public static void main(String[] args) {
		Map<String,String> map = new HashMap<String,String>();
		map.put("a", "1");
		map.put("b", "2");
		map.put("c", "3");
		map.put("d", "4");
		map.put("e", "5");
		
		//同时遍历key跟value值,推荐使用
		for (Map.Entry<String,String> entry : map.entrySet()) {
			System.out.println(entry.getKey()+";"+entry.getValue());
		}
		
		//只遍历key值
		for (String key : map.keySet()) {
			System.out.println(key);
		}
		
		//只遍历value值
		for (String value : map.values()) {
			System.out.println(value);
		}
		
		//通过遍历key值获取value值,效率最低,不推荐使用
		for (String key : map.keySet()) {
			String value = map.get(key);
			System.out.println(key+";"+value);
		}
		
		//java8 lambda表达式
		List<String> list = new ArrayList<String>(map.size());
		map.forEach((key,value) -> {list.add(value);});
		System.out.println(list);
	}