常用map总结

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>();    
  
   //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));    
   }    
  
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    
  
   Map    aa    =    new    HashMap();      
   aa.put("tmp1",    new    Object());      //追加      替换用同样的函数.      
   aa.remove("temp1");                        //删除      
   for    (Iterator    i    =    aa.values().iterator();    i.hasNext();    )    {      
           Object    temp    =    i.next();      
   }          //遍历      
  
  
来个完整的，包含TreeSet的元素内部排序的    
  
public static void main(String[] args) {    
   ArrayList<String> list = new ArrayList<String>();    
   HashMap<Object,Object> hash = new HashMap<Object,Object>();    
   TreeMap<Object,Object> treeMap = new TreeMap<Object,Object>();    
   list.add("a");    
   list.add("b");    
   list.add("c");    
  
   hash.put(3, 3);    
   hash.put(4, 4);    
   hash.put(5, 5);    
   hash.put(6, 6);    
   hash.put(1, 1);    
   hash.put(2, 2);    
  
   treeMap.put(1, 1);    
   treeMap.put(2, 2);    
   treeMap.put(3, 3);    
   treeMap.put(4, 4);    
   treeMap.put(5, 5);    
   treeMap.put(6, 6);    
  
   //list遍历    
   for(String m: list){    
    System.out.println(m);    
   }    
   // hashmap entrySet() 遍历    
   for(Map.Entry<Object,Object> m: hash.entrySet()){    
    System.out.println(m.getKey()+"---"+m.getValue());    
   }    
   //hashmap keySet() 遍历    
   for(Object m: hash.keySet()){    
    System.out.println(m+"---"+hash.get(m));    
   }    
   // treemap keySet()遍历    
   for(Object m: treeMap.keySet()){    
    System.out.println(m+"---"+treeMap.get(m));    
   }    
} 
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