Java中的Sort String []数组列表

Question

I have a ArrayList<String[]> .

example element:

test,400000,30

So the Array list contains this type of String arrays. Lets divide last value by middle value in one array. so it will be like this.

30/400000 = 0.000075

I need to sort the array list by these values (lastvalue/middlevalue) in ascending order.

How can I do that?

Answer 1

You can write your custom Comparator :

public class StringArrayComparator implements Comparator<String[]> {
    @Override
    public int compare(String[] a, String[] b) {
        double aVal = Double.valueOf (a[2]) / Double.valueOf (a[1]);
        double bVal = Double.valueOf (b[2]) / Double.valueOf (b[1]);

        return Double.compare(aVal, bVal);
    }
}

And then use it with Collections.sort :

List<String[]> myList = /* some value */;
Collections.sort(myList, new StringArrayComparator());

Note:
This implementation assumes valid input - that all the arrays are (at least) three elements long, that the second and third elements are parsable to integers, and that the second element (which we divide by) isn't zero.