Using SwipeListView NullPointerException

Question

I am trying to use SwipeListView , but when I touch an item in my application, it will crash, the log information is:

 05-26 21:52:26.545: E/AndroidRuntime(19862): java.lang.NullPointerException 05-26 21:52:26.545: E/AndroidRuntime(19862): at com.fortysevendeg.android.swipelistview.SwipeListViewTouchListener.setFrontView(SwipeListViewTouchListener.java:121) 05-26 21:52:26.545: E/AndroidRuntime(19862): at com.fortysevendeg.android.swipelistview.SwipeListViewTouchListener.onTouch(SwipeListViewTouchListener.java:485) 05-26 21:52:26.545: E/AndroidRuntime(19862): at com.fortysevendeg.android.swipelistview.SwipeListView.onInterceptTouchEvent(SwipeListView.java:481) 

I use it step by step

 import android.app.Activity; import android.os.Bundle; import com.fortysevendeg.android.swipelistview.SwipeListView; import com.mkyong.android.adaptor.MobileArrayAdapter; public class ListMobileActivity extends Activity { static final String[] MOBILE_OS = new String[] { "Android", "iOS", "WindowsMobile", "Blackberry"}; MobileArrayAdapter myad ; private SwipeListView swipeListView; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.mainactivity); swipeListView =(SwipeListView)findViewById(R.id.book_listview); myad=new MobileArrayAdapter(this, MOBILE_OS); swipeListView.setAdapter(myad); } } 

Here is my layout file

 <?xml version="1.0" encoding="UTF-8"?> android:id="@+id/LinearLayoutListView" android:layout_width="fill_parent" android:layout_height="fill_parent" android:background="#FFFFFF" > xmlns:swipe="http://schemas.android.com/apk/res-auto" android:id="@+id/book_listview" android:layout_width="fill_parent" android:layout_height="wrap_content" android:listSelector="#00000000" swipe:swipeActionLeft="dismiss" swipe:swipeBackView="@+id/back" swipe:swipeCloseAllItemsWhenMoveList="true" swipe:swipeFrontView="@+id/front" swipe:swipeMode="both" /> 

Did anything happen that I missed? Thanks

Answer 1

Just make sure that the layout you inflate in your adapter contains the @+id/back and @+id/front components.

In other words, if your SwipeListView declaration declares @+id/back and @+id/front as scroll views ...

  <...SwipeListView android:id="@+id/swipe_list" android:layout_width="match_parent" android:layout_weight="1.0" android:layout_height="0dp" app:swipeFrontView="@+id/front" <===== app:swipeBackView="@+id/back" <===== app:swipeActionLeft="dismiss" app:swipeCloseAllItemsWhenMoveList="true" app:swipeMode="both" /> 

... then it is expected that the layout you inflate in your adapter contains these components. In the example, the layout inflated in the adapter is called package_row.xml, there is a compressed adapter here:

 @Override public View getView(final int position, View convertView, ViewGroup parent) { final PackageItem item = getItem(position); ViewHolder holder; if (convertView == null) { LayoutInflater li = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE); convertView = li.inflate(R.layout.package_row, parent, false); ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ holder = new ViewHolder(); holder.ivImage = (ImageView) convertView.findViewById(R.id.example_row_iv_image); ... } else { holder = (ViewHolder) convertView.getTag(); } ...