循环遍历Map的几种方式

Map<String,String> map=new HashMap<String,String>();map.put("username", "qq");map.put("passWord", "123");map.put("userID", "1");map.put("email", "qq@qq.com"); 第一种用for循环 for(Map.Entry<String, String> entry:map.entrySet()){ System.out.println(entry.getKey()+"--->"+entry.getValue());} 第二种用迭代 Set set = map.entrySet(); Iterator i = set.iterator(); while(i.hasNext()){ Map.Entry<String, String> entry1=(Map.Entry<String, String>)i.next(); System.out.println(entry1.getKey()+"=="+entry1.getValue());} 用keySet()迭代 Iterator it=map.keySet().iterator();while(it.hasNext()){ String key; String value; key=it.next().toString(); value=map.get(key); System.out.println(key+"--"+value);} 用entrySet()迭代 Iterator it=map.entrySet().iterator(); System.out.println( map.entrySet().size());String key; String value;while(it.hasNext()){ Map.Entry entry = (Map.Entry)it.next(); key=entry.getKey().toString(); value=entry.getValue().toString(); System.out.println(key+"===="+value); }