Databases
StackOverflow2013
Postsdbo
POAndroid ViewPager and ListViews
Body
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POAndroid ViewPager and ListViews
    text
    copied!<p>I'm relatively new to Android development and development overall. I'm having trouble grasping the syntax/process for ViewPager. </p> <p>I have several ListViews that I want to implement into a ViewPager. I've got the compatibility pack loaded and everything. But I haven't seen any complete examples of how to do this. </p> <p>I learn best by looking at examples. If someone can post an examples of any projects you've implemented this sort of thing in, please let me know. </p> <p>The issue is that I get a Null Pointer Exception on this line when trying to launch my activity: </p> <pre><code>listView1.setAdapter(new ArrayAdapter&lt;Object&gt;(this, R.layout.rowlayout, list1)); </code></pre> <p>I suspect that I'm just doing this all wrong. If I don't use the ViewPager, I can get both lists to display their content. So I know the lists aren't null...</p> <p>EDIT:</p> <p>Thanks to VenomM for the answer below! Here's the code I ended up using, slightly modified from VenomM's examples.</p> <p>ViewPagerAdapter:</p> <pre><code>public class ViewPagerAdapter extends PagerAdapter implements TitleProvider { private ListView listView1; private static String[] titles = new String[] { "Page 1", "Page 2", "Page 3", }; private final Context context; public ViewPagerAdapter( Context context ) { this.context = context; } @Override public String getTitle( int position ) { return titles[ position ]; } @Override public int getCount() { return titles.length; } @Override public Object instantiateItem(View collection, int position) { LayoutInflater layoutInflater = ((Activity) context).getLayoutInflater(); listView1 = (ListView) layoutInflater.inflate(R.layout.listview1, null); String[] listData = null; MyArrayAdapter dataAdapter; if (position == 0) { listData = context.getResources().getStringArray(R.array.list1); dataAdapter = new MyArrayAdapter((Activity) context, R.layout.rowlayout, listData); } else if (position == 1) { listData = context.getResources().getStringArray(R.array.list2); dataAdapter = new MyArrayAdapter((Activity) context, R.layout.rowlayout, listData); } else { listData = context.getResources().getStringArray(R.array.list3); dataAdapter = new MyArrayAdapter((Activity) context, R.layout.rowlayout, listData); } listView1.setAdapter(dataAdapter); listView1.setOnItemClickListener(new OnItemClickListener() { @Override public void onItemClick(AdapterView&lt;?&gt; adapter, View view, int position, long arg3) { Toast.makeText(context, adapter.getAdapter().getItem(position).toString(), Toast.LENGTH_LONG).show(); } }); ((ViewPager) collection).addView(listView1, 0); return listView1; } @Override public void destroyItem(View collection, int position, Object view) { System.out.println("on destroyItem()"); ((ViewPager) collection).removeView((ListView) view); } @Override public boolean isViewFromObject(View view, Object object) { System.out.println("on isViewFromObject()"); return view == ((ListView) object); } @Override public void finishUpdate( View view ) {} @Override public void restoreState( Parcelable p, ClassLoader c ) {} @Override public Parcelable saveState() { return null; } @Override public void startUpdate( View view ) {} } </code></pre> <p>ArrayAdapter:</p> <pre><code>public class MyArrayAdapter extends ArrayAdapter&lt;String&gt;{ private Activity context = null; private String[] names = null; private int rowLayoutId; public MyArrayAdapter(Activity context, int textViewResourceId, String[] names) { super(context, textViewResourceId, names); this.context = context; this.names = names; this.rowLayoutId =textViewResourceId; } // static to save the reference to the outer class and to avoid access to // any members of the containing class static class ViewHolder { protected ImageView imageView; protected TextView textView; } } </code></pre>
 

Querying!

 
Guidance
An individual column

Larger individual text columns get their own page to allow for proper reading.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload