java中Comparator比较器的使用

java中Comparator的使用：对用户集合进行排序，先按照年龄大小排序，若年龄相等，则按照姓名排序

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public int compare(User u1, User u2) {}

此方法返回一个int类型的数据，但是此int的值只能是一下三种：

1：表示大于

-1：表示小于

0：表示相等

例：   从小到大的顺序排列

public class FielNameComparator implements Comparator {    @Override    public int compare(Object o1, Object o2) {        String fileName1 = (String) o1;        String fileName2 = (String) o2;        String[] aa1 = fileName1.split(".xml")[0].split("_");        String b1 = aa1[aa1.length - 1];        long l1 = Long.parseLong(b1);        String[] aa2 = fileName2.split(".xml")[0].split("_");        String b2 = aa2[aa2.length - 1];        long l2 = Long.parseLong(b2);        if(l1<l2) {            return -1;        }else if(l1>l2) {            return 1;        }        return 0;    }}

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package com.mango.compare;

 

public class User {

    privateintage;

    privateString name;

     

    publicUser() {

         

    }

    publicUser(intage, String name) {

        this.age = age;

        this.name = name;

    }

    publicintgetAge() {

        returnage;

    }

    publicvoidsetAge(intage) {

        this.age = age;

    }

    publicString getName() {

        returnname;

    }

    publicvoidsetName(String name) {

        this.name = name;

    }

    @Override

    publicString toString() {

        return"User [age="+ age +", name="+ name +"]";

    }

     

 

}

2. [代码][Java]代码    

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package com.mango.compare;

 

import java.util.ArrayList;

import java.util.Collections;

import java.util.Comparator;

import java.util.List;

 

public class UserComparator implementsComparator<User> {

 

    public intcompare(User u1, User u2) {

        if(u1.equals(u2)){

            return0;

        }elseif(u1.getAge() < u2.getAge()){

            return1;

        }elseif(u1.getAge() == u2.getAge()){

            intf = u1.getName().compareTo(u2.getName());

            if(f <0){

                return-1;

            }

            return0;

        }else{

            return-1;

        }

    }

     

    publicstaticvoidmain(String[] args) {

        List<User> users =newArrayList<User>();

        users.add(newUser(10,"a"));

        users.add(newUser(11,"d"));

        users.add(newUser(15,"s"));

        users.add(newUser(6,"x"));

        users.add(newUser(17,"a"));

        users.add(newUser(17,"b"));

        users.add(newUser(17,"c"));

        users.add(newUser(17,"d"));

        UserComparator comparator =newUserComparator();

        Collections.sort(users, comparator);

         

        for(User u : users){

            System.out.println(u);

        }

    }

}