What is the correct way to implement a GridViewPager on Android Wear?

Question

I\'m trying to implement a GridViewPager so I can switch between 2 unique views. So far I haven\'t been able to add any views at all. Below is my code

public         


        

Answer 1

Stacktrace explanation:

First of all - the following line is wrong:

gridViewPager.addView(inflater.inflate(R.layout.selector_generic, stub));

inflate(int resource, ViewGroup root)
with root!=null is the same as
inflate(int resource, ViewGroup root, boolean attachToRoot) with last argument as true.

So according to the documentation it will inflate view from resource and attach it to root -> then return a root.

this will try to attach newly inflated view to stub, and then try to attach stub (result from inflate() with specified root) to the gridViewPager. But stub already has a parent (it's already attached to the view hierarchy in your activity). So this is an explanation of stacktrace:)
Please note that you should NOT add views to gridViewPager via .addView() methods - you should do it via adapter instead and that line should be removed.

GridPagerAdapter example:

Here is simple implementation for GridPagerAdapter;

private class MyGridViewPagerAdapter extends GridPagerAdapter {
    @Override
    public int getColumnCount(int arg0) {
        return 2;
    }

    @Override
    public int getRowCount() {
        return 2;
    }

    @Override
    protected Object instantiateItem(ViewGroup container, int row, int col) {
        final View view = LayoutInflater.from(getApplicationContext()).inflate(R.layout.grid_view_pager_item, container, false);
        final TextView textView = (TextView) view.findViewById(R.id.textView);
        textView.setText(String.format("Page:\n%1$s, %2$s", row, col));
        container.addView(view);
        return view;
    }

    @Override
    protected void destroyItem(ViewGroup container, int row, int col, Object view) {
        container.removeView((View)view);
    }

    @Override
    public boolean isViewFromObject(View view, Object object) {
        return view==object;
    }
}

Content of grid_view_pager_item.xml:

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="10dp">

    <TextView
        android:id="@+id/textView"
        android:layout_width="match_parent"
        android:layout_height="100dp"
        android:layout_gravity="center_vertical"
        android:gravity="center"
        android:background="#4400ff00"
        android:textColor="#000000"
        android:textSize="26sp"/> 

</FrameLayout>

Here is a final result of 2x2 grid. Two screens are in still state and two are pictured during the pages being half-scrolled:)

---

Looking for more?

This is just an example of using standard GridPagerAdapter. If you want more advanced one, with usage of FragmentGridPagerAdapter, CardFragments and pages backgrounds - please see the GridViewPager example located in platform samples:
{sdk_root}/samples/android-20/wearable/GridViewPager