List集合对象中按照不同属性大小排序的实例

实例如下：

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());
 }
}

测试一下：

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());
   }
 }
}

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：

/**
* 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;
 }
}

主类中这样写即可：

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());
   }
 }
}

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：

Collections.sort(list,new Comparator<User>(){ 

public int compare(User arg0, User arg1) { 

// 第一次比较专业 

int i = 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 

int j=arg0.getXXX().compareTo(arg1.getXXX()); 

// 如果学制相同则返回按年龄排序 

if(j==0){ 

return arg0.getCCC().compareTo(arg1.getCCC()); 

} 

return j; 

} 

return i; 

} 

});

以下是另外一个例子

package test;

import java.util.ArrayList; 

import java.util.Collections; 

import java.util.Comparator;

public class ArrayListTest { 

public static void main(String[] args) { 

ArrayList<Exmployee> arrayList = new ArrayList<Exmployee>() ; 

arrayList.add(new Exmployee("zengqiang",new Integer(5000))) ; 

arrayList.add(new Exmployee("zengmin",new Integer(4000))) ; 

arrayList.add(new Exmployee("liuxiaojuan",new Integer(4200))) ; 

arrayList.add(new Exmployee("giuming",new Integer(2200))) ; 

Collections.sort(arrayList, new Comparator<Exmployee>(){ 

public int compare(Exmployee arg0, Exmployee arg1) { 

return arg1.getSalary()-arg0.getSalary() ; //按照工资升序 

//return arg0.getSalary()-arg1.getSalary() ; 按照工资降序 

//return arg0.getName().compareTo(arg1.getName()) ; 按照姓名升序 

} 

}); 

for(Exmployee e:arrayList) 

System.out.println(e.getName()+"'s salary is "+e.getSalary()) ; 

}

}

class Exmployee { 

public Exmployee(String name, int salary) { 

this.name = name ; 

this.salary = salary ; 

}

private String name;

public String getName() { 

return name; 

}

public void setName(String name) { 

this.name = name; 

}

public int getSalary() { 

return salary; 

}

public void setSalary(int salary) { 

this.salary = salary; 

}

private int salary; 

}