java遍歷對(duì)象

2019-11-17 04:00:15

字體：大中小

供稿：網(wǎng)友

JDK1.4中

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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();

}

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,應(yīng)用新特性For-Each循環(huán)

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Map m = new HashMap();

for(Object o : map.keySet()){

 map.get(o);

}

Map m = new HashMap();

for(Object o : map.keySet()){

 map.get(o);

}返回的 set 中的每個(gè)元素都是一個(gè) Map.Entry 類型。

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private Hashtable<String, String> emails = new Hashtable<String, String>();

private Hashtable<String, String> emails = new Hashtable<String, String>(); 另外我們可以先把hashMap 轉(zhuǎn)為集合Collection，再迭代輸出，不過(guò)得到的對(duì)象

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//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循環(huán)()

 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循環(huán)

for(Object m: emails.keySet()){

 logger.info("email-" + m+ ":" + emails.get(m));

 }


//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循環(huán)()

 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循環(huán)

for(Object m: emails.keySet()){

 logger.info("email-" + m+ ":" + emails.get(m));

 }
 Map aa = new HashMap();

aa.put("tmp1", new Object());

 //追加 替換用同樣的函數(shù).

aa.remove("temp1");

//刪除

for (Iterator i = aa.values().iterator(); i.hasNext(); ) {

 Object temp = i.next();

} //遍歷



來(lái)個(gè)完整的，包含TreeSet的元素內(nèi)部排序的

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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遍歷

 for(String m: list){

 System.out.println(m);

 }

 // hashmap entrySet() 遍歷

 for(Map.Entry<Object,Object> m: hash.entrySet()){

 System.out.println(m.getKey()+"---"+m.getValue());

 }

 //hashmap keySet() 遍歷

 for(Object m: hash.keySet()){

 System.out.println(m+"---"+hash.get(m));

 }

 // treemap keySet()遍歷

 for(Object m: treeMap.keySet()){

 System.out.println(m+"---"+treeMap.get(m));

 }

}

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