关于遍历问题

for(String str : List){
//for(int i;i<List;i++){
}

Iterator<String> ite = list.iterator
while(ite.hasNext()){//判断下一个之后有没有元素

}

//通过Map.keySet遍历key和value
      for (String key : map.keySet()) {
       System.out.println("key= "+ key + " and value= " + map.get(key));
      }    

//通过Map.entrySet使用iterator遍历key和value
      Iterator<Map.Entry<String, String>> it = map.entrySet().iterator();
      while (it.hasNext()) {
       Map.Entry<String, String> entry = it.next();
       System.out.println("key= " + entry.getKey() + " and value= " + entry.getValue());
      }

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

//通过Map.values()遍历所有的value，但不能遍历key
      for (String v : map.values()) {
       System.out.println("value= " + v);
      }