Java如何遍历Map的所有的元素
2013-12-09 23:47
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JDK1.4中
[java]
view plaincopyprint?
<font color="#0000ff">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();
}</font>
JDK1.5中,应用新特性For-Each循环
[java]
view plaincopyprint?
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。
[java]
view plaincopyprint?
<font color="#0000ff">private Hashtable<String, String> emails =
new Hashtable<String, String>();</font>
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
[java]
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<font color="#0000ff">//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));
}
</font>
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]
view plaincopyprint?
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));
}
}
以上内容转自网络:/article/7870901.html
[java]
view plaincopyprint?
<font color="#0000ff">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();
}</font>
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]
view plaincopyprint?
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 中的每个元素都是一个 Map.Entry 类型。
[java]
view plaincopyprint?
<font color="#0000ff">private Hashtable<String, String> emails =
new Hashtable<String, String>();</font>
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
[java]
view plaincopyprint?
<font color="#0000ff">//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));
}
</font>
//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 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]
view plaincopyprint?
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));
}
}
以上内容转自网络:/article/7870901.html
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