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接口,类型参数T通常设为实现该接口的类名
* 实现Comparable接口后,还要覆盖public int compareTo( 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{
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 points=new ArrayList();
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);
}
}
结果
true
[[1,6], [3,4], [5,2]]
排序后的情况
[[3,4], [5,2], [1,6]]