NullPointException in Fragment with CheckBox

Question

In my aplication i have a fragment were i have any checkbox. When i chek start a TextToSpech. I have created a similar version without fragment and it work fine. But when i implemented it in a fragment it doesn't works. Her is my code:

public class OneFragment extends Fragment implements TextToSpeech.OnInitListener, CompoundButton.OnCheckedChangeListener {
private TextToSpeech tts;

ListView listView;
ArrayAdapter<Model> adapter;
List<Model> list = new ArrayList<Model>();

public OneFragment() {
}

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {

    View returnView = inflater.inflate(R.layout.fragment_one, container, false);
    listView = (ListView) returnView.findViewById(R.id.listView);
    adapter = new MyAdapter(getActivity(), getModel());
    listView.setAdapter(adapter);
    final CheckBox chk = (CheckBox)returnView.findViewById(R.id.checkBox);
    chk.setOnCheckedChangeListener(OneFragment.this);

    return returnView;
}

@Override
public void setUserVisibleHint(boolean isVisibleToUser) {
    super.setUserVisibleHint(isVisibleToUser);
    if (isVisibleToUser) {
        tts = new TextToSpeech(getActivity(), this);
    }
}

private List<Model> getModel() {
    list.add(new Model("Linux", "S"));
    list.add(new Model("Linux", "S"));
    list.add(new Model("Linux", "S"));
    list.add(new Model("Linux", "S"));
    list.add(new Model("Linux", "S"));

    return list;
}

@Override
public void onInit(int status) {
    if (status == TextToSpeech.SUCCESS) {

        int result = tts.setLanguage(Locale.ITALIAN);

        if (result == TextToSpeech.LANG_MISSING_DATA
                || result == TextToSpeech.LANG_NOT_SUPPORTED) {
            Log.e("TTS", "This Language is not supported");
        } else {

            startSpeak();
        }

    } else {
        Log.e("TTS", "Initilization Failed!");
    }
}

private void startSpeak() {
    tts.speak("Ciao", TextToSpeech.QUEUE_FLUSH, null);
}

@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
    CheckBox chk = (CheckBox)getActivity().findViewById(R.id.checkBox);
      for (Model i: list ) {
        if (chk.isChecked()) {
            this.startSpeak();
        }
    }
}
}

This is the partial LogCat result:

java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.CheckBox.setOnCheckedChangeListener(android.widget.CompoundButton$OnCheckedChangeListener)' on a null object reference

How should i do?

I know what a null point exception is. But i don't understend because i have this problem when i use fragment. I have build a similar app that works. Now i would create the same app whit fragment (For swipe whit ViewPager) but i haved any problems, some i have fixed it other not. So why i have NullPointException when use fragment? — Marco ShepMonkey De Rossi, Nov 23 '15 at 16:22

score 3 · Answer 1 · answered Nov 23 '15 at 15:52

3

i have a fragment were i have any checkbox

If CheckBox is inside Fragment layout in R.layout.fragment_one then use OneFragment.this.getView() to access CheckBox from layout instead of getActivity() :

CheckBox chk = (CheckBox)OneFragment.this.getView().findViewById(R.id.checkBox);

Or declare CheckBox chk as class level variable and initialize it inside onCreateView :

...
chk = (CheckBox)returnView.findViewById(R.id.checkBox);
...

answered Nov 23 '15 at 15:52

ρяσѕρєя K

132,198
53
198
213

No this is not the problem. I have the problem at the setOnCheckedChangeListener. – Marco ShepMonkey De Rossi Nov 23 '15 at 16:14
1

@MarcoShepMonkeyDeRossi: what problem with `setOnCheckedChangeListener` ? it is very clear you are using `getActivity()` for accessing CheckBox from `R.layout.fragment_one` – ρяσѕρєя K Nov 23 '15 at 16:16
@MarcoShepMonkeyDeRossi: have you tried to change code according to my answer? – ρяσѕρєя K Nov 23 '15 at 16:17
I have the NullPointException at this code: chk.setOnCheckedChangeListener(OneFragment.this); And not at this code: chk = (CheckBox)returnView.findViewById(R.id.checkBox); – Marco ShepMonkey De Rossi Nov 23 '15 at 16:24
@MarcoShepMonkeyDeRossi: Please show updated code – ρяσѕρєя K Nov 23 '15 at 16:25
Don't have updated the code – Marco ShepMonkey De Rossi Nov 23 '15 at 16:32
@MarcoShepMonkeyDeRossi: then change your code according to my answer. if issue not get resolved then show me updated code – ρяσѕρєя K Nov 23 '15 at 16:33
I have do it, and with your code have the null point exception at the code that you have give me. With my code haven't this problem. My problem is in the setOnCheckedChangeListener. Here have an NullPointException. Look my LogCat please – Marco ShepMonkey De Rossi Nov 23 '15 at 16:38
@MarcoShepMonkeyDeRossi: `checkBox ` CheckBox is not inside `R.layout.fragment_one` layout? in which layout you have ? – ρяσѕρєя K Nov 23 '15 at 16:40
Yes it is. If i don't call the setOnCheckedChangeListener the app work. When i have implemtented this method it does not work – Marco ShepMonkey De Rossi Nov 23 '15 at 16:41
@MarcoShepMonkeyDeRossi: In which layout you have CheckBox with `checkbox` id? – ρяσѕρєя K Nov 23 '15 at 16:43
Sorry, my mistake. I have forget the i have the CheckBox in row.xml that define the item for the listView that is in fragment_one.xml Sorry – Marco ShepMonkey De Rossi Nov 23 '15 at 16:48
@MarcoShepMonkeyDeRossi: then set `setOnCheckedChangeListener ` for CheckBox in `getView` method of `MyAdapter ` Adapter. let me know if any help required.Thanks – ρяσѕρєя K Nov 23 '15 at 17:06
1

It works, thanks and sorry for my mistake. – Marco ShepMonkey De Rossi Nov 23 '15 at 17:22
@MarcoShepMonkeyDeRossi: Great if it's working – ρяσѕρєя K Nov 23 '15 at 17:26

score 0 · Answer 2 · answered Nov 23 '15 at 16:21

0

try this in your onCheckedChanged method.

switch (buttonView.getId())
case R.id.checkBox:
/*
Do something
*/
break;

answered Nov 23 '15 at 16:21

brayan camilo villate leon

271
2
5

Nope, this don't work. I have a nullPointException at this code: chk.setOnCheckedChangeListener(OneFragment.this) – Marco ShepMonkey De Rossi Nov 23 '15 at 16:33
in your R.layout.fragment_one you set the id checkBox ? to object ? try change the name of id – brayan camilo villate leon Nov 23 '15 at 16:42
I have the CheckBox in row.xml that define the item for the listView that is in fragment_one.xml – Marco ShepMonkey De Rossi Nov 23 '15 at 16:48
when you declare View returnView = inflater.inflate(R.layout.fragment_one, container, false); the returnview contains all id's declare in this view, so if you declare the check box in row.xml you dont try this this returnView.findViewById(R.id.checkBox); because checkbox dont exist – brayan camilo villate leon Nov 23 '15 at 16:52
So, what should i do? – Marco ShepMonkey De Rossi Nov 23 '15 at 17:04
create on use your checkbox in your adapter MyAdapter no in yoour fragment – brayan camilo villate leon Nov 23 '15 at 17:07
I have resolved thanks. – Marco ShepMonkey De Rossi Nov 23 '15 at 17:23

NullPointException in Fragment with CheckBox

2 Answers2