How can you sort a two-dimensional array in Java?

In Java, you can use the sort() method of the Arrays class to sort a two-dimensional array. Here is an example code:

import java.util.Arrays;

public class Main {
    public static void main(String[] args) {
        int[][] arr = {{5, 3, 2}, {9, 7, 1}, {8, 4, 6}};

        // 对二维数组按行排序
        for (int[] row : arr) {
            Arrays.sort(row);
        }
        
        // 对二维数组按列排序
        for (int i = 0; i < arr[0].length; i++) {
            int[] column = new int[arr.length];
            for (int j = 0; j < arr.length; j++) {
                column[j] = arr[j][i];
            }
            Arrays.sort(column);
            for (int j = 0; j < arr.length; j++) {
                arr[j][i] = column[j];
            }
        }

        // 输出排序后的二维数组
        for (int[] row : arr) {
            for (int num : row) {
                System.out.print(num + " ");
            }
            System.out.println();
        }
    }
}

In the code above, the two-dimensional array is first sorted by rows and then by columns. Finally, the sorted two-dimensional array is output.