Java中List的排序方法

方法一：实现Comparable接口

package com.java.test;

public class Person implements Comparable<Person> {

    private String name;
    private Integer age;

    public Person() {
    }

    public Person(String name, Integer age) {
        this.name = name;
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    @Override
    public int compareTo(Person o) {
        return age.compareTo(o.getAge());//正序

　　　　 //return o.getAge().compareTo(age);//倒序

} }

package com.java.test;

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

public class PersonTest {

    public static void main(String[] args) {
        List<Person> list = new ArrayList<Person>();
        list.add(new Person("E", 16));
        list.add(new Person("C", 14));
        list.add(new Person("A", 12));
        list.add(new Person("B", 13));
        list.add(new Person("D", 15));
        for (Person person : list) {
            System.out.println(person.getAge());
        }
        System.out.println("####################");
        Collections.sort(list);
        for (Person person : list) {
            System.out.println(person.getAge());
        }

    }
}

方法二：调用Collections.sort(List<T> list, Comparator<? super T> c),定义Comparator

package com.java.test;

public class Person {

    private String name;
    private Integer age;

    public Person() {
    }

    public Person(String name, Integer age) {
        this.name = name;
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

}

package com.java.test;

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

public class PersonTest {

    public static void main(String[] args) {
        List<Person> list = new ArrayList<Person>();
        list.add(new Person("E", 16));
        list.add(new Person("C", 14));
        list.add(new Person("A", 12));
        list.add(new Person("B", 13));
        list.add(new Person("D", 15));
        for (Person person : list) {
            System.out.println(person.getAge());
        }
        System.out.println("####################");
        Collections.sort(list, new Comparator<Person>() {
            @Override
            public int compare(Person o1, Person o2) {
                return o1.getAge().compareTo(o2.getAge());//正序
　　　　　　　　　//return o2.getAge().compareTo(o1.getAge());//倒序 
            }
        });
        for (Person person : list) {
            System.out.println(person.getAge());
        }
    }
}