我正在编程一个Android应用。一些用户得到一个 NullPointerException 但我找不到原因（在我的手机和6个不同的AVD上，它可以工作，但我不能重现这个异常，所以我可以在我的Android Studio中看看这个错误并在那里玩）。
PlayConsole为我的用户显示了这个错误日志。我的知识太少，无法从这个日志中得到原因。谁能看出原因？
错误日志。
java.lang.NullPointerException:
at de.schwembo.beercount.AuswertungFragment.onCreateView (AuswertungFragment.java:85)
at androidx.fragment.app.Fragment.performCreateView (Fragment.java:2600)
at androidx.fragment.app.FragmentManagerImpl.moveToState (FragmentManagerImpl.java:881)
at androidx.fragment.app.FragmentManagerImpl.moveFragmentToExpectedState (FragmentManagerImpl.java:1238)
at androidx.fragment.app.FragmentManagerImpl.moveToState (FragmentManagerImpl.java:1303)
at androidx.fragment.app.BackStackRecord.executeOps (BackStackRecord.java:439)
at androidx.fragment.app.FragmentManagerImpl.executeOps (FragmentManagerImpl.java:2079)
at androidx.fragment.app.FragmentManagerImpl.executeOpsTogether (FragmentManagerImpl.java:1869)
at androidx.fragment.app.FragmentManagerImpl.removeRedundantOperationsAndExecute (FragmentManagerImpl.java:1824)
at androidx.fragment.app.FragmentManagerImpl.execSingleAction (FragmentManagerImpl.java:1696)
at androidx.fragment.app.BackStackRecord.commitNowAllowingStateLoss (BackStackRecord.java:299)
at androidx.fragment.app.FragmentPagerAdapter.finishUpdate (FragmentPagerAdapter.java:235)
at androidx.viewpager.widget.ViewPager.populate (ViewPager.java:1244)
at androidx.viewpager.widget.ViewPager.populate (ViewPager.java:1092)
at androidx.viewpager.widget.ViewPager.onMeasure (ViewPager.java:1622)
at android.view.View.measure (View.java:22286)
at android.view.ViewGroup.measureChildWithMargins (ViewGroup.java:6668)
at androidx.coordinatorlayout.widget.CoordinatorLayout.onMeasureChild (CoordinatorLayout.java:760)
at com.google.android.material.appbar.HeaderScrollingViewBehavior.onMeasureChild (HeaderScrollingViewBehavior.java:99)
at com.google.android.material.appbar.AppBarLayout$ScrollingViewBehavior.onMeasureChild (AppBarLayout.java:1892)
at androidx.coordinatorlayout.widget.CoordinatorLayout.onMeasure (CoordinatorLayout.java:831)
at android.view.View.measure (View.java:22286)
at android.view.ViewGroup.measureChildWithMargins (ViewGroup.java:6668)
at android.widget.FrameLayout.onMeasure (FrameLayout.java:185)
at androidx.appcompat.widget.ContentFrameLayout.onMeasure (ContentFrameLayout.java:143)
at android.view.View.measure (View.java:22286)
at android.view.ViewGroup.measureChildWithMargins (ViewGroup.java:6668)
at android.widget.LinearLayout.measureChildBeforeLayout (LinearLayout.java:1539)
at android.widget.LinearLayout.measureVertical (LinearLayout.java:823)
at android.widget.LinearLayout.onMeasure (LinearLayout.java:702)
at android.view.View.measure (View.java:22286)
at android.view.ViewGroup.measureChildWithMargins (ViewGroup.java:6668)
at android.widget.FrameLayout.onMeasure (FrameLayout.java:185)
at android.view.View.measure (View.java:22286)
at android.view.ViewGroup.measureChildWithMargins (ViewGroup.java:6668)
at android.widget.LinearLayout.measureChildBeforeLayout (LinearLayout.java:1539)
at android.widget.LinearLayout.measureVertical (LinearLayout.java:823)
at android.widget.LinearLayout.onMeasure (LinearLayout.java:702)
at android.view.View.measure (View.java:22286)
at android.view.ViewGroup.measureChildWithMargins (ViewGroup.java:6668)
at android.widget.FrameLayout.onMeasure (FrameLayout.java:185)
at com.android.internal.policy.DecorView.onMeasure (DecorView.java:837)
at android.view.View.measure (View.java:22286)
at android.view.ViewRootImpl.performMeasure (ViewRootImpl.java:2646)
at android.view.ViewRootImpl.measureHierarchy (ViewRootImpl.java:1674)
at android.view.ViewRootImpl.performTraversals (ViewRootImpl.java:1933)
at android.view.ViewRootImpl.doTraversal (ViewRootImpl.java:1558)
at android.view.ViewRootImpl$TraversalRunnable.run (ViewRootImpl.java:7463)
at android.view.Choreographer$CallbackRecord.run (Choreographer.java:1041)
at android.view.Choreographer.doCallbacks (Choreographer.java:847)
at android.view.Choreographer.doFrame (Choreographer.java:774)
at android.view.Choreographer$FrameDisplayEventReceiver.run (Choreographer.java:1027)
at android.os.Handler.handleCallback (Handler.java:809)
at android.os.Handler.dispatchMessage (Handler.java:102)
at android.os.Looper.loop (Looper.java:166)
at android.app.ActivityThread.main (ActivityThread.java:7555)
at java.lang.reflect.Method.invoke (Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run (RuntimeInit.java:469)
at com.android.internal.os.ZygoteInit.main (ZygoteInit.java:963)
受影响的函数(AuswertungFragment.java:85)是这样的，它是在... onCreateView() 方法中初始化。
// Spinner for Months differentiation
spinnerMonat.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
@Override
public void onItemSelected(AdapterView<?> parentView, View selectedItemView, int position, long id) {
// IF statement for year/gesamt selection
if (spinnerMonat.getSelectedItem().toString().equals(getString(R.string.gesamt))) {
for (int i = 0; i < 12; i++) {
alleDatenAusCursor = dataSource.zaehleAllesZuCursor(dataSource.getCursorFuerMonat(i + 1));
anzahlZuMonate[i] = String.valueOf(alleDatenAusCursor[0]);
preisZuMonate[i] = String.valueOf(alleDatenAusCursor[1]);
mengeZuMonate[i] = String.valueOf(alleDatenAusCursor[2]);
}
fuelleLV4(monate, anzahlZuMonate, preisZuMonate, mengeZuMonate);
} else {
for (int i = 0; i < 12; i++) {
alleDatenAusCursor = dataSource.zaehleAllesZuCursor(dataSource.getCursorFuerMonatJahr(spinnerMonat.getSelectedItem().toString(), i + 1));
anzahlZuMonate[i] = String.valueOf(alleDatenAusCursor[0]);
preisZuMonate[i] = String.valueOf(alleDatenAusCursor[1]);
mengeZuMonate[i] = String.valueOf(alleDatenAusCursor[2]);
}
fuelleLV4(monate, anzahlZuMonate, preisZuMonate, mengeZuMonate);
}
}
@Override
public void onNothingSelected(AdapterView<?> parentView) {
for (int i = 0; i < 12; i++) {
alleDatenAusCursor = dataSource.zaehleAllesZuCursor(dataSource.getCursorFuerMonat(i + 1));
anzahlZuMonate[i] = String.valueOf(alleDatenAusCursor[0]);
preisZuMonate[i] = String.valueOf(alleDatenAusCursor[1]);
mengeZuMonate[i] = String.valueOf(alleDatenAusCursor[2]);
}
fuelleLV4(monate, anzahlZuMonate, preisZuMonate, mengeZuMonate);
}
});
dataSource被初始化在 onCreate() 这样的方法。
dataSource = new DatabaseHandler(getActivity());
Spinner的初始化是这样的 onCreateView() 方法是这样的。
final Spinner spinnerMonat = rootView.findViewById(R.id.spinnerMonth2);
问题是我有一个替代的Layout，不包括spinner的