how to sort an ArrayList in ascending order using Collections and Comparator

Question

How to sort an ArrayList in ascending order using Comparator? I know how to sort it in descending order using:

Comparator mycompar         


        

Answer 1

Use the default version:

Collections.sort(myarrayList);

Of course this requires that your Elements implement Comparable, but the same holds true for the version you mentioned.

BTW: you should use generics in your code, that way you get compile-time errors if your class doesn't implement Comparable. And compile-time errors are much better than the runtime errors you'll get otherwise.

List list = new ArrayList();
// now fill up the list

// compile error here unless MyClass implements Comparable
Collections.sort(list);