import java.util.*;
public class Ex3 { /**
 * @param args
 */
public static void main(String[] args) {
// TODO 自动生成方法存根
HashMap capital=new HashMap();
capital.put("beijing","china" ); 
capital.put("roma","italy" );
Set key=capital.keySet();
System.out.println("key:");
printElements(key);
System.out.println("values:");
Collection c=capital.values();
printElements(c);
Set entry=capital.entrySet();
//printElements(entry);
Iterator i=entry.iterator();
while(i.hasNext())
Map.Entry me=(Map.Entry)i.next();
System.out.println(me.getKey()+"="+me.getValue());




}

static void printElements(Collection c)
{
Iterator i=c.iterator();
while(i.hasNext())
 System.out.println(i.next());
}
}错误信息:
无法解析Map.Entry大家帮忙看看