用Java排序多维数组

Question

Please is there a way how to sort multidimensional array in java in the following manner?

Lets have this array structure,

int graph[][] = new int[edges][3];

where every edge will have two coordinates and its weight. And I need to sort the whole array according to the weight of every edge. Just FYI I need it for finding spanning trees. Thanks

Answer 1

You can use something like this:

Arrays.sort(graph, new Comparator<Integer[]>() {
             @Override
             public int compare(final Integer[] entry1, final Integer[] entry2) {
              // DO SORTING STUFF HERE
            } });

Answer 2

I guess you are having problem with using Arrays.sort and Comparator with an array of array . It works similar to what you do in normal Array sorting, with a little change.

This is how you would do this in your case. You need a Comparator for an Integer[] array: -

    Integer graph[][] = new Integer[2][3];
    graph[0][0] = 2;
    graph[0][1] = 4;
    graph[0][2] = 3;

    graph[1][0] = 0;
    graph[1][1] = 1;
    graph[1][2] = 2;


    Arrays.sort(graph, new Comparator<Integer[]>() {
        @Override
        public int compare(Integer[] o1, Integer[] o2) {

            return o1[2] - o2[2];
        }
    });


    for (Integer[] outerArr: graph) {
        for (Integer val: outerArr) {
            System.out.print(val + " ");
        }
        System.out.println();
    }

Prints: -

0 1 2 
2 4 3