集合应用

package Lianxi1219;public class Student1 {    public String name;    public int age;    public Student1() {    }    public Student1(String name,int age){        this.name=name;        this.age=age;    }    @Override    public String toString() {        return "Student1 [name=" + name + ", age=" + age + "]";    }}

package Lianxi1219;import java.util.ArrayList;import java.util.Arrays;import java.util.Iterator;import java.util.List;public class Stest1 {    @SuppressWarnings("rawtypes")    List list=new ArrayList();//在main函数之前作为全局类型定义结合    public static void main(String[] args) {        Stest1 s=new Stest1();//实例化自身类        s.add();    }    @SuppressWarnings("unchecked")    public void add(){        list.add(new Student1("张三",23));        list.add(new Student1("李四",23));        System.out.println(list.size());        @SuppressWarnings("rawtypes")        List list2=new ArrayList();        list2.add(new Student1("wang",23));        list2.add(new Student1("tom",23));        list2.add(new Student1("lily",23));        list.addAll(1,list2);//把list2中元素从下标为1的位置添加进去        Student1[] Arrstu={new Student1("zhao",34),new Student1("qian",34),new Student1("sun",34)};        Arrays.asList(Arrstu);//把存有对象的数组作为一个集合输出        list.addAll(2,Arrays.asList(Arrstu));        //查询方法1        for (int i = 0; i < list.size(); i++) {            Student1 stu=(Student1)list.get(i);//遍历集合把下标从0开始的集合元素从object类型强转为Student1类型            System.out.println(stu.name);//只打印集合中元素的某一项属性        }        //查询方法2        for (Object obj : list) {            if(obj instanceof Student1){                Student1 s = (Student1) obj;                System.out.println(s.name);            }        }         //查询方法3使用迭代器Iterator(也是一个集合)        Iterator it=list.iterator();        while(it.hasNext()){//后边有元素是为true            Object obj=it.next();            if(obj instanceof Student1){                Student1 stu=(Student1) obj;                System.out.println(stu.name);            }        }    }}