How to sort an ArrayList?

Question

I have a List of doubles in java and I want to sort ArrayList in descending order.

Input ArrayList is as below:

List<Double> testList = new ArrayList();  testList.add(0.5); testList.add(0.2); testList.add(0.9); testList.add(0.1); testList.add(0.1); testList.add(0.1); testList.add(0.54); testList.add(0.71); testList.add(0.71); testList.add(0.71); testList.add(0.92); testList.add(0.12); testList.add(0.65); testList.add(0.34); testList.add(0.62); 

The out put should be like this

0.92 0.9 0.71 0.71 0.71 0.65 0.62 0.54 0.5 0.34 0.2 0.12 0.1 0.1 0.1 

Answer 1

Collections.sort(testList); Collections.reverse(testList); 

That will do what you want. Remember to import Collections though!

Here is the documentation for Collections.

Answer 2

Descending:

Collections.sort(mArrayList, new Comparator<CustomData>() {     @Override     public int compare(CustomData lhs, CustomData rhs) {         // -1 - less than, 1 - greater than, 0 - equal, all inversed for descending         return lhs.customInt > rhs.customInt ? -1 : (lhs.customInt < rhs.customInt) ? 1 : 0;     } });