在ArrayList中对ArrayList进行排序

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

public class Main {
    public static void main(String[] args) {
        ArrayList<Integer> numbers = new ArrayList<>();
        numbers.add(5);
        numbers.add(2);
        numbers.add(8);
        numbers.add(1);
        numbers.add(3);

        System.out.println("排序前：" + numbers);

        Collections.sort(numbers);

        System.out.println("排序后：" + numbers);
    }
}

排序前：[5, 2, 8, 1, 3]
排序后：[1, 2, 3, 5, 8]

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

public class Person implements Comparable<Person> {
    private String name;
    private int age;

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

    public String getName() {
        return name;
    }

    public int getAge() {
        return age;
    }

    @Override
    public int compareTo(Person other) {
        // 按照年龄进行升序排序
        return Integer.compare(this.age, other.age);
    }

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

    public static void main(String[] args) {
        ArrayList<Person> people = new ArrayList<>();
        people.add(new Person("Alice", 25));
        people.add(new Person("Bob", 20));
        people.add(new Person("Charlie", 30));

        System.out.println("排序前：" + people);

        Collections.sort(people);

        System.out.println("排序后：" + people);
    }
}

排序前：[Person{name='Alice', age=25}, Person{name='Bob', age=20}, Person{name='Charlie', age=30}]
排序后：[Person{name='Bob', age=20}, Person{name='Alice', age=25}, Person{name='Charlie', age=30}]