about sorting arrays in java

Question

Hi I have 3 arrays (A,B,C) and A has its own integer 10,and C has its own integer 8 and B has its own integer 5 and how can I sort arrays with its integers and then return those arrays?? it means that you sort integers : 5,8,10 and I want to return their arrays : B,C,A how can I do this? please help me thanks

Answer 1

I have found these integers for those arrays and then I sort those arrays with these integers but I do not know that how can I return their arrays?

You can't return 3 objects from a method. Instead, you could put them in an ArrayList in the desired order and return it as List. E.g.:

class MyArrayComparator implements Comparator<int[]> {
    public int compare(int[] a1, int[] a2) {
        int sn1 = getThatSpecialNumber(a1);
        int sn2 = getThatSpecialNumber(a2);
        if (sn1 == sn2)
            return 0;
        else if (sn1 < sn2)
            return -1;
        else
            return 1;
    }
}

List orderArrays(int[] a, int[] b, int[] c) {
    List<int[]> list = new ArrayList<int[]>();

    list.add(a);
    list.add(b);
    list.add(c);
    Collections.sort(list, new MyArrayComparator());
    return list;
}

Answer 2

I'm not sure what do you mean by "has its own integer", but you can store them into i.e. java.util.ArrayList and then search for the value, i.e.:

ArrayList list = new ArrayList();
....
int number_we_are_searching_for = 12345;
int i = 0;
YourArray a = null;
while(i < list.size())
{
    if(list.get(i).SomehowRetrieveThatNumber() == number_we_are_searching_for)
    {
        a = list.get(i);
        break;
    }
    i++;

}

EDIT: Or add them in desired order (sort them while adding).

Answer 3

final int[] a = { 10 }, b = { 5 }, c = { 8 };

// put them in an array. (a List<int[]> works too)
int[][] arrs = { a, b, c };

// sort them using a custom comparator
// (Change "Arrays" to "Collections" if you used a List above)
Arrays.sort(arrs, new Comparator<int[]>() {
    public int compare(int[] o1, int[] o2) {
        return ((Integer) o1[0]).compareTo(o2[0]);
    }
});

// Print result and return it:
for (int[] arr : arrs)
    System.out.println(Arrays.toString(arr));

return arr;

Output:

[5]
[8]
[10]