Java 7 sorting.

CommentFun.java

package hello;

import java.util.ArrayList;
import java.util.Comparator;
import java.util.List;


public class CommentFun
{

    public static void main(String[] args)
    {
        Comment c1 = new Comment(1, "joe", "hello", "my comment 1");
        Comment c2 = new Comment(2, "bob", "hello", "my comment 2");
        Comment c3 = new Comment(3, "bill", "hello", "my comment 3");
        Comment c4 = new Comment(4, "mary", "hello", "my comment 3");

        List<Comment> comments = new ArrayList<>();
        comments.add(c2);
        comments.add(c3);
        comments.add(c1);
        comments.add(c4);
        
        
        comments.sort(new Comparator<Comment>() {
            public int compareIds(Integer id1, Integer id2) {
                return id1.compareTo(id2);
            }
            
            @Override
            public int compare(Comment c1, Comment c2) {
                //return c2.getAuthor().compareTo(c1.getAuthor());
                return compareIds(c2.getId(), c1.getId());
            }
            
        });
        
        for (Comment comment: comments) {
            System.out.println("*"+ comment.getId() + ": " + comment.getAuthor());
        }

    }
}