Java_基础—集合的遍历之迭代器遍历

偏执的太偏执、 2022-06-12 02:40 213阅读 0赞

package com.soar.collection;
    
    import java.util.ArrayList;
    import java.util.Collection;
    import java.util.Iterator;
    
    import com.soar.bean.Student;
    
    @SuppressWarnings({ "rawtypes", "unchecked" })
    public class Demo5_Iterator {
    /*
    *   * A:迭代器概述
        * 集合是用来存储元素,存储的元素需要查看,那么就需要迭代(遍历) 
        * B:案例演示
        * 迭代器的使用
     */
        public static void main(String[] args) {
            //demo1_Iterator();
            Collection c = new ArrayList();
            c.add(new Student("张三",23));        //Object obj = new Student("张三"，23);
            c.add(new Student("李四",24));
            c.add(new Student("王五",25));
            c.add(new Student("赵六",26));
    
            //获取迭代器
            Iterator it = c.iterator();
            while(it.hasNext()){
                //System.out.println(it.next());    //toString方法
                Student s = (Student)it.next();     //向下转型
                System.out.println(s.getName()+"..."+s.getAge());
            }
        }
    
    private static void demo1_Iterator() {
        Collection c = new ArrayList();
        c.add("a");
        c.add("b");
        c.add("c");
        c.add("d");
    
        //对集合中的元素进行迭代（遍历）
        Iterator it = c.iterator();     //获取迭代器
    
    /*      boolean b1 = it.hasNext();      //判断集合中是否有元素，有就返回true
        Object obj1 = it.next();
        System.out.println(b1);     //true
        System.out.println(obj1);   //a
    
        boolean b2 = it.hasNext();      //判断集合中是否有元素，有就返回true
        Object obj2 = it.next();
        System.out.println(b2);     //true
        System.out.println(obj2);   //b     
    */  
        while(it.hasNext()){
            System.out.println(it.next());
        }
    }
    }