안드로이드를 처음 접하며 거기다 자바라도 잘하는 것도 아니고..
그래서 안드로이드 공식 홈페이지에서 예제를 보며 공부하고 잇습니다.
문제는 GridView를 하고 있는데요
아래처럼 에러가 나와요...혼자 끙끙거리다가 여기까지와서 여쭤봅니다..이게 무슨 에러인가요?
해결방법을 알려주시겠습니까?ㅠ 
==========Java==============================
package com.android.photo;

import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewGroup.LayoutParams;
import android.widget.BaseAdapter;
import android.widget.GridView;
import android.widget.ImageView;


public class GridViewTest extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
       
        GridView gridview = (GridView) findViewById(R.id.gridview);
        gridview.setAdapter(new ImageAdapter(this));
    }     
    
    public class ImageAdapter extends BaseAdapter {
        private Context mContext;

        public ImageAdapter(Context c) {
            mContext = c;
        }

        public int getCount() {
            return mThumbIds.length;
        }

       public Object getItem(int position) {
            return null;
        }

       public long getItemId(int position) {
            return 0;
        }

    public View getView(int position, View convertView, ViewGroup parent) {
            ImageView imageView;
            if (convertView == null) {  // if it's not recycled, initialize some attributes
                imageView = new ImageView(mContext);
                imageView.setLayoutParams(new LayoutParams(85, 85));
                imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
                imageView.setPadding(8, 8, 8, 8);
            } else {
                imageView = (ImageView) convertView;
            }

            imageView.setImageResource(mThumbIds[position]);
            return imageView;
        }

      private Integer[] mThumbIds = {
                R.drawable.sample_2, R.drawable.sample_3,
                R.drawable.sample_4, R.drawable.sample_5,
                R.drawable.sample_6, R.drawable.sample_7,
                R.drawable.sample_8, R.drawable.sample_9,
                R.drawable.sample_10, R.drawable.sample_11
                };
    }   
}
==============xml====================================
<?xml version="1.0" encoding="utf-8"?>

 <GridView xmlns:android="http://schemas.android.com/apk/res/android"
  android:id="@+id/gridview"
  android:stretchMode="columnWidth"
  android:gravity="center"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  android:verticalSpacing="10dp"
  android:horizontalSpacing="10dp"
  android:numColumns="auto_fit">
 </GridView>
=============Error===================================
GridViewerror.jpg androidError.jpg