创建学生类 有姓名 学校 和年龄 覆盖toString() 1放到集合ArrayList 然后 2在第2个位置插入1个学生信息 3判断 刘德华这个学生是否存在 存在就打出来, 4输出全部学生信息 直接打印对象

学生类

 package com.lanxi.demo1;
 public class Student {
     //创建属性  姓名，学校，年龄
     private String name;
     private String school;
     private int age;
     public Student(String name, String school, int age) {    //创建有参构造方法
         super();
         this.name = name;
         this.school = school;
         this.age = age;
     }
     //构造无参构造方法
     public Student() {
         super();
     }
     //重写toString方法
     @Override
     public String toString() {
         return "Student [name=" + name + ", school=" + school + ", age=" + age
                 + "]";
     }
     //创建get,set方法
     public String getName() {
         return name;
     }
     public void setName(String name) {
         this.name = name;
     }
     public String getSchool() {
         return school;
     }
     public void setSchool(String school) {
         this.school = school;
     }
     public int getAge() {
         return age;
     }
     public void setAge(int age) {
         this.age = age;
     }

 }

测试类

 package com.lanxi.demo1;

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

 public class Test {

     public static void main(String[] args) {
         List list=new ArrayList();
         list.add(new Student("张三","师大",18));
         list.add(new Student("李四","理工",20));
         list.add(new Student("王五","旅游",25));
         list.add(1, new Student("刘德华","旅游",35));
         //for循环遍历
         /*for (int i = 0; i < list.size(); i++) {
             System.out.println(list.get(i));
         }*/
         //迭代便利
         Iterator it=list.iterator();
         while(it.hasNext()){
             Student stu=(Student)it.next();//强转
             //输出新建对象的全部信息（姓名，学校，年龄）
             System.out.println(stu);
             //判断“刘德华”是否存在
             if ("刘德华".equals(stu.getName())) {
                 //找到对象
                 System.out.println("it is exist");
             }else{
                 //找不到对象
                 System.out.println("no find");
             }
         }
     }
 }

运行结果