map遍历的几种方式

java代码：

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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");

方法一、for循环

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for(Map.Entry<String, String> entry:map.entrySet()){          System.out.println(entry.getKey()+"--->"+entry.getValue());      }

方法二、迭代

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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());      }

方法三、keySet()迭代

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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);     }

方法四、entrySet()迭代

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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);                           }  　　  for (Map.Entry<String, String> entry : map.entrySet()) {         　　System.out.println("key= " + entry.getKey() + " and value= " + entry.getValue());   　　 }