代码呈现

import java.util.ArrayList;

public class ArrayListTest {
    public static void main(String[] args) {
        //创建集合
        ArrayList<String> list = new ArrayList();

        //添加元素
        list.add("A");
        list.add("B");
        list.add("C");
        list.add("D");

        //遍历集合
        System.out.print("[");
        for (int i = 0; i < list.size(); i++) {
            if (i == list.size() - 1) {
                System.out.print(list.get(i));
            }else {
                System.out.print(list.get(i) + ", ");
            }

        }
        System.out.println("]");
    }
}

代码呈现

import java.util.ArrayList;

public class ArrayListTest2 {
    public static void main(String[] args) {
        //创建一个集合
        ArrayList<Integer> list = new ArrayList();
        list.add(1);
        list.add(2);
        list.add(3);
        list.add(4);
        list.add(5);

        //遍历
        System.out.print("[");
        for (int i = 0; i <list.size() ; i++) {
            if (i == list.size() - 1){
                System.out.print(list.get(i));
            }else {
                System.out.print(list.get(i) + ", ");
            }

        }
        System.out.println("]");

    }
}

代码呈现

student类

public class Student {

        //私有化成员变量
        //空参构造方法
        //待全部参数的构造方法
        //get set方法

        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;
        }
    }

代码

import java.util.ArrayList;

public class ArrayListTest4 {
    public static void main(String[] args) {
        //创建集合
        ArrayList<Student> list = new ArrayList();

        //创建学生对象
        Student s1 = new  Student("zhangsan",23);
        Student s2 = new  Student("lisi",22);
        Student s3 = new  Student("wangwu",21);
        
        //添加元素
        list.add(s1);
        list.add(s2);
        list.add(s3);
        
        //遍历集合
        for (int i = 0; i < list.size(); i++) {
            Student stu = list.get(i);
            System.out.println(stu.getName()+", "+stu.getAge());
        }

    }
}

代码呈现
student类用上一题的类

import java.util.ArrayList;
import java.util.Scanner;

public class ArrayListTest5 {
    public static void main(String[] args) {
        ArrayList<Student> list = new ArrayList();

        //键盘录入并添加到集合
        Scanner sc = new Scanner(System.in);
        for (int i = 0; i <3 ; i++) {
            Student s = 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();

            //把name 和 age 赋值给集合
            s.setName(name);
            s.setAge(age);

            //把学生对象添加到集合
            list.add(s);


        }
        System.out.println(list.size());
    }
}