用 lambda 表达式 对 List 进行排序

        List<Integer> list = new ArrayList<>();
        list.add(4);
        list.add(6);
        list.add(3);
        list.add(5);
        list.add(1);
        list.add(2);
        Iterator<Integer> iterator = list.iterator();
        System.out.println("排序前：");
        while(iterator.hasNext()) {
            System.out.print(iterator.next()+" ");
        }
        list.sort((a, b) -> a - b);       //排序
        Iterator<Integer> iteratorSort = list.iterator();
        System.out.println("
"+"排序后：");
        while(iteratorSort.hasNext()) {
            System.out.print(iteratorSort.next()+" ");
        }

输出结果：

排序前：
4 6 3 5 1 2 
排序后：
1 2 3 4 5 6 

下面用实体类里面的属性进行排序：

Person类：

public class Person {
    
    private String name;
    
    private Integer age;
    
    private Integer score;
    

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

    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;
    }

    public Integer getScore() {
        return score;
    }

    public void setScore(Integer score) {
        this.score = score;
    }

    @Override
    public String toString() {
        return "Person [name=" + name + ", age=" + age + ", score=" + score + "]";
    }
    

}

测试一下：

        List<Person> list = new ArrayList<>();
        list.add(new Person("lc",22,100));
        list.add(new Person("ly",16,70));
        list.add(new Person("yyz",20,60));
        list.add(new Person("mxy",20,80));
        list.add(new Person("lxy",15,90));
        list.sort((a, b) -> a.getAge() - b.getAge());   //按年龄排序
        System.out.println("按年龄排序:");
        Iterator<Person> iterator_age = list.iterator(); 
        while(iterator_age.hasNext()) {
            System.out.println(iterator_age.next()+" ");
        }
        
        list.sort((a, b) -> a.getScore() - b.getScore());
        System.out.println("按分数排序:");
        Iterator<Person> iterator_score = list.iterator();
        while(iterator_score.hasNext()) {
            System.out.println(iterator_score.next()+" ");
        }

输出结果：

按年龄排序:
Person [name=lxy, age=15, score=90] 
Person [name=ly, age=16, score=70] 
Person [name=yyz, age=20, score=60] 
Person [name=mxy, age=20, score=80] 
Person [name=lc, age=22, score=100] 
按分数排序:
Person [name=yyz, age=20, score=60] 
Person [name=ly, age=16, score=70] 
Person [name=mxy, age=20, score=80] 
Person [name=lxy, age=15, score=90] 
Person [name=lc, age=22, score=100]