public static void main(String[] args){

        int[][] nums=new int[][]{{1,3},{1,2},{4,5},{3,7}};
        //方法一
        Arrays.sort(nums,new Comparator<int[]>(){
            public int compare(int[] a,int[] b){
                if(a[0]==b[0]){
                    return a[1]-b[1];
                }else{
                    return a[0]-b[0];
                }
            }
        });

        //方法二
        /*Arrays.sort(nums,(a,b)->a[0]-b[0]);*/
        for (int[] num : nums) {
            System.out.println(Arrays.toString(num));
        }
    }

[1, 2]
[1, 3]
[3, 7]
[4, 5]

public static void main(String[] args){

        int[][] nums=new int[][]{{1,3},{1,2},{4,5},{3,7}};
        //方法一
        Arrays.sort(nums,new Comparator<int[]>(){
            public int compare(int[] a,int[] b){
                if(a[1]==b[1]){
                    return a[0]-b[0];
                }else{
                    return a[1]-b[1];
                }
            }
        });

        //方法二
        /*Arrays.sort(nums,(a,b)->a[1]-b[1]);*/
        for (int[] num : nums) {
            System.out.println(Arrays.toString(num));
        }
    }

[1, 2]
[1, 3]
[4, 5]
[3, 7]