Android: Change Button background in ListView Row

问题:

My rows contain a button that has its own click listener set in my adapter's getView. I'm able to distinguish between my button clicks and the actual row item clicks using android:descendantFocusability="blocksDescendants" in the row's parent.

When I click on a button it sets the button background properly, my problem is as I scroll through the list its setting it for different rows as well. I assume theirs an issue somewhere with views recycling.

Here's my code:

@Override
public View getView(int position, View convertView, ViewGroup parent){

    if(convertView == null){

        holder = new ViewHolder();

        convertView = inflater.inflate(R.layout.todays_sales_favorite_row, null);
        holder.favCatBtn = (Button)convertView.findViewById(R.id.favCatBtn);            

        convertView.setTag(holder);

    } else {
        holder = (ViewHolder)convertView.getTag();
    }

        holder.favCatBtn.setTag(position);
        holder.favCatBtn.setOnClickListener(this);

    return convertView;
 }

@Override
public void onClick(View v) {
    int pos = (Integer) v.getTag();
    Log.d(TAG, "Button row pos click: " + pos);
    RelativeLayout rl = (RelativeLayout)v.getParent();
    holder.favCatBtn = (Button)rl.getChildAt(0);
    holder.favCatBtn.setBackgroundResource(R.drawable.icon_yellow_star_large);

}

So if i click on the button at row position 1 the button background changes as it should. But then as i scroll down the list random other buttons are getting set as well. Then sometimes when I scroll back up to position 1 the button background reverts back to the original again.

What am I missing here? I know I'm right there its just something minor I'm not doing.

回答1:

Yes, you are right, the views are recycled. You will need to track which positions have been clicked on and update the background resource in your getView method. For example, I extended your code to add background toggling:

private final boolean[] mHighlightedPositions = new boolean[NUM_OF_ITEMS];

@Override
public View getView(int position, View convertView, ViewGroup parent){

    if(convertView == null){
        holder = new ViewHolder();
        convertView = inflater.inflate(R.layout.todays_sales_favorite_row, null);
        holder.favCatBtn = (Button)convertView.findViewById(R.id.favCatBtn);
        holder.favCatBtn.setOnClickListener(this);
        convertView.setTag(holder);
    }else {
        holder = (ViewHolder)convertView.getTag();
    }

    holder.favCatBtn.setTag(position);

    if(mHighlightedPositions[position]) {
        holder.favCatBtn.setBackgroundResource(R.drawable.icon_yellow_star_large);
    }else {
        holder.favCatBtn.setBackgroundResource(0);
    }

    return convertView;
}

@Override
public void onClick(View view) {
    int position = (Integer)view.getTag();
    Log.d(TAG, "Button row pos click: " + position);

    // Toggle background resource
    RelativeLayout layout = (RelativeLayout)view.getParent();
    Button button = (Button)layout.getChildAt(0);
    if(mHighlightedPositions[position]) {
        button.setBackgroundResource(0);
        mHighlightedPositions[position] = false;
    }else {
        button.setBackgroundResource(R.drawable.icon_yellow_star_large);
        mHighlightedPositions[position] = true;
    }
}

回答2:

I found a perfect, short and clean solution for this using StateListDrawable:

@Override
public View getView(final int position, View convertView, ViewGroup parent) {
    currentPosition = position;
    holder = null;
    if (convertView == null) {
        holder = new Holder();
        LayoutInflater vi = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        convertView = vi.inflate(R.layout.grid_item, null);
        holder.imageView = (ImageView) convertView.findViewById(R.id.gridItemBtn);

        StateListDrawable states = new StateListDrawable();
        states.addState(new int[] {android.R.attr.state_pressed},
                ContextCompat.getDrawable(context, R.drawable.pressed_state));
        states.addState(new int[] {android.R.attr.state_focused},
                ContextCompat.getDrawable(context, R.drawable.focused_state));
        states.addState(new int[]{},
                ContextCompat.getDrawable(context, R.drawable.default_state));
        holder.imageView.setImageDrawable(states);
    }

    return convertView;
}

This works still perfect together with OnClickListener where you can do your important stuff.

回答3:

holder.btnUnLock.setOnClickListener(new OnClickListener() {

  @Override
  public void onClick(View v) {
 // TODO Auto-generated method stub
 // Button btn = Button(v);
   holder = (ViewHolder) v.getTag();
   holder.btnSetLock.setBackgroundResource(R.drawable.btn_lock_bg_right);
holder.btnUnLock.setBackgroundResource(R.drawable.btn_unlock_bg_left);

}
});