List的实现类

news2024/11/25 22:30:26

1.ArrayList（数组）

（1）代码

新建学生类：

package com.collection;

public class Student {
    private String name;
    private int age;

    //添加构造方法 都是使用alt+enter快捷键
    public Student() {
        this.name = name;
        this.age = age;
    }

    //添加get set方法
    public String getName() {
        return name;
    }

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

    public int getAge() {
        return age;
    }

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

    //重写toString方法
    @Override
    public String toString() {
        return "Student [name=" + name + ", age=" + age + "]";
    }
}

ArrayList的使用：

package com.collection;

import java.util.ArrayList;
import java.util.Iterator;

/**
 * ArrayList的使用
 * 存储结构是数组，查找遍历速度快，增删慢
 */
public class Demo04 {
    public static void main(String[] args) {
        //创建集合
        ArrayList arrayList = new ArrayList<>();

        //创建对象
        Student s1 = new Student();
        s1.setName("John");
        s1.setAge(23);
        Student s2 = new Student();
        s2.setName("Jane");
        s2.setAge(22);
        Student s3 = new Student();
        s3.setName("Jack");
        s3.setAge(21);
        //1添加元素
        arrayList.add(s1);
        arrayList.add(s2);
        arrayList.add(s3);
        System.out.println("元素个数：" + arrayList);

        //2删除元素
//        arrayList.remove(s1);
//        arrayList.remove(1);
        System.out.println(arrayList);

        //3遍历元素
        System.out.println("-----迭代器--------");
        Iterator it = arrayList.iterator();
        while (it.hasNext()) {
            Student student = (Student) it.next();
            System.out.println(student);
        }
        //其他方法见之前的博客

        //4判断
        System.out.println(arrayList.isEmpty());

        //查找
        System.out.println(arrayList.indexOf(s2));

    }
}

结果：