java教程之二个arraylist排序的示例分享_Java教程-查字典教程网
java教程之二个arraylist排序的示例分享
java教程之二个arraylist排序的示例分享
发布时间:2016-12-28 来源:查字典编辑
摘要:示例1复制代码代码如下:packagecom.yonyou.test;importjava.util.ArrayList;importjav...

示例1

复制代码 代码如下:

package com.yonyou.test;

import java.util.ArrayList;

import java.util.Collections;

import java.util.Comparator;

import java.util.List;

public class Test {

public static void main(String[] args) {

Student zlj = new Student("丁晓宇", 21);

Student dxy = new Student("赵四", 22);

Student cjc = new Student("张三", 11);

Student lgc = new Student("刘武", 19);

List<Student> studentList = new ArrayList<Student>();

studentList.add(zlj);

studentList.add(dxy);

studentList.add(cjc);

studentList.add(lgc);

System.out.println("按照年齡排序:");

Collections.sort(studentList, new SortByAge());

for (Student student : studentList) {

System.out.println(student.getName() + " / " + student.getAge());

}

System.out.println(" ========= ");

System.out.println("按照姓名排序");

Collections.sort(studentList, new SortByName());

for (Student student : studentList) {

System.out.println(student.getName() + " / " + student.getAge());

}

}

}

class SortByAge implements Comparator {

public int compare(Object o1, Object o2) {

Student s1 = (Student) o1;

Student s2 = (Student) o2;

if (s1.getAge() > s2.getAge())

return 1;

else if (s1.getAge() == s2.getAge()) {

return 0;

}

return -1;

}

}

class SortByName implements Comparator {

public int compare(Object o1, Object o2) {

Student s1 = (Student) o1;

Student s2 = (Student) o2;

if(s1.getName().compareTo(s2.getName()) < 0)

return -1;

else if (s1.getName().compareTo(s2.getName()) > 0) {

return 1;

}

return 0;

}

}

class Student{

private int age;

private String name;

public int getAge() {

return age;

}

public void setAge(int age) {

this.age = age;

}

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

public Student(String name,int age) {

this.age = age;

this.name = name;

}

}

示例2

常常遇到数组排序的问题.比如我有一个Person类,它的实例对象存储在ArrayList数组中,现在要把ArrayList数组中 的Person对象按照年龄排序.

其实这种情况经常遇到.

下面给出源代码:

1:Person.java文 件:

复制代码 代码如下:

public class Person{

String name;

int age;

public Person(String name,int age){

this.name = name;

this.age = age;

}

public int getAge() {

return age;

}

public void setAge(int age) {

this.age = age;

}

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

}

2:Mycomparator.java

复制代码 代码如下:

// 实现Comparator接口,也就是定义排序规则,你几乎可以定义任何规则

package com.infoearth;

import java.util.*;

public class Mycomparator implements Comparator{

public int compare(Object o1,Object o2) {

Person p1=(Person)o1;

Person p2=(Person)o2;

if(p1.age<p2.age)

return 1;

else

return 0;

}

}

3:ListSort.java

复制代码 代码如下:

package com.infoearth;

import java.util.ArrayList;

import java.util.Collections;

import java.util.Comparator;

public class ListSort {

public static void main(String[] args){

ArrayList list = new ArrayList();

list.add(new Person("lcl",28));

list.add(new Person("fx",23));

list.add(new Person("wqx",29));

Comparator comp = new Mycomparator();

Collections.sort(list,comp);

for(int i = 0;i<list.size();i++){

Person p = (Person)list.get(i);

System.out.println(p.getName());

}

}

}

当然,如果你的List包装的是基本类型或者String,则只要 Collections.sort(list);即可

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