java中map集合的用法

1.声明一个map: Map map = new HashMap();

2.向map中放值,注意：map是key-value的形式存放的.如:     

map.put("sa","dd");

3.从map中取值:

String str = map.get("sa").toString();

结果是:str = "dd";

4.遍历一个map，从中取得key 和value

JDK1.5

Map   m   =   new   HashMap();
for   (Object   o   :   map.keySet())   {
map.get(o);
}

 

JDK1.4

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()   ;
}