JAVA_两种比较器的实现

package com.kk.Collection;

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

public class CompareTest {
    public static void main(String[] args) {
        List<Student> list=new ArrayList<Student>(10);
        list.add(new Student(1,"jj"));
        list.add(new Student(0,"ww"));
        list.add(new Student(0,"kk"));
        list.add(new Student(2,"ll"));
        Collections.sort(list); //内部比较器:要排序的对象实现Comparable接口,可以对自身进行比较
        System.out.println(list);
        
        List<Teacher> t=new ArrayList<Teacher>(10);
        t.add(new Teacher(1,12));
        t.add(new Teacher(0,13));
        t.add(new Teacher(0,14));
        t.add(new Teacher(2,15));
        Collections.sort(t,new StudentComparator()); //外部比较器:通过实现Comparator接口
        System.out.println(t);
    }
}

class Student implements Comparable {
    int num;

    String name;

    public Student(int num, String name) {
        this.num = num;
        this.name = name;
    }
    
    @Override
    public String toString() {
        return "\r\tnum:"+num+" name:"+name+"\r";
    }

    public int compareTo(Object o) {
        Student tmp=(Student) o;
        int result=tmp.num>num?1:(tmp.num==num?0:-1);
        if (result==0) {
            result=tmp.name.indexOf(0)>name.indexOf(0)?1:-1;
        }
        return result;
    }
}

class Teacher{
    int num;

    double salary;
    
    public Teacher(int num, double salary) {
        this.num = num;
        this.salary = salary;
    }

    @Override
    public String toString() {
        return "\r\tnum:"+num+" salary:"+salary+"\r";
    }    
}

class StudentComparator implements Comparator{

    public int compare(Object o1, Object o2) {
        Teacher t1=(Teacher) o1;
        Teacher t2=(Teacher) o2;
        int result=t1.num>t2.num?1:(t1.num==t2.num?0:-1);
        return result=result==0?(t1.salary<t2.salary?1:-1):result;
    }
    
}

来源：http://www.cnblogs.com/BigIdiot/archive/2011/12/09/2282673.html