Multidimensional Arrays

A multi-dimensional array can be regarded as an array of arrays. For example, a two-dimensional array is a special one-dimensional array, each element of which is a one-dimensional array.

Two-dimensional array

int[][] a = new int[2][4]   //定义一个两行四列的数组

public static void main(String[] args) {
    
    
    int[][] arrays;
    arrays =new int[4][2];//四行二列的数组
    arrays[0][0]=1;
    arrays[0][1]=2;
    arrays[1][0]=3;
    arrays[1][1]=4;
    arrays[2][0]=5;
    arrays[2][1]=6;
    arrays[3][0]=7;
    arrays[3][1]=8;

    for (int i = 0; i < arrays.length; i++) {
    
    
        for (int j = 0; j < arrays[i].length; j++) {
    
    
            System.out.print(arrays[i][j]+" ");
        }  System.out.println("");、
    }
    /*输出结果为：
      1 2 
      3 4 
      5 6 
      7 8 
      */

Related basic applications:

public static void main(String[] args) {
    
    
    /*[3][2],三行两列的数组：
    1,2   arrays[0]
    3,4   arrays[1]
    5,6   arrays[2]
     */
    int[][] arrays = {
    
    {
    
    1,2},{
    
    3,4},{
    
    5,6}};

    //1.1输出arrays[0]
    for (int i : arrays[0]) {
    
    
        System.out.println(i);
    }
    //1.2或者方法二：
    for (int i = 0; i < arrays[0].length; i++) {
    
    
        System.out.println(arrays[0][i]);
    }
    //1.3或者方法三 调用方法：
    printArray(arrays[0]);
    //1.4或者方法四，最简单的直接打印
    System.out.println("==============================");
    System.out.println(arrays[0][0]);//单个元素表示方法arrays[][]
    System.out.println(arrays[0][1]);


    System.out.println("==============================");
    //2.1获取数组长度
    System.out.println(arrays.length);//结果为3
    System.out.println(arrays[0].length);//结果为2


    System.out.println("==============================");
    //3.1输出二维数组所有元素
    for (int i = 0; i < arrays.length; i++) {
    
    
        for (int j = 0; j < arrays[i].length; j++) {
    
    
            System.out.println(arrays[i][j]);

        }

        }
    }

public static void printArray(int[] arrays){
    
    
    for (int i = 0; i < arrays.length; i++) {
    
    
        System.out.println(arrays[i]);
    }
}