import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

public class MapTest {

 public static void main(String[] args){
 Map<String,String> map = new HashMap<String,String>();
 for(Integer i=0;i<20;i++){
 map.put(i.toString(),i.toString());
 }
 Iterator<String> it = map.keySet().iterator();
 while (it.hasNext()){
 System.out.println(it.next());
 it.remove();
 }
 if(map.isEmpty()){
 System.out.print("map is empty");
 }else {
 System.out.print("map is not empty");
 }




 }


}