메인에서 이 화면으로 오는건 되는데
이화면에서 다시 메인으로 가니 에러가 뜨네요
에러 좀 잡아주세요...

12-17 03:05:48.937: ERROR/AndroidRuntime(13180): Uncaught handler: thread main exiting due to uncaught exception
12-17 03:05:48.987: ERROR/AndroidRuntime(13180): java.lang.RuntimeException: Unable to start activity ComponentInfo{exam.project/exam.project.Main}: java.lang.NullPointerException
12-17 03:05:48.987: ERROR/AndroidRuntime(13180):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2496)
12-17 03:05:48.987: ERROR/AndroidRuntime(13180):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2512)
12-17 03:05:48.987: ERROR/AndroidRuntime(13180):     at android.app.ActivityThread.access$2200(ActivityThread.java:119)
12-17 03:05:48.987: ERROR/AndroidRuntime(13180):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1863)
12-17 03:05:48.987: ERROR/AndroidRuntime(13180):     at android.os.Handler.dispatchMessage(Handler.java:99)
12-17 03:05:48.987: ERROR/AndroidRuntime(13180):     at android.os.Looper.loop(Looper.java:123)
12-17 03:05:48.987: ERROR/AndroidRuntime(13180):     at android.app.ActivityThread.main(ActivityThread.java:4363)
12-17 03:05:48.987: ERROR/AndroidRuntime(13180):     at java.lang.reflect.Method.invokeNative(Native Method)
12-17 03:05:48.987: ERROR/AndroidRuntime(13180):     at java.lang.reflect.Method.invoke(Method.java:521)
12-17 03:05:48.987: ERROR/AndroidRuntime(13180):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860)
12-17 03:05:48.987: ERROR/AndroidRuntime(13180):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
12-17 03:05:48.987: ERROR/AndroidRuntime(13180):     at dalvik.system.NativeStart.main(Native Method)
12-17 03:05:48.987: ERROR/AndroidRuntime(13180): Caused by: java.lang.NullPointerException
12-17 03:05:48.987: ERROR/AndroidRuntime(13180):     at exam.project.Main.onCreate(Main.java:38)
12-17 03:05:48.987: ERROR/AndroidRuntime(13180):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
12-17 03:05:48.987: ERROR/AndroidRuntime(13180):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2459)
12-17 03:05:48.987: ERROR/AndroidRuntime(13180):     ... 11 more
package exam.project;
import java.io.File;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.widget.*;
public class Main extends Activity {
 
 
  int num = 0;
  String id_num = "";
     String url_location = "";
     String enterance_money = "";
     String image_location = "";
     String college_name = "";
     Drawable[] d = {null,null,null,null,null,null,null,null};
 
 
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        Intent intent = super.getIntent();
        college_name = intent.getStringExtra("college_name");
        
        
        
        Search.cursor.moveToFirst();
        while(!Search.cursor.isLast()){
         if(college_name.equals(Search.cursor.getString(Search.cursor.getColumnIndex("college_name")))){
          id_num = Search.cursor.getString(Search.cursor.getColumnIndex("_id"));
          enterance_money = Search.cursor.getString(Search.cursor.getColumnIndex("enterance_money"));
          image_location = Search.cursor.getString(Search.cursor.getColumnIndex("image_location"));
          url_location = Search.cursor.getString(Search.cursor.getColumnIndex("this_year_url"));
//          Log.i("id_num",id_num);
//          Log.i("enterance_money",enterance_money);
//          Log.i("image_file.length",image_location);
//          Log.i("url_location",url_location);
 //         num = Integer.parseInt(id_num);
          break;
         } 
         Search.cursor.moveToNext();
        }
        
        File folder = new File(image_location);
        
        File[] image_file = folder.listFiles();
        
        ImageView emble = (ImageView)findViewById(R.id.emblem);
        ImageView name_image = (ImageView)findViewById(R.id.name);
        ImageView map_image2 = (ImageView)findViewById(R.id.map_image2);
        
        d[0] = Drawable.createFromPath(image_file[0].getAbsolutePath());
        d[1] = Drawable.createFromPath(image_file[1].getAbsolutePath());
        d[2] = Drawable.createFromPath(image_file[2].getAbsolutePath());
        d[3] = Drawable.createFromPath(image_file[3].getAbsolutePath());
        d[4] = Drawable.createFromPath(image_file[4].getAbsolutePath());
        d[5] = Drawable.createFromPath(image_file[5].getAbsolutePath());
        d[6] = Drawable.createFromPath(image_file[6].getAbsolutePath());
        d[7] = Drawable.createFromPath(image_file[7].getAbsolutePath());
        
        emble.setBackgroundDrawable(d[0]);
        map_image2.setBackgroundDrawable(d[1]);
        name_image.setBackgroundDrawable(d[7]);
        
        
        final ViewFlipper vf1 = (ViewFlipper)findViewById(R.id.ViewFlipper01);
        ImageView map_image = (ImageView)findViewById(R.id.map_image);
        map_image.setOnClickListener(new View.OnClickListener() {
   
   public void onClick(View v) {
    // TODO Auto-generated method stub
    vf1.setDisplayedChild(1);
   }
  });
        
        ImageView college_scean = (ImageView)findViewById(R.id.college_scean);
        college_scean.setOnClickListener(new View.OnClickListener() {
   
   public void onClick(View v) {
    // TODO Auto-generated method stub
    vf1.setDisplayedChild(0);
   }
  });
        
        
        ImageButton url_button = (ImageButton)findViewById(R.id.url_button);
        url_button.setOnClickListener(new View.OnClickListener() {
   
   public void onClick(View v) {
    // TODO Auto-generated method stub
    Intent intent;
    intent = new Intent(Main.this, url_page.class);
    intent.putExtra("url_location", url_location);
       startActivity(intent);
       overridePendingTransition(R.anim.fade, R.anim.hold);
    
    
   }
  });
        
        Gallery g = (Gallery)findViewById(R.id.gallery);
        g.setAdapter(new ImageAdapter2(this));
        
        findViewById(R.id.page2_button).setOnClickListener(mClickListener);
        findViewById(R.id.page3_button).setOnClickListener(mClickListener);
        findViewById(R.id.page4_button).setOnClickListener(mClickListener);
    }
    
    Button.OnClickListener mClickListener = new View.OnClickListener(){
//     @Override
     public void onClick(View v){
      Intent intent;
      
      switch(v.getId()){
      case R.id.page2_button:
       intent = new Intent(Main.this, Page2.class);
       intent.putExtra("_id", id_num);
       startActivity(intent);
       overridePendingTransition(R.anim.fade, R.anim.hold);
       break;
      case R.id.page3_button:
       intent = new Intent(Main.this, Page3.class);
       intent.putExtra("_id", id_num);
       startActivity(intent);
       overridePendingTransition(R.anim.fade, R.anim.hold);
       break;
      case R.id.page4_button:
       intent = new Intent(Main.this, Page4.class);
       intent.putExtra("_id", id_num);
       startActivity(intent);
       overridePendingTransition(R.anim.fade, R.anim.hold);
       break;
      }
     }
    };
    
    
    class ImageAdapter2 extends BaseAdapter  {
        private Context mContext;
        private int[] mImageIds = {
                R.drawable.t01,
                R.drawable.t01,
                R.drawable.t01,
                R.drawable.t01,
                R.drawable.t01
        };
        public ImageAdapter2(Context c)  {
                mContext = c;
        }
        public int getCount()  {
                return mImageIds.length;
        }
        public Object getItem(int position)  {
            return mImageIds[position];
    }
    public long getItemId(int position)  {
            return position;
    }        
    public View getView(int position, View convertView, 
                                       ViewGroup parent)  {
            ImageView imageView;
            if (convertView == null)  {
                    imageView = new ImageView(mContext);
            } else  {
                    imageView = (ImageView)convertView;
            }
            //imageView.setImageResource(mImageIds[position]);
            imageView.setBackgroundDrawable(d[position+2]);
            imageView.setScaleType(ImageView.ScaleType.FIT_XY);
            imageView.setLayoutParams(new Gallery.LayoutParams(136, 88));
            return imageView;
    }
    }
    
    @Override
    public void onPause(){
     super.onPause();
    }
}