java怎么对二维数组赋值

<code class="java">int[][] arr = new int[3][4];
arr[0] = new int[]{1, 2, 3, 4};
arr[1] = new int[]{5, 6, 7, 8};
arr[2] = new int[]{9, 10, 11, 12};</code>

<code class="java">int[][] arr = new int[3][4];
for (int i = 0; i < arr.length; i++) {
    for (int j = 0; j < arr[i].length; j++) {
        arr[i][j] = i * arr[i].length + j;
    }
}</code>

<code class="java">int[][] arr1 = new int[2][3];
int[][] arr2 = new int[2][3];

// 行列赋值
arr1[0][0] = 1;
arr1[0][1] = 2;
arr1[0][2] = 3;
arr1[1][0] = 4;
arr1[1][1] = 5;
arr1[1][2] = 6;

// 嵌套循环赋值
for (int i = 0; i < arr2.length; i++) {
    for (int j = 0; j < arr2[i].length; j++) {
        arr2[i][j] = i * arr2[i].length + j;
    }
}

// 打印数组
for (int[] row : arr1) {
    for (int value : row) {
        System.out.print(value + " ");
    }
    System.out.println();
}

for (int[] row : arr2) {
    for (int value : row) {
        System.out.print(value + " ");
    }
    System.out.println();
}</code>

<code>1 2 3
4 5 6
0 1 2
3 4 5</code>