java 类比较大小（实现Comparable接口）

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

/**
* 两个类要想比较大小，
* 就必须实现Comparable<T>接口，类型参数T通常设为实现该接口的类名
* 实现Comparable<T>接口后，还要覆盖public int compareTo(<T> object)方法
*		如果两个对象相等返回0
*		当前对象大于方法传过来的对象时，返回一个正整数
*      当前对象小于方法传过来的对象时，返回一个负整数
*		而且相等时必须和equals()方法保持一致，即eaquls()方法要返回true
*		否则相反
*/
public class comparablePoint implements Comparable<comparablePoint>{
public int x;
public int y;
public comparablePoint(int x,int y)
{
this.x=x;
this.y=y;
}
public int compareTo(comparablePoint point)
{
int s1=x*x+y*y;
int s2=point.x-point.x+point.y*point.y;
return s1-s2;
}
public String toString()
{
return "["+x+","+y+"]";
}
public static void main(String args[])
{
if(new comparablePoint(3, 4).compareTo(new comparablePoint(1, 1))>0)
System.out.println("true");
//线性表
List<comparablePoint> points=new ArrayList<comparablePoint>();
points.add(new comparablePoint(1, 6));
points.add(new comparablePoint(3, 4));
points.add(new comparablePoint(5, 2));
System.out.println(points);
Collections.sort(points);//调用Collections工具类进行排序
System.out.println("排序后的情况");
System.out.println(points);
}
}