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POandroid viewpager adapter and NullPointerException
 

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  1. POandroid viewpager adapter and NullPointerException
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    <p>Sometimes I'm getting NullPointerExceptions in google play reports, where (as I think) I use viewpager or it's adapter. This is my code:</p> <pre><code>private PagerAdapter mPagerAdapter; private ViewPager mPagerView; private static class PagerAdapter extends FragmentStatePagerAdapter { HashMap&lt;Integer, PageFragment&gt; mPageReferenceMap; public PagerAdapter(FragmentManager fm) { super(fm); mPageReferenceMap = new HashMap&lt;Integer, PageFragment&gt;(); } @Override public int getCount() { return NUM_ITEMS; } @Override public Fragment getItem(int position) { PageFragment fragment = PageFragment.newInstance(position); mPageReferenceMap.put(position, fragment); return fragment; } @Override public void destroyItem(ViewGroup container, int position, Object object) { super.destroyItem(container, position, object); mPageReferenceMap.remove(position); } public PageFragment getFragment(int key) { return mPageReferenceMap.get(key); } @Override public int getItemPosition(Object object) { return POSITION_NONE; } } </code></pre> <p>in onCreate():</p> <pre><code> mPagerAdapter = new PagerAdapter(getSupportFragmentManager()); mPagerView = (ViewPager) findViewById(R.id.pager); </code></pre> <p>Then, at this line I'm getting crash reports from some users:</p> <pre><code> mPagerAdapter.getFragment(mPagerView.getCurrentItem()).whatEverFunctionFromFragment(); </code></pre> <p>I call fragments this way in different places (independent of each other) - in onDismiss function of the dialog, in onItemClick of ListPopupWindow, etc - with different functions in fragment.</p> <p><strong>More info:</strong> I've got this error after I have done everything that sad <a href="https://stackoverflow.com/questions/13897294/android-viewpager-adapter-and-nullpointerexception#comment19255183_13897294">Heinrisch</a>. This error appears when user resumes to the activity. But I still don't understand how to fix it and why is it happening? Should I save <code>mPageReferenceMap</code> in onSaveInstanceState()? or in onStop()? What am I missing in lifecycle of Activity and Fragments?</p>
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    1. COYou should provide more details, like from where(and when) do you call that line. Also, it there a specific Android version on which this happens?
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    2. COFragments are added since API 11. Do you target the correct API in the market?
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    3. COLuksprog: I will add more details today. Mohamed: as you can see I'm using SupportFragmentManager.
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