lambda表達式之list排序

lambda表達式常用的list排序

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

import static java.util.Comparator.comparing;

public class LambdaTest {
    public static void main(String[] args) {

        List<Person> personList = new ArrayList<>();
        personList.addAll(Arrays.asList(
                new Person(12, 178, "張三2"),
                new Person(12, 176, "李四"),
                new Person(16, 180, "王五"))
        );
        System.out.println(personList);

        //普通排序
        personList.sort(new Comparator<Person>() {
            public int compare(Person a1, Person a2) {
                return a1.getAge().compareTo(a2.getAge());
            }
        });
        //lambda排序1
        personList.sort((Person a1, Person a2) -> a1.getAge().compareTo(a2.getAge()));
        //lambda排序2
        personList.sort((a1, a2) -> a1.getAge().compareTo(a2.getAge()));
        //lambda排序3
        personList.sort(comparing(Person::getAge)); //正序排序
        personList.sort(comparing(Person::getAge).reversed()); //倒序排序
        //如果年齡一樣，按照身高排序1
        personList.sort((a1, a2) -> {
            if (a1.getAge() == a2.getAge()) {
                return a1.getHeight() - a2.getHeight();
            }else{
                return a1.getAge() - a2.getAge();
            }
        });
        //如果年齡一樣，按照身高排序2
        personList.sort(comparing(Person::getAge).thenComparing(Person::getHeight));

        System.out.println(personList);

    }
}

 

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

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

    public Integer getAge() {
        return age;
    }

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

    public Integer getHeight() {
        return height;
    }

    public void setHeight(Integer height) {
        this.height = height;
    }

    public String getName() {
        return name;
    }

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

    @Override
    public String toString() {
        return "Person{" +
                "age=" + age +
                ", height=" + height +
                ", name='" + name + '\'' +
                '}';
    }
}