Java的比较器

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;    }

}

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