package ArrayListDemo;

public class Student {
    //1.私有化成员变量
    private String name;
    private int age;

    public Student() {
    }

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

    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;
    }

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

package ArrayListDemo;

import java.util.ArrayList;

public class ArrayList4 {
    public static void main(String[] args) {
        //1.创建集合
        ArrayList<Student> list = new ArrayList<Student>();
        //2.创建学生对象
        Student s1 = new Student("zhangsan",18);
        Student s2 = new Student("lisi",19);
        Student s3 = new Student("wangwu",20);
        //3.添加元素
        list.add(s1);
        list.add(s2);
        list.add(s3);
        //4.遍历集合
        for (int i = 0; i < list.size(); i++) {
            //i 索引 list.get(i) 元素/学生信息
            Student stu = list.get(i);
            System.out.println(stu.getName()+","+stu.getAge());

        }

    }
}

增加功能，可以进行手动输入数据

package ArrayListDemo;

import javax.naming.Name;
import java.util.ArrayList;
import java.util.Scanner;

public class ArrayListDemo5 {
    public static void main(String[] args) {
        //1.创建集合
        ArrayList<Student> list = new ArrayList<Student>();
        //2.键盘录入学生信息并添加到集合当中
        Scanner sc =new Scanner(System.in);
        for (int i = 0; i < 3 ; i++) {
            Student st = new Student();
            System.out.println("请输入学生姓名");
            String name = sc.next();
            System.out.println("请输入学生年龄");
            int age = sc.nextInt();

            //3.把name和age赋值给学生
            st.setName(name);
            st.setAge(age);
            list.add(st);
        }
        for (int i = 0; i < list.size(); i++) {
            //i 索引 list.get(i) 元素/学生信息
            Student stu = list.get(i);
            System.out.println(stu.getName()+","+stu.getAge());

        }
    }
}

package ArrayListDemo;

import java.util.ArrayList;

public class ArrayListDemo6 {
    public static void main(String[] args) {
        //1.创建集合
        ArrayList<User> list = new ArrayList<User>();
        //2.创建三个对象
        User u1 = new User("jinrong001", "zhangsan", "zs2002");
        User u2 = new User("jinrong002", "lisi", "ls2002");
        User u3 = new User("jinrong003", "wangwu", "ww2003");
        //3.把用户对象加入到集合当中
        list.add(u1);
        list.add(u2);
        list.add(u3);
        //4.调用方法，查看id是否存在
        boolean flag = contains(list, "jinrong001");
        System.out.println(flag);

    }
    //1.我要干嘛 根据id查找用户
    //2.我干这件事情需要什么才能完成 在list找id
    //3.调用处是否需要使用方法的结果 返回
    public static boolean contains(ArrayList<User> list , String id){
        for (int i = 0; i < list.size(); i++) {
            boolean uid = list.get(i).getId().equals(id);
            if(uid){
                //如果找到了返回true
                return true;
            }
        }
        //当循环结束还是没有一样的返回false;
        return false;
    }

}