实例如下：
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package com.huad.luck;
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) {
Person p = new Person();
p.setName("tom");
p.setAge(11);
Person p1 = new Person();
p1.setName("lilei");
p1.setAge(19);
Person p2 = new Person();
p2.setName("json");
p2.setAge(15);
List<Person> list =new ArrayList<Person>();
list.add(p);
list.add(p1);
list.add(p2);
Collections.sort(list,new Comparator<Person>() {
//这里可以再Person中实现 Comparator<T>接口，重写compare方法
@Override
public int compare(Person o1, Person o2) {
//这里按照名字排序
return o1.getName().compareTo(o2.getName());
//这里按照age排序
//return (o1.getAge()+"").compareTo(o2.getAge()+"");
//。。。根据不同属性值排序
}
});
for (int i = 0; i < list.size(); i++) {
System.out.println(list.get(i).getName());
}
}
}
//Person类
package com.huad.luck;
public class Person{
private String name ;
private int age;
public Person(String name , int age) {
this.name = name;
this.age = age;
}
public Person( ) {
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
}
<p style="padding-top: 0px; padding-bottom: 0px; margin-top: 8px; margin-bottom: 8px; line-height: 22.5px; letter-spacing: 0.5px; font-size: 12.5px; word-wrap: break-word; word-break: break-all; color: rgb(51, 51, 51); font-family: 'Microsoft YaHei', Verdana, sans-serif, 宋体;"><span style="padding: 0px; margin: 0px; letter-spacing: normal; font-stretch: normal; font-size: 14px; line-height: 24px; font-family: Tahoma; color: rgb(0, 0, 0);">用collection.sort（）方法对list集合排序</span><br style="padding: 0px; margin: 0px;" /></p><p style="padding-top: 0px; padding-bottom: 0px; margin-top: 0px; margin-bottom: 0px; line-height: 24px; font-size: 14px; word-wrap: break-word; word-break: break-all; font-stretch: normal; font-family: Tahoma;"><span style="padding: 0px; margin: 0px; list-style: none outside none; word-wrap: break-word; word-break: normal;"><span style="padding: 0px; margin: 0px; list-style: none outside none; line-height: 21px; word-wrap: break-word; word-break: normal;"></span></span></p><p style="padding-top: 0px; padding-bottom: 0px; margin-top: 1em; margin-bottom: 0.5em; line-height: 24px; font-size: 14px; word-wrap: break-word; word-break: break-all; font-stretch: normal; font-family: Tahoma;">第一种是list中的对象实现Comparable接口，如下：<span style="padding: 0px; margin: 0px; list-style: none outside none; word-wrap: break-word; word-break: normal;"> </span></p><pre class="java" style="padding: 5px; margin-top: 0px; margin-bottom: 0px; line-height: 18px; font-size: 9pt; font-family: 'Courier New', Arial; border: 1px solid rgb(221, 221, 221); color: rgb(51, 51, 51); background: rgb(246, 246, 246);">/**
* 根据order对User排序
*/
public class User implements Comparable<User>{
private String name;
private Integer order;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getOrder() {
return order;
}
public void setOrder(Integer order) {
this.order = order;
}
public int compareTo(User arg0) {
return this.getOrder().compareTo(arg0.getOrder());
}
}
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测试一下：
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public class Test{
public static void main(String[] args) {
User user1 = new User();
user1.setName("a");
user1.setOrder(1);
User user2 = new User();
user2.setName("b");
user2.setOrder(2);
List<User> list = new ArrayList<User>();
//此处add user2再add user1
list.add(user2);
list.add(user1);
Collections.sort(list);
for(User u : list){
System.out.println(u.getName());
}
}
}
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输出结果如下
a
b
第二种方法是根据Collections.sort重载方法来实现，例如：
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/**
* 根据order对User排序
*/
public class User { //此处无需实现Comparable接口
private String name;
private Integer order;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getOrder() {
return order;
}
public void setOrder(Integer order) {
this.order = order;
}
}
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主类中这样写即可：
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public class Test{
public static void main(String[] args) {
User user1 = new User();
user1.setName("a");
user1.setOrder(1);
User user2 = new User();
user2.setName("b");
user2.setOrder(2);
List<User> list = new ArrayList<User>();
list.add(user2);
list.add(user1);
Collections.sort(list,new Comparator<User>(){
public int compare(User arg0, User arg1) {
return arg0.getOrder().compareTo(arg1.getOrder());
}
});
for(User u : list){
System.out.println(u.getName());
}
}
}
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输出结果如下
a
b
前者代码结构简单，但是只能根据固定的属性排序，后者灵活，可以临时指定排序项，但是代码不够简洁
多字段的场合：
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Collections.sort(list,newComparator<User>(){
publicintcompare(Userarg0,Userarg1){
//第一次比较专业
inti=arg0.getOrder().compareTo(arg1.getOrder());
//如果专业相同则进行第二次比较
if(i==0){
//第二次比较
intj=arg0.getXXX().compareTo(arg1.getXXX());
//如果学制相同则返回按年龄排序
if(j==0){
returnarg0.getCCC().compareTo(arg1.getCCC());
}
returnj;
}
returni;
}
});
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以下是另外一个例子
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packagetest;
importjava.util.ArrayList;
importjava.util.Collections;
importjava.util.Comparator;
publicclassArrayListTest{
publicstaticvoidmain(String[]args){
ArrayList<Exmployee>arrayList=newArrayList<Exmployee>();
arrayList.add(newExmployee("zengqiang",newInteger(5000)));
arrayList.add(newExmployee("zengmin",newInteger(4000)));
arrayList.add(newExmployee("liuxiaojuan",newInteger(4200)));
arrayList.add(newExmployee("giuming",newInteger(2200)));
Collections.sort(arrayList,newComparator<Exmployee>(){
publicintcompare(Exmployeearg0,Exmployeearg1){
returnarg1.getSalary()-arg0.getSalary();//按照工资升序
//returnarg0.getSalary()-arg1.getSalary();按照工资降序
//returnarg0.getName().compareTo(arg1.getName());按照姓名升序
}
});
for(Exmployeee:arrayList)
System.out.println(e.getName()+"'ssalaryis"+e.getSalary());
}
}
classExmployee{
publicExmployee(Stringname,intsalary){
this.name=name;
this.salary=salary;
}
privateStringname;
publicStringgetName(){
returnname;
}
publicvoidsetName(Stringname){
this.name=name;
}
publicintgetSalary(){
returnsalary;
}
publicvoidsetSalary(intsalary){
this.salary=salary;
}
privateintsalary;
}
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