Map遍历方法

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

Java代码

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()

Java代码

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()

Java代码

for (Map.Entry<String, String> m : emails.entrySet()) {

 

logger.info("email-" m.getKey() ":" m.getValue());

}

// 方法三：用keySet()

Java代码

Iterator it = emails.keySet().iterator();

while (it.hasNext()){

String key;

key=(String)it.next();

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

}

// 方法四：jdk1.5支持,用keySEt()和For-Each循环

Java代码

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
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

Java代码

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);