public class Demo {
	public static void main(String[] args) {
		Set set = new HashSet();//定义set集合
		set.add("haha");//向set中添加数据
		set.add("hehe");
		set.add("hello");
		//set遍历方法1
		for (Object object : set) {
			System.out.println(object);
		}
		System.out.println("----------");
		//set遍历方法2;Iterator(迭代器)
		for (Iterator iterator=set.iterator();iterator.hasNext();) {
			String str=(String)iterator.next();
			System.out.println(str);
		}
		System.out.println("-------");
		Map map = new HashMap();//定义map集合
		map.put("1", "haha");//map集合中添加元素
		map.put("2", "hehe");
		map.put("3", "hello");
		//map遍历方法1
		Set set1 = map.keySet();//将map中的key定义成set集合
		for (Iterator iterator = set1.iterator(); iterator.hasNext();) {
			String key = (String) iterator.next();
			String value = (String) map.get(key);
			System.out.println(key + ":" + value);
		}
		System.out.println("--------");
		//map遍历方法2
		Set set2 = map.entrySet();//将map中的entry对象(键值对)定义成一个set集合
		for (Iterator iterator = set2.iterator(); iterator.hasNext();) {
			Map.Entry entry = (Entry) iterator.next();
			String key = (String) entry.getKey();
			String value = (String) entry.getValue();
			System.out.println(key + ":" + value);
		}
}
}
原文:https://www.cnblogs.com/sunda847882651/p/9513705.html