1、最常用的方式,加强for循环遍历键值

        Map<String,String> map2 = new HashMap<String,String>();
        map2.put("name1","王大");
        map2.put("name2","王二");
        map2.put("name3","王三");
        map2.put("name4","王四");
        //在键值都需要时使用
        for (Map.Entry<String,String> entry : map2.entrySet()){
            System.out.println(entry.getKey() +"==>"+ entry.getValue());
        }

2、for-each循环中遍历keys或values

        for (String keyName : map2.keySet()){
            System.out.println(keyName);
        }
        for (String valueName : map2.values()){
            System.out.println(valueName);
        }

3、通过键找值遍历

      for (String key4 : map2.keySet()){
            String value4 = map2.get(key4);
            System.out.println(key4 +"==>"+ value4);
        }

4、使用Iterator遍历

       Map map = new HashMap();
       map.put("name1","王大");
       map.put("name2","王二");
       map.put("name3","王三");
       map.put("name4","王四");
       //不使用泛型
       Iterator iterator = map.keySet().iterator();
       Object key,value;
       while (iterator.hasNext()){
           key = iterator.next();
           value = map.get(key);
           System.out.println(key + "==>" + value);
       }
        //使用泛型
        Iterator<Map.Entry<String,String>> iterator2 = map2.entrySet().iterator();
        while (iterator2.hasNext()){
            Map.Entry<String,String> entry = iterator2.next();
            System.out.println(entry.getKey() + "==>" + entry.getValue());
        }

5、使用java8新特性forEach+Lambda遍历

 map2.forEach((k,v)-> System.out.println(k+"的值为"+v));

参考文章：https://www.cnblogs.com/fqfanqi/p/6187085.html