集合框架之HashMap三种遍历获取元素的方式

第一种：entrySet()

HashMap<String, String> map = new HashMap<String , String>();
    map.put("name", "value");
    
    Iterator<Entry<String,String>> it = map.entrySet().iterator();
    	while (it.hasNext()) {
			Map.Entry<String, String> entry = (Map.Entry<String, String>) it.next();
			String key = entry.getKey();
			String value = entry.getValue();
			System.out.println(key+":"+value);
		
    }

第二种：通过key值

Iterator<String> it1 = map.keySet().iterator();
    	while (it1.hasNext()) {
			String  key= (String) it1.next();
			String value = map.get(key);
			System.out.println(key+":"+value);
		}

第三种：通过value值

 Iterator<String> it2 = map.values().iterator();
	    while (it2.hasNext()) {
			String va = (String) it2.next();
			System.out.println(va);
		}

显而易见：第二种最便捷