Java如何遍历Map的所有的元素

JDK1.4中

<font color="#0000ff">Map map = new HashMap();  
   
    Iterator it = map.entrySet().iterator();  
  
      while (it.hasNext()) {  
   
         Map.Entry entry = (Map.Entry) it.next();  
 
         Object key = entry.getKey();  

         Object value = entry.getValue();  
 
}</font>  

JDK1.5中,应用新特性For-Each循环

 Map m = new HashMap();  
 
 for(Object o : map.keySet()){  
  
    map.get(o);  

 }  

返回的 set 中的每个元素都是一个 Map.Entry 类型。
   1. <font color="#0000ff">private Hashtable<String, String> emails = new Hashtable<String, String>();</font> 

另外 我们可以先把hashMap 转为集合Collection，再迭代输出，不过得到的对象

# <font color="#0000ff">//方法一: 用entrySet()  
#   
#    Iterator it = emails.entrySet().iterator();  
#   
#    while(it.hasNext()){  
#   
#     Map.Entry m=(Map.Entry)it.next();  
#   
#     logger.info("email-" + m.getKey() + ":" + m.getValue());  
#   
#    }  
#   
#     
#   
#    // 方法二：jdk1.5支持，用entrySet()和For-Each循环()  
#   
#    for (Map.Entry<String, String> m : emails.entrySet()) {  
#   
#      
#   
#     logger.info("email-" + m.getKey() + ":" + m.getValue());  
#   
#    }  
#   
#     
#   
#    // 方法三：用keySet()  
#   
#    Iterator it = emails.keySet().iterator();  
#   
#    while (it.hasNext()){  
#   
#     String key;  
#   
#     key=(String)it.next();  
#   
#     logger.info("email-" + key + ":" + emails.get(key));  
#   
#    }  
#   
#   
#   
# // 方法五：jdk1.5支持，用keySEt()和For-Each循环  
#   
#   
#   
# for(Object m: emails.keySet()){  
#   
#     logger.info("email-" + m+ ":" + emails.get(m));  
#   
#    }  
# </font>