type Iterator does not take parameters

在ubuntu编译java程序时报错:type Iterator does not take parameters

源码如下:

package object;
import java.util.*;
class Generate{
    Map<Integer,String> map = new HashMap<Integer, String>();
    {
        map.put(,"mother");
        map.put(,"wife");
        map.put(,"father");
    }
    public String next()
    {
        Random rand = new Random();
        int i = rand.nextInt() + ;
        return map.get(i);
    }
}

public class Iterator1{
    public static void main(String[] args)
    {
        Generate g = new Generate();
        Collection<String> cll = new ArrayList<String>();
        for( int i = ; i < ; i++)
            cll.add(g.next());
        Iterator<String> iterator = cll.iterator();
        while(iterator.hasNext())
            System.out.println(iterator.next());
        System.out.println();
    }
}

报错原因:包里面有之前编写的一个Iterator类,编译时优先调用了包里的Iterator而没有调用java.util里面的Iterator