java自定義比較器Comparator

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


public class User {
	private String username;
	private int gametimes;
	private int succtimes;
	public String getUsername() {
		return username;
	}
	public void setUsername(String username) {
		this.username = username;
	}
	public int getGametimes() {
		return gametimes;
	}
	public void setGametimes(int gametimes) {
		this.gametimes = gametimes;
	}
	public int getSucctimes() {
		return succtimes;
	}
	public void setSucctimes(int succtimes) {
		this.succtimes = succtimes;
	}
	
	public double getSuccRate() {
		if(gametimes == 0) {
			return 0;
		}
		return (double)succtimes / gametimes;
	}

	public static void main(String[] args) {
		List<User> list = new ArrayList<User>();
		User user = new User();
		user.setUsername("1");
		user.setGametimes(0);
		user.setSucctimes(0);
		User user2 = new User();
		user2.setUsername("2");
		user2.setGametimes(3);
		user2.setSucctimes(2);
		list.add(user);
		list.add(user2);
		for(User user3 : list) {
			System.out.println(user3.getUsername());
		}
		Collections.sort(list, new Comparator<User>() {

			@Override
			public int compare(User o1, User o2) {
				double a = o1.getSuccRate();
				double b = o2.getSuccRate();
				System.out.println(a);
				System.out.println(b);
				return new Double(b).compareTo(new Double(a));
			}
		});
		for(User user3 : list) {
			System.out.println(user3.getUsername());
		}
		
	}
	
}