collection集合迭代

package com.lichennan.collection;

import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.Iterator;

//关于集合的迭代/遍历
public class CollectionTest03 {
    public static void main(String[] args) {
        //创建集合对象
        Collection c1  = new ArrayList();  //ArrayList集合：有序可重复
        //添加元素
        c1.add(1);
        c1.add(2);
        c1.add(3);
        c1.add(4);
        c1.add(2);

        //迭代集合
        Iterator it = c1.iterator();
        while (it.hasNext()){
            Object obj = it.next();
            System.out.println(obj);
        }
        System.out.println("===============");
        //HashSet集合：无序不可重复
        Collection c2 = new HashSet();
        c2.add(500);
        c2.add(200);
        c2.add(300);
        c2.add(300);
        c2.add(200);
        Iterator it2 = c2.iterator();
        while (it2.hasNext()){
            System.out.println(it2.next());
        }
    }
}