常用类API-Compare、Comparator

 

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



public class fuxi6_compare
{
    public static void main(String[] args)
    {
        ArrayList<Students> list = new ArrayList<Students>();
        list.add(new Students("acc", 28));
        list.add(new Students("aa", 20));
        list.add(new Students("ddd", 25));
        list.add(new Students("eee", 22));
        list.add(new Students("fff", 26));
        list.add(new Students("ggg", 23));


        Collections.sort(list);  //直接对students对象排序

        Caipan caipan = new Caipan();   //创建裁判对象
        Collections.sort(list,caipan);  //根据裁判来排序
        System.out.println(list);

    }
}

/**
 *
 *直接实现比较接口，重写compareTo方法
*/
class Students implements Comparable<Students>  //记得添加泛型
{
    String name;
    int age;
    public Students(String name,int age)
    {
        this.name = name;
        this.age = age;
    }
    @Override
    public int compareTo(Students o)  //重写compareTo，返回值负数、0、正数判断大小
    {
        return o.age - this.age;  //由大到小排列
    }

    /**
     * 名字按字母顺序排列，直接调用compareTo方法比较即可
     */
//  @Override
//  public int compareTo(Person o)
//  {
//      return this.name.compareTo(o.name);
//  }
    @Override
    public String toString()
    {
        return "Students [name=" + name + ", age=" + age + "]";
    }
}



/**
 * 创建一个裁判来进行比较,裁判需要实现Comparator
 */

class Caipan implements Comparator<Students>//必须添加泛型
{
    @Override
    public int compare(Students stu1, Students stu2)
    {
        return stu1.age - stu2.age;
    }
}

class Students
{
    String name;
    int age;
    public Students(String name,int age)
    {
        this.name = name;
        this.age = age;
    }
    @Override
    public String toString()
    {
        return "Students [name=" + name + ", age=" + age + "]";
    }

}

 

本文出自 “天空没有痕迹但我飞过” 博客，转载请与作者联系！