ArrayList sorting on the basis of object property [duplicate]

Answer 1

You can use the Collections.sort method with a custom Comparator:

 import java.util.Collections;
 import java.util.Comparator;

 [...]

 Collections.sort(empList, new Comparator() {
                @Override public int compare(Employee x, Employee y) {
                   return Integer.compare(x.getAge(), y.getAge());
                }
            });

I used anonymous Comparator class, you can also write an ordinary Comparator class, see Sri Harsha Chilakapati answer.