problem in loading image on clicking back button

hii, in my android application there are number of images in drawable folder. in my layout two buttons: back and forward button.on clicking next and back buttons different-2 image get loaded on the same layout(common for all images). Problem:i am able to load images in next/back button click but after reaching to the last image i want to make my next button click disable and same for the back button.As the user is on the first image the back button would be disable .Code is as:

public class SequencerActivity extends Activity implements OnClickListener

{ private int imageCounter = 0; private ImageView imageLoader;

private int[] imageList = {R.drawable.image_wo_lbl_0, R.drawable.image_wo_lbl_1, R.drawable.image_wo_lbl_2, R.drawable.image_wo_lbl_3, R.drawable.image_wo_lbl_4, R.drawable.image_wo_lbl_5,
        R.drawable.image_wo_lbl_6, R.drawable.image_wo_lbl_8, R.drawable.image_wo_lbl_9,R.drawable.image_wo_lbl_10, R.drawable.image_wo_lbl_11};
@Override
public void onCreate(Bundle savedInstanceState) 
{
    setContentView(R.layout.parent_frame);//this one is the common parent layout for all image views
    super.onCreate(savedInstanceState);

    /*requestWindowFeature(Window.FEATURE_NO_TITLE);
    getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
    WindowManager.LayoutParams.FLAG_FULLSCREEN);*/

    //int image1 = R.drawable.image_w_lbl_0;

    imageLoader = (ImageView) findViewById(R.id.imageLoader);
    //imageLoader.setImageResource(image1);

    ImageButton next = (ImageButton) findViewById(R.id.next);
    ImageButton back = (ImageButton) findViewById(R.id.back);
    next.setOnClickListener(this);
    back.setOnClickListener(this);
    //show the default image
    this.loadImage(imageList[imageCounter]);

}
@Override
public void onClick(View v) 
{
    int imagePath = 0;
    // TODO Auto-generated method stub
    switch (v.getId())
    {
    case R.id.next:
        Log.i("Tag","tag");
        if(imageCounter < imageList.length)
        {
            imageCounter++;
            imagePath = imageList[imageCounter];
            if (imageCounter==(imageList.length)-1)
            {
                //**how to make my next button disable for last image**
            }
        }
        break;
    case R.id.back:
        if(imageCounter > 0)
        {
            imageCounter--;
            imagePath = imageList[imageCounter];
            if (imageCounter==0)
            {
                //**how to make my back button disable for 1st image**
            }
      开发者_StackOverflow中文版  }
        break;
    }
    this.loadImage(imagePath);

}

private void loadImage(int imagePath)
{
    imageLoader.setImageResource(imagePath);

}

}

help please.Thanks.

when you have the onClick event for back your forgetting to decrement your counter

case R.id.back:
        if(imageCounter > 0)
        {
            imageCounter --;
            imagePath = imageList[imageCounter];
        }
        break;
    }

without that your always loading the same image