多维数组——Java

可以认为二维数组是元素为一维数组的数组

type[][] arrayName;

arrayName = new type[][]{{...}, {...}, ...};
- 若在声明时直接进行初始化，则可以省略new type[][]
- type[][] arrayName = {{...}, {...}, ...};

arrayName = new type[outerLength][innerLength];

- 访问元素：arrayName[outerIndex][innerIndex]
- 访问长度：arrayName.length, arrayName[outerIndex].length

package mulArray;

import java.util.Arrays;

public class app {
    public static void main(String[] args) {
        // 静态初始化
        int[][] arr1 = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}};
        System.out.println(Arrays.toString(arr1));
        System.out.println(Arrays.deepToString(arr1));

        // 动态初始化
        int[][] arr2 = new int[5][2];
        for (int i = 0; i < arr2.length; ++i) {
            for(int j = 0; j < arr2[i].length; ++j) {
                arr2[i][j] = (int) (Math.random() * 100 + 1);
            }
        }

        System.out.println(Arrays.deepToString(arr2));

        // 遍历二维数组
        for (int i = 0; i < arr1.length; ++i) {
            for(int j = 0; j < arr1[i].length; ++j){
                System.out.print(arr1[i][j] + "t");
            }
            System.out.println("");
        }
        // 本质是一维的
        // 用动态的方式初始化的时候，外层的长度是一定要给的，内层数组的长度不指定可以
        int[][] arr3 = new int[3][];
        // 接着将它当成一维数组，给每个索引的位置去赋值
        arr3[0] = new int[] {1, 6};
        arr3[1] = new int[] {5, 63, 96, 36, 33};
        arr3[2] = new int[] {11, 66};
        System.out.println(Arrays.deepToString(arr3));

        System.out.println("层行列");
        // 更多的维度
        int[][][] arr4 = {
                {{1, 2, 6}, {2, 9}, {33}},
                {{11}, {33, 22, 69}},
                {{22}}
        };
        
        for (int i = 0; i < arr4.length; ++i) {
            for (int j = 0; j < arr4[i].length; ++j) {
                for (int k = 0; k < arr4[i][j].length; ++k) {
                    System.out.print(arr4[i][j][k] + "t");
                }
                System.out.println(' ');
            }
            System.out.println(' ');
        }

    }


}