problem in gridview while scrolling

[Suzzane Pinto]

hi all...

Iam stuck with a strange problem since long...
i have a gridview with images and checkbox and the problem is after selecting the image with checkbox when i scroll down..the above selected checkboxes become uncheckd...
i have no idea why this is happening....my code for the adapter class is like

public class BookAdapter1 extends BaseAdapter {
public boolean[] thumbnailsselection;
private Bitmap[] thumbnail=CreateBook.arlr1.toArray(new Bitmap[CreateBook.arlr1.size()]);;
	 public static Integer [] mobileValues = CreateBook.id.toArray(new Integer[CreateBook.id.size()]);
	
	public BookAdapter1(Context context) {
		mInflater = (LayoutInflater) context
				.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
	}


 
	public View getView(int position, View convertView, ViewGroup parent) {
		ViewHolder holder;
		this.thumbnailsselection = new boolean[CreateBook.id.size()];
		
		if (convertView == null) {
			holder = new ViewHolder();
			
			convertView = mInflater.inflate(
					R.layout.galleryitem, null);
			holder.imageview = (ImageView) convertView.findViewById(R.id.thumbImage);
			holder.checkbox = (CheckBox) convertView.findViewById(R.id.itemCheckBox);
			
			convertView.setTag(holder);
		}
		else {
			holder = (ViewHolder) convertView.getTag();
		}
		holder.checkbox.setId(position);
		holder.imageview.setId(position);
		holder.checkbox.setOnClickListener(new OnClickListener() {
			
			public void onClick(View v) {
				// TODO Auto-generated method stub
				CheckBox cb = (CheckBox) v;
				int id = cb.getId();
				
				if (thumbnailsselection[id]){
					cb.setChecked(false);
					thumbnailsselection[id] = false;
				} else {
					cb.setChecked(true);
					thumbnailsselection[id] = true;
				}
			}
		});
		holder.imageview.setImageBitmap(thumbnail[position]);
		holder.checkbox.setChecked(thumbnailsselection[position]);
		holder.id = position;

		return convertView;
public int getCount() {
		return CreateBook.id.size();
	}
 

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

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

looking for the hint...which could solve my issue....
i would be really greatful

thankyou

[James Do]

these scrolling view reuse Views rather than continuing to create a new one for every item in the list (or grid)
Therefore if your device is able to fit 15 items on the screen, you will only be asked to create 15 views. If you scroll up so that the top row disappears, those Views will be reused on the bottom row rather than requiring new Views to be created.

Coming back to your code, it should now be obvious that you set the checked state when the View is created, but not when it is reused.
Rather than relying on the View to maintain the checked state you should have a custom object associated with the current view and update the custom object when the check state changes.