So I'm using PagerSlidingTabStrip. I implemented it just like it was suggested in the tutorial and followed the sample/demo-app code.
I have 3 tabs: Calculator | Percentage | History
All 3 extend Fragment. I can swipe between these tabs no problem. But I get a NullPointerException is when I'm on the Calculator tab trying to click the History tab. Here's the error I'm getting:
java.lang.NullPointerException
at sleeping_vityaz.onerm.tabsswipe.HistoryFragment.loadScreen(HistoryFragment.java:69)
at sleeping_vityaz.onerm.tabsswipe.HistoryFragment.setUserVisibleHint(HistoryFragment.java:57)
at android.support.v4.app.FragmentPagerAdapter.setPrimaryItem(FragmentPagerAdapter.java:130)
at android.support.v4.view.ViewPager.populate(ViewPager.java:1071)
at android.support.v4.view.ViewPager.setCurrentItemInternal(ViewPager.java:555)
at android.support.v4.view.ViewPager.setCurrentItemInternal(ViewPager.java:514)
at android.support.v4.view.ViewPager.setCurrentItem(ViewPager.java:495)
at com.astuetz.PagerSlidingTabStrip$2.onClick(PagerSlidingTabStrip.java:299)
at android.view.View.performClick(View.java:4438)
at android.view.View$PerformClick.run(View.java:18422)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5001)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)
Here is my HistoryFragment code:
public class HistoryFragment extends Fragment {
public RecordArrayAdapter adapter;
ArraySwipeAdapterSample mAdapter;
View rootView;
DBTools dbTools = null;
@Override
public View onCreateView(LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
rootView = inflater.inflate(R.layout.history_layout, container, false);
loadScreen();
return rootView;
}
@Override
public void setUserVisibleHint(boolean isVisibleToUser) {
super.setUserVisibleHint(isVisibleToUser);
if (isVisibleToUser) {
loadScreen();
} else {
Log.d("MyFragment", "Fragment is not visible.");
}
}
private void loadScreen() {
dbTools = DBTools.getInstance(this.getActivity());
final List<RecordObject> recordsList = dbTools.getAllRecords();
if (recordsList.size() != 0) {
ListView listView = (ListView) rootView.findViewById(R.id.records_list);
mAdapter = new ArraySwipeAdapterSample<String>(getActivity(), R.layout.record_entry, R.id.key_id, recordsList);
listView.setAdapter(mAdapter);
mAdapter.setMode(SwipeItemMangerImpl.Mode.Single);
SwipeLayout swipeLayout = (SwipeLayout) getActivity().findViewById(R.id.swipe);
/*adapter = new RecordArrayAdapter(this.getActivity(), recordsList);
listView.setAdapter(adapter);*/
}
}
}
history_layout.xml
<ListView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/records_list"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="1"></ListView>
record_entry.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="80dp">
<com.daimajia.swipe.SwipeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/swipe"
android:layout_width="match_parent"
android:layout_height="80dp">
<!-- Bottom View Start-->
<LinearLayout
android:id="@+id/bottom_wrapper"
android:layout_width="80dp"
android:layout_height="match_parent"
android:background="#66ddff00"
android:weightSum="1">
<ImageView
android:id="@+id/img_trash"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@color/accent"
android:paddingLeft="25dp"
android:paddingRight="25dp"
android:src="@drawable/ic_action_delete" />
<!--What you want to show-->
</LinearLayout>
<!-- Bottom View End-->
<!-- Surface View Start -->
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#ffffff"
android:padding="10dp">
<!--What you want to show in SurfaceView-->
<TextView
android:id="@+id/key_id"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:visibility="gone" />
<TextView
android:id="@+id/onerm"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_weight="2.2"
android:gravity="center_vertical"
android:text="WEIGHT"
android:textColor="#444444"
android:textSize="16sp"
android:layout_marginLeft="4dp" />
<TableLayout
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_gravity="center_vertical"
android:layout_weight="3">
<TextView
android:id="@+id/weight"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="WEIGHT"
android:textColor="#444444"
android:textSize="12sp" />
<TextView
android:id="@+id/reps"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="REPS"
android:textColor="#444444"
android:textSize="12sp" />
</TableLayout>
<TextView
android:id="@+id/date"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_gravity="center_vertical|right"
android:layout_weight="2"
android:text="DATE"
android:textColor="#444444"
android:textSize="12sp"
android:gravity="center_vertical|right" />
</LinearLayout>
<!-- Surface View End -->
</com.daimajia.swipe.SwipeLayout>
</LinearLayout>
TabsAdapter.java
public class TabsAdapter extends FragmentPagerAdapter {
final private int NUM_TABS = 3;
public TabsAdapter(FragmentManager fm) {
super(fm);
}
@Override
public Fragment getItem(int position) {
switch (position) {
case 0: return new CalculatorFragment();
case 1: return new PercentageFragment();
case 2: return new HistoryFragment();
}
return null;
}
@Override
public int getCount() {
return NUM_TABS;
}
@Override
public CharSequence getPageTitle (int position) {
switch (position) {
case 0: return "Calculator";
case 1: return "Percentage";
case 2: return "History";
default:return null;
}
}
}
What could be causing this error? This only happens when I try to switch from the Calculator fragment to History fragment by clicking the tabs (and not swiping) AND when the user has already saved something to the database (recordsList.size() != 0). If recordsList is empty, there's no error.
Also, HistoryFragment.java:68 is the following line
ListView listView = (ListView) rootView.findViewById(R.id.records_list);
I was able to solve this by myself :) So what happened was that setUserVisibleHint method was calling loadScreen because the screen was visible to the user. The problem with that was that History fragment's onCreateView was never called in the first place! So all I had to do was to check for rootView!=null in my loadScreen method. Duh! This fixed everything.
This is what I had before
if (recordsList.size() != 0) {
and what I have now
if (recordsList.size() != 0 && rootView!=null) {