What can cause NullPointerException when settingAdapter in different versions of Android?

Question

Android

The app crashes on some recent versions of Android, displaying

java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String java.lang.Object.toString()' on a null object reference
            at android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java:394)
            at android.widget.ArrayAdapter.getView(ArrayAdapter.java:362)
            at android.widget.AbsListView.obtainView(AbsListView.java:2347)
            at android.widget.ListView.measureHeightOfChildren(ListView.java:1270)
            at android.widget.ListView.onMeasure(ListView.java:1182)
            at android.view.View.measure(View.java:17547)
            at android.widget.RelativeLayout.measureChild(RelativeLayout.java:697)
            at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:481)
            at android.view.View.measure(View.java:17547)
            at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5535)
            at android.widget.FrameLayout.onMeasure(FrameLayout.java:436)
            at android.support.v7.internal.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:124)
            at android.view.View.measure(View.java:17547)
            at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5535)
            at android.support.v7.internal.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:444)
            at android.view.View.measure(View.java:17547)
            at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5535)
            at android.widget.FrameLayout.onMeasure(FrameLayout.java:436)
            at android.view.View.measure(View.java:17547)
            at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5535)
            at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1436)
            at android.widget.LinearLayout.measureVertical(LinearLayout.java:722)
            at android.widget.LinearLayout.onMeasure(LinearLayout.java:613)
            at android.view.View.measure(View.java:17547)
            at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5535)
            at android.widget.FrameLayout.onMeasure(FrameLayout.java:436)
            at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2615)
            at android.view.View.measure(View.java:17547)
            at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2015)
            at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1173)
            at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1379)
            at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1061)
            at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5885)
            at android.view.Choreographer$CallbackRecord.run(Choreographer.java:767)
            at android.view.Choreographer.doCallbacks(Choreographer.java:580)
            at android.view.Choreographer.doFrame(Choreographer.java:550)
            at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:753)
            at android.os.Handler.handleCallback(Handler.java:739)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5254)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)

The function that throws the exception:

private void loadEvents(){
        ArrayAdapter<String> adap = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, enames);
        ListView event_list = (ListView) findViewById(R.id.eventslist);
        event_list.setAdapter(adap);
        event_list.setOnItemClickListener(new OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                event = eids[position];
                eType = etypes[position];
                group();
            }
        });
    }

If you comment out the line "event_list.setAdapter(adap);" the application does not crash, and if left, it crashes at the very end of the loadEvents() function; The data in adap is correct, and the ListView is present in the current ContentView.
In versions from 4.0 to 4.4.1 the application works fine.

Answer 1

Check names. What is this variable?
UPD: I explain for the stubborn and secretive:
What is going on with you?
In the ArrayAdapter.createViewFromResource() method, the toString() method is called on a null object.
Specifically at this location:

List<T> mObjects;
...
T item = getItem(position);
if (item instanceof CharSequence) {
    text.setText((CharSequence)item);
} else {
    text.setText(item.toString());
}

Where T is String.
Accordingly, if item == null, then (null instanceof CharSequence) gives false and you have a NullPointer.
Is that clearer? Watch what you are passing to the ArrayAdapter constructor.

Answer 2

show the adapter's getView