sort.java

import java.util.Arrays;
import java.util.Collections;
import java.util.List;

public class CustomComparator {
	public static void main(String[] args) {
		String[] names = {"bba", "b", "aaaa", "ccc"};		
		List<String> name_list = Arrays.asList(names);
		System.out.println("Before : "+Arrays.toString(name_list.toArray()));

		Collections.sort(
			name_list, (a,b) -> 
			a.length() < b.length() ? -1 : a.length() == b.length() ? 0 : 1
		);
		 //return 1 if a should be before b 
		 //return -1 if a should be before b
		 //return 0 otherwise

		System.out.println("After : "+Arrays.toString(name_list.toArray()));
	}
}