I have a following problem. I have a ListView which displays a test. In each ListView row there is a question and a RadioGroup with answers. THe problem I am experiencing is that I am getting this error everytime when I scroll the ListView down and I don't know the cause of such behaviour:
LogCat:
02-05 11:22:56.712 27296-27296/com.fragon.testjson E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.fragon.testjson, PID: 27296
java.lang.NullPointerException
at com.fragon.testjson.ListAdapter.getView(ListAdapter.java:38)
at android.widget.AbsListView.obtainView(AbsListView.java:2255)
at android.widget.ListView.makeAndAddView(ListView.java:1790)
at android.widget.ListView.fillDown(ListView.java:691)
at android.widget.ListView.fillGap(ListView.java:655)
at android.widget.AbsListView.trackMotionScroll(AbsListView.java:5143)
at android.widget.AbsListView.scrollIfNeeded(AbsListView.java:3243)
at android.widget.AbsListView.onTouchMove(AbsListView.java:3587)
at android.widget.AbsListView.onTouchEvent(AbsListView.java:3431)
at android.view.View.dispatchTouchEvent(View.java:7837)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2210)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1945)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2216)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1959)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2216)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1959)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2216)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1959)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2216)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1959)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2216)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1959)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2216)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1959)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2216)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1959)
at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:2075)
at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1522)
at android.app.Activity.dispatchTouchEvent(Activity.java:2458)
at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:2023)
at android.view.View.dispatchPointerEvent(View.java:8017)
at android.view.ViewRootImpl$ViewPostImeInputStage.processPointerEvent(ViewRootImpl.java:3966)
at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:3845)
at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3405)
at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3455)
at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3424)
at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:3531)
at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3432)
at android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:3588)
at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3405)
at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3455)
at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3424)
at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3432)
at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3405)
at android.view.ViewRootImpl.deliverInputEvent(ViewRootImpl.java:5554)
at android.view.ViewRootImpl.doProcessInputEvents(ViewRootImpl.java:5534)
at android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:5505)
at android.view.ViewRootImpl$WindowInputEventReceiver.onInputEvent(ViewRootImpl.java:5634)
at android.view.InputEventReceiver.dispatchInputEvent(InputEventReceiver.java:185)
at android.view.InputEventReceiver.nativeConsumeBatchedInputEvents(Native Method)
at android.view.InputEventReceiver.consumeBatchedInputEvents(InputEventReceiver.java:176)
at android.view.ViewRootImpl.doConsumeBatchedInput(ViewRootImpl.java:5607)
at android.view.ViewRootImpl$ConsumeBatchedInputRunnable.run(ViewRootImpl.java:5653)
at andr
My ListAdapter:
public class ListAdapter extends ArrayAdapter<Question> {
public ListAdapter(Context context, ArrayList<Question> questions) {
super(context, R.layout.list_item, questions);
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
if (convertView == null) {
convertView = LayoutInflater.from(getContext()).inflate(R.layout.list_item, parent, false);
}
final Question question = getItem(position);
TextView id = (TextView) convertView.findViewById(R.id.question_id);
TextView text = (TextView) convertView.findViewById(R.id.question_text);
id.setText(Integer.toString(question.getId()));
text.setText(question.getName());
RadioGroup rg = (RadioGroup) convertView.findViewById(R.id.question);
rg.removeAllViews();//Line 38. Whithout his line I also get the same error.
rg.setId(position);
int i = 0;
for (String qA : question.answers) {
RadioButton rb = new RadioButton(getContext());
rb.setText(qA.toString());
rg.addView(rb);
rb.setId(i);
i++;
}
rg.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(RadioGroup group, int checkedId) {
question.setUserAnswer(checkedId);
Log.d("User answer", Integer.toString(checkedId));
}
});
return convertView;
}
}
The line rg.setId(position); is changing the RadioGroup's ID to something other than R.id.question, so when then View gets recycled - i.e., when you scroll - findViewById(R.id.question) is returning null.
If you need to cache the position, you could use the setTag() and getTag() methods instead. You could also just cache the Question object instead. For example:
//rg.setId(position);
rg.setTag(question);
...
rg.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(RadioGroup group, int checkedId)
{
Question q = (Question) group.getTag();
q.setUserAnswer(checkedId);
Log.d("User answer", Integer.toString(checkedId));
}
});
You could also define just one RadioGroup.OnCheckedChangeListener instead of creating a new one for each group.
//rg.setId(position);
rg.setTag(question);
...
rg.setOnCheckedChangeListener(checkListener);
...
...
private RadioGroup.OnCheckedChangeListener checkListener =
new RadioGroup.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(RadioGroup group, int checkedId)
{
Question q = (Question) group.getTag();
q.setUserAnswer(checkedId);
Log.d("User answer", Integer.toString(checkedId));
}
};