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PONull pointer exception when creating another fragments
 

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  1. PONull pointer exception when creating another fragments
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    <p>Im using viewPager with action bar tabs in my app and every fragment has own fragment xml file for UI but I have two problems. First problem is if I create 3 fragments then when app is laoded first fragment is Ok I swipe to second - second is Ok then I swipe to third and return tu first and first fragment is demaged - has default values(all data are losed but I dont know why) Second biggest problem is when I create third fragment and I want initialize items inside him I get null pointer because(I think third fragment wasnt created or maybe is not good). Null pointer exception on <code>PlaceholderFragment3()</code></p> <p>Here is my code></p> <pre><code>public class SectionsPagerAdapter extends FragmentPagerAdapter { public SectionsPagerAdapter(FragmentManager fm) { super(fm); } @Override public Fragment getItem(int position) { switch (position) { case 0: return new PlaceholderFragment().newInstance(0); case 1: return new PlaceholderFragment2().newInstance(0); case 2: return new PlaceholderFragment3().newInstance(0); } return null; } @Override public int getCount() { return 3; } @Override public CharSequence getPageTitle(int position) { switch (position) { case 0: return getString(R.string.title_section1); case 1: return getString(R.string.title_section2); case 2: return getNameOfDayOfWeek(DAY_AFTER_TOMORROW); } return null; } } public static class PlaceholderFragment extends Fragment { private static final String ARG_SECTION_NUMBER = "section_number"; public static PlaceholderFragment newInstance(int sectionNumber) { PlaceholderFragment fragment = new PlaceholderFragment(); Bundle args = new Bundle(); args.putInt(ARG_SECTION_NUMBER, sectionNumber); fragment.setArguments(args); return fragment; } public PlaceholderFragment() { } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View rootView = inflater.inflate(R.layout.fragment_main, container, false); MainActivity.iMainActivity.dateToday=(TextView) rootView.findViewById(R.id.tvDateOfDay); return rootView; } } </code></pre> <p>ANOTHER FRAGMENTS ARE CREATED LIKE PlaceholderFragment only name is changed to PlaceholderFragment2 and 3</p> <pre><code>public static MainActivity iMainActivity; // instance of MainActivity public class JSONWeatherTaskDay3 extends AsyncTask&lt;String, Void, Weather&gt; { @Override protected Weather doInBackground(String... params) { Weather weatherDay3 = new Weather(); String data = ((new WeatherHttpClient()).getWeatherData(params[0])); try { weatherDay3 = JSONWeatherParser.getWeather(data,2); } catch (JSONException e) { e.printStackTrace(); } return weatherDay3; } @Override protected void onPostExecute(Weather weather) { MainActivity.iMainActivity.cityNameDay3.setText(weather.location.getCity()); } .... </code></pre> <p>}</p> <p>JSONWeatherTaskDay3 is Task for third fragment where I get exception, fragment 1 and 2 have another TASK classes</p> <p>Exception></p> <pre><code>java.lang.NullPointerException at com.pfittech.andweather.MainActivity$JSONWeatherTaskDay3.onPostExecute(MainActivity.java:636) at com.pfittech.andweather.MainActivity$JSONWeatherTaskDay3.onPostExecute(MainActivity.java:618) at android.os.AsyncTask.finish(AsyncTask.java:602) at android.os.AsyncTask.access$600(AsyncTask.java:156) at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:615) at android.os.Handler.dispatchMessage(Handler.java:99) at android.os.Looper.loop(Looper.java:137) at android.app.ActivityThread.main(ActivityThread.java:4448) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:511) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:823) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:590) at dalvik.system.NativeStart.main(Native Method) </code></pre>
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    1. PTQuestion
    1. USPavol Franek
    1. USPavol Franek
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    1. COYou'll have to post your stacktrace and code whre the NPE happened. As to the fragments losing their states, the adapter will destroy fragments that are 'far away' from the curretn fragment and you'll have to come up with an implementation on how to save their state.
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      1. PONull pointer exception when creating another fragments
      1. USasco
    2. COok I add logcat and TASK class where is this exception.
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      1. PONull pointer exception when creating another fragments
      1. USPavol Franek
    3. COWell something in your MainActivity.java:636 is null, I'd fire up the debug perspective and check which object it is, hard to tell from here. Waether could be null, weather.location could be null, cityNameDay3 could be null.
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      1. PONull pointer exception when creating another fragments
      1. USasco
 

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