java中遍历MAP的几种方法

清理浏览器书签，把前三个月所有曾经参考过有价值的信息记录在此~

Java代码

Map<String,String> map=new HashMap<String,String>();   2. map.put("username", "qq");   3. map.put("passWord", "123");   4. map.put("userID", "1");   5. map.put("email", "qq@qq.com");  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
Java代码

for(Map.Entry<String, String> entry:map.entrySet()){   2.      System.out.println(entry.getKey()+"—>"+entry.getValue());   3. }  for(Map.Entry<String, String> entry:map.entrySet()){ System.out.println(entry.getKey()+"—>"+entry.getValue()); }

第二种用迭代
Java代码

Set set = map.entrySet();        2. Iterator i = set.iterator();        3. while(i.hasNext()){     4.      Map.Entry<String, String> entry1=(Map.Entry<String, String>)i.next();   5.      System.out.println(entry1.getKey()+"=="+entry1.getValue());   6. }  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
Java代码

Iterator it=map.keySet().iterator();   2. while(it.hasNext()){   3.      String key;   4.      String value;   5.      key=it.next().toString();   6.      value=map.get(key);   7.      System.out.println(key+"–"+value);   8. }  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
Java代码

Iterator it=map.entrySet().iterator();          2. System.out.println( map.entrySet().size());   3. String key;          4. String value;   5. while(it.hasNext()){   6.         Map.Entry entry = (Map.Entry)it.next();          7.         key=entry.getKey().toString();          8.         value=entry.getValue().toString();          9.         System.out.println(key+"===="+value);                    10. }