CODEWITHSUNDEEP
androidgridviewbaseadapter
jalv1039
jalv1039

Reputation: 1682

Setting visible to elements that were invisible before in GridView

I have a GridView in which I want to always show 7 icons, and sometimes an additional icon depending on a request. In the beginning the additional icon is never shown. This is the structure:

0   1   2
3   4   5
6  [7]

All the icons fit into the screen so I don't need/have scroll. Each icon is composed by an image and a text.

For this, I have a CustomAdapter which extends BaseAdapter. I have overriden the getView method in which I set the text and the image for each icon.

public View getView(int position, View convertView, ViewGroup parent) {
    View v = null;

    if (convertView == null) {
        LayoutInflater li = ((Activity) context).getLayoutInflater();
        v = li.inflate(R.layout.icon, null);
    } else {
        v = convertView;
    }

    TextView tv = (TextView) v.findViewById(R.id.icon_textView);
    tv.setText(position);
    ImageView iv = (ImageView) v.findViewById(R.id.icon_ImageView);
    iv.setImageResource(imageResourcesArray[position]);

    if ((position == ADDITIONAL_ICON)) && !showAdditionalIcon) {
        v.setVisibility(View.INVISIBLE);
    }

    return v;
}

The imageResourcesArray[] is an array of integers with the image resources. The other functions and variables in the CustomAdapter are:

public static final int ADDITIONAL_ICON = 7;
private boolean showAdditionalIcon = false;

public showAdditionalIcon(){
    this.showAdditionalIcon = true;
    notifyDataSetChanged();
    // notifyDataSetInvalidated();
}

public hideAdditionalIcon(){
    this.showAdditionalIcon = false;
    notifyDataSetChanged();
    // notifyDataSetInvalidated();
}

Later on, I create and set the CustomAdapter to the GridView from a class which extends Activity (say ClassA):

    GridView grid = (GridView) findViewById(R.id.main_gridView);
    customAdapter = new CustomAdapter(this);
    grid.setAdapter(customAdapter);

My problem appears when after some calculations and requests to a server, I have to show the additional icon (number 7). So I call (from ClassA):

    customAdapter.showAdditionalIcon();

Now, the additional icon appears, but the first icon disappears... I have tried to use notifyDataSetInvalidated() and notifyDataSetChanged() but both had the same result.

Of course, I could generate a new CustomAdapter with the additional icon allowed, but I would preffer not to do it...

Thanks in advance.

Upvotes: 3

Views: 4332

Answers (1)

yjw
yjw

Reputation: 3444

I'm not sure if this counts as an answer for you. Root of the problem seems to be the convertView we are using. I did not dig so deep into Android source, but I think there is no guarantee on how views are reused even it is obvious that all views are already visible and there should be no reuse behind the scenes.

What this means is that the view we linked to position 7 as we visualize this whole scenario is actually reused later at position 0. Since your code does not explicitly reset a view to be visible, the view will be reused with visibility set to INVISIBLE, thus the mystery of the disappearing first item.

Simplest solution should be as @Vinay suggest above, by explicitly setting to View.VISIBLE.

if ((position == ADDITIONAL_ICON))) {
    if (!showAdditionalIcon)
        v.setVisibility(View.INVISIBLE);
    else
        v.setVisibility(View.VISIBLE);
}

Hope this helps, but I'm really hoping some Android expert pops by to tell us more about how this whole thing of reusing old views actually works.

Upvotes: 1

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