Java中Collections的sort方法和Comparable与Comparator的比较

一、Comparable

新建Student1类，类实现Comparable接口，并重写compareTo方法

public class Student1 implements Comparable<Student1> {

    private String name;
    private int age;

    public Student1() {
    }

    public Student1(String name, int 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(Student1 s) {
        int num = this.age - s.age;
        int num1 = (num == 0 ? this.name.compareTo(s.name) : num);
        return num1;
    }
}

调用

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

public class Student1Test {
    public static void main(String[] args) {
        List<Student1> list1 = new ArrayList<Student1>();
        list1.add(new Student1("林青霞", 27));
        list1.add(new Student1("风清扬", 30));
        list1.add(new Student1("刘晓曲", 28));
        list1.add(new Student1("武鑫", 29));
        list1.add(new Student1("林青霞", 27));

        Collections.sort(list1);
        for (Student1 s : list1) {
            System.out.println(s.getName() + "---" + s.getAge());
        }
    }
}

二、Comparator

新建Student2类

public class Student2 {

    private String name;
    private int age;

    public Student2() {
    }

    public Student2(String name, int 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;
    }
}

调用

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

public class Student2Test {
    public static void main(String[] args) {
        List<Student2> list2 = new ArrayList<Student2>();
        list2.add(new Student2("林青霞", 27));
        list2.add(new Student2("风清扬", 30));
        list2.add(new Student2("刘晓曲", 28));
        list2.add(new Student2("武鑫", 29));
        list2.add(new Student2("林青霞", 27));

        //方式一
        Collections.sort(list2, new MyComparator());
        for (Student2 s : list2) {
            System.out.println(s.getName() + "---" + s.getAge());
        }

        //逆序
        //方式二：匿名类
        Collections.sort(list2, new Comparator<Student2>() {
            @Override
            public int compare(Student2 s1, Student2 s2) {
                int num = s2.getAge() - s1.getAge();
                int num1 = (num == 0 ? s2.getName().compareTo(s1.getName())
                        : num);
                return num1;
            }
        });
        for (Student2 s : list2) {
            System.out.println(s.getName() + "---" + s.getAge());
        }
    }
}

class MyComparator implements Comparator<Student2> {
    @Override
    public int compare(Student2 s1, Student2 s2) {
        int num = s1.getAge() - s2.getAge();
        int num1 = (num == 0 ? s1.getName().compareTo(s2.getName()) : num);
        return num1;
    }
}