Android GridView Multiple Selection

Question

I have a GridView implemented and activated the

mGridView.setChoiceMode(GridView.CHOICE_MODE_MULTIPLE_MODAL);

mode. Now I have the possibility to select multiple items from my grid when I perform a long click on one item. I want to achieve this behavior on a normal, short click. Is this possible?

Answer 1

First, I'd suggest to think if this user scenario is what you have been looking for. By default, in Android UX to select something you do long press and it's a pattern users used to. So, maybe you should rethink the whole flow.

Saying that, do you actually need GridView.CHOICE_MODE_MULTIPLE_MODAL?

You can handle it on the Adapter level, by just storing selected positions and update this list in onClick handler:

static final String[] numbers = new String[] {
        "A", "B", "C", "D", "E",....
        "U", "V", "W", "X", "Y", "Z"};

.....

gridView = (GridView) findViewById(R.id.gridView1);
final CustomAdapter adapter = new CustomAdapter(numbers);
gridView.setAdapter(adapter);
gridView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
    public void onItemClick(AdapterView<?> parent, View v,
                            int position, long id) {
        int selectedIndex = adapter.selectedPositions.indexOf(position);
        if (selectedIndex > -1) {
            adapter.selectedPositions.remove(selectedIndex);
            ((CustomView)v).display(false);
        } else {
            adapter.selectedPositions.add(position);
            ((CustomView)v).display(true);
        }
    }
});

Custom BaseAdapter to display Custom views:

public class CustomAdapter extends BaseAdapter {
    private String[] strings;
    List<Integer> selectedPositions = new ArrayList<>();

    CustomAdapter(String [] strings) {
        this.strings = strings;
    }

    @Override
    public int getCount() {
        return strings.length;
    }

    @Override
    public Object getItem(int position) {
        return strings[position];
    }

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

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        CustomView customView = (convertView == null) ? 
                                    new CustomView(MainActivity.this) : (CustomView) convertView;
        customView.display(strings[position], selectedPositions.contains(position));
        return customView;
    }
}

Custom View (in my case - cell with TextView). Xml:

<merge xmlns:android="http://schemas.android.com/apk/res/android">
    <TextView
        android:id="@+id/textView"
        android:textColor="#FFF"
        android:gravity="center"
        android:layout_width="match_parent"
        android:layout_height="60dp" />
</merge>

Code:

class CustomView extends FrameLayout {

    TextView textView;

    public CustomView(Context context) {
        super(context);
        LayoutInflater.from(context).inflate(R.layout.custom_view, this);
        textView = (TextView)getRootView().findViewById(R.id.textView);
    }

    public void display(String text, boolean isSelected) {
        textView.setText(text);
        display(isSelected);
    }

    public void display(boolean isSelected) {
        textView.setBackgroundColor(isSelected? Color.RED : Color.LTGRAY);
    }
}