java中遍历MAP的几种方法

Java代码

Map<String,String> map=new HashMap<String,String>();

map.put("username",
"qq");

map.put("passWord",
"123");

map.put("userID",
"1");

map.put("email",
"qq@qq.com");

Map<String,String> map=new HashMap<String,String>();
map.put("username", "qq");
map.put("passWord", "123");
map.put("userID", "1");
map.put("email", "qq@qq.com");

第一种用for循环

Java代码

for(Map.Entry<String, String> entry:map.entrySet()){

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

}

for(Map.Entry<String, String> entry:map.entrySet()){
System.out.println(entry.getKey()+"--->"+entry.getValue());
}

第二种用迭代

Java代码

Set set = map.entrySet();
Iterator i = set.iterator();
while(i.hasNext()){

Map.Entry<String, String> entry1=(Map.Entry<String, String>)i.next();

System.out.println(entry1.getKey()+"=="+entry1.getValue());

}

Set set = map.entrySet();
Iterator i = set.iterator();
while(i.hasNext()){
Map.Entry<String, String> entry1=(Map.Entry<String, String>)i.next();
System.out.println(entry1.getKey()+"=="+entry1.getValue());
}

用keySet()迭代

Java代码

Iterator it=map.keySet().iterator();
while(it.hasNext()){

String key;
String value;
key=it.next().toString();
value=map.get(key);
System.out.println(key+"--"+value);

}

Iterator it=map.keySet().iterator();
while(it.hasNext()){
String key;
String value;
key=it.next().toString();
value=map.get(key);
System.out.println(key+"--"+value);
}

用entrySet()迭代

Java代码

Iterator it=map.entrySet().iterator();
System.out.println( map.entrySet().size());
String key;
String value;
while(it.hasNext()){

Map.Entry entry = (Map.Entry)it.next();
key=entry.getKey().toString();
value=entry.getValue().toString();
System.out.println(key+"===="+value);

}