OnClickListener for Buttons in GridView

Question

I have a GridView adapter displaying a grid of Buttons. Now I want to set up an OnClickListener for my buttons but of course they don't have their own R.id I can access as they are added to the grid via the adapter, rather than a layout.xml.

I tried to use OnItemClickListener as follows:

m_onItemClickListener = new OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> adapterView, View view, int pos, long l) {
            switch(pos) {
                case MyConstants.POS_OF_BUTTON_1:
                        // Do stuff...
                    break;
                case MyConstants.POS_OF_BUTTON_2:
                        // Do stuff...
                    break;
            }
        }
    };

But to my understanding you can't use a clickable or focusable item with OnItemClickListener. How do I get round this? Thanks!

Answer 1

There are more elegant ways to do this whole thing (starting from using a RecyclerView with a GridLayoutManager instead of a GridView), but if you're looking for the quick and easy solution to use with what you already have, this is what you can do:

First of all, you should set some ID on your buttons, they don't have to come from R.id (although it would be preferable if you inflated the views from a layout, with an ID defined there, and used a ViewHolder).

Worst case, you can just define constants in your adapter for the IDs you want to use for each kind of button (e.g. static final int DELETE_BUTTON = 1;), and then set these IDs on the buttons manually, in code.

Then you can pass a simple OnClickListener (not OnItemClickListener), which handles clicks of all these different buttons in a single item, to your adapter, and make the adapter set the listener on each of these buttons, for each of the item views in the grid.

You will also need to set the position of the item as a tag on the button view itself, so that when the click happens, you can determine for which item the click happened.

Sample code as follows:

View.OnClickListener listener = new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        Object tag = v.getTag();
        if (!(tag instanceof Integer)) {
            // Show error message or just throw an exception.
        }
        int position = (Integer) tag;
        // We get the item at this position, to know which one to use
        Item item = adapter.getItem(position);
        switch (v.getId()) {
            case DELETE_BUTTON:
                // Delete stuff here
                break;
            case EDIT_BUTTON:
                // Edit stuff here
                break;
            ...
        }
    }
};

adapter.setOnClickListener(listener);

Then, in the getView method of the adapter, you need to set this listener on each of the buttons and also set the position of the item as a tag on the buttons. This way, you will be able to figure out to which item the button belongs to, in the listener code above.

@Override
public View getView(int i, View view, ViewGroup viewGroup) {
    ...
    deleteButton.setId(DELETE_BUTTON);
    deleteButton.setOnClickListener(listener);
    deleteButton.setTag(i);
    ...
}

In general, I sincerely urge you to also look into the ViewHolder pattern, and RecyclerView and GridLayoutManager when you have time. Most of this will translate there as well.

EDIT

In order to make multiple Views clickable/focusable inside a list/grid item, you need to set the descendantFocusability attribute to blocksDescendants on the root view of the item, either simply in the XML, or in code via:

viewGroup.setDescendantFocusability(ViewGroup.FOCUS_BLOCK_DESCENDANTS);