ArrayList中对象排序

经常会遇到这样的问题 我们将一组对象存放进List中去，然后我们希望，存放在List当中的对象是根据对象中的某一个属性进行排序的。例如，很经典的例子，ArrayList存放了Person对象，person有很多属性，name，age，gender等等。

这时我们希望存放在ArrayList当中的Person按照年龄排序。方法如下：

先声明一个Person 类

package arraysort;

public class Person {
	private String name = "";
	private String gender="";
	private int age = 0;
	
	public Person(String name,int age){
		this.name = name;
		this.age = age;
	}
	
	public String getName() {
		return name;
	}
	
	public void setName(String name) {
		this.name = name;
	}
	
	public String getGender() {
		return gender;
	}
	
	public void setGender(String gender) {
		this.gender = gender;
	}
	
	public int getAge() {
		return age;
	}
	
	public void setAge(int age) {
		this.age = age;
	}
	
}

 

然后我们实现自己的比较规则，MyComparator

package arraysort;

import java.util.Comparator;


public class MyComparator implements Comparator {

	@Override
	public int compare(Object o1, Object o2) {
		Person person1 = (Person)o1;
		Person person2 = (Person)o2;
		if(person1.getAge() < person2.getAge()){//通过这里设定排列顺序
			return 1;
		}else{
			return 0;
		}
	}
}

 最后测试一下 我们的比较规则 是否可以如所愿

package arraysort;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

public class ArrayListSort {

	public static void main(String args[]){
		List list = new ArrayList<Person>();
		list.add(new Person("Crazy2",34));
		list.add(new Person("Crazy1",35));
		list.add(new Person("Crazy3",33));
		list.add(new Person("Crazy5",31));
		list.add(new Person("Crazy4",32));
		
		for(int i=0; i < list.size();i++){
			Person p = (Person)list.get(i);
			System.out.println("Name:" + p.getName() + "Age:" + p.getAge());
		}
		
		System.out.println("The Above is unsorted.");
		
		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("Name:" + p.getName() + "Age:" + p.getAge());
		}
	}
}

 执行结果：

Name:Crazy2Age:34
Name:Crazy1Age:35
Name:Crazy3Age:33
Name:Crazy5Age:31
Name:Crazy4Age:32
The Above is unsorted.
Name:Crazy1Age:35
Name:Crazy2Age:34
Name:Crazy3Age:33
Name:Crazy4Age:32
Name:Crazy5Age:31

 

 

 

参考网络资源。