java循环遍历map

JDK1.4中
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();
}
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。
private Hashtable<String, String> emails = new Hashtable<String, String>();
  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
//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));
}
      Map    aa    =    new    HashMap();     
    aa.put("tmp1",    new    Object());      //追加      替换用同样的函数.     
    aa.remove("temp1");                        //删除      f
    or    (Iterator    i    = &n