I have a boolean method in a class made in Java for Android, however, the return of the array variable that I am using marks an error every time I use it in the activity where I want it to be.
This is my method: (The class is called Querys)
public String[] getAlumnos(Context context, String usuario) {
String[] alumnos = new String[50];
return alumnos;
}
This is the code of my activity where I am trying to get the value of said method and assign it to a new array:
Querys q = new Querys();
String[] alumnos = q.getAlumnos(this, usuario); // <--- Aquí es el problema
q.getAlumnos(this, usuario); // <--- Pues si lo uso sin asignarle el valor que retorna a ninguna variable, hace todo el trabajo perfectamente bien.
This is the only thing I've been able to get as a "bug" if you can call it that.
2020-08-21 22:27:53.970 9073-9073/com.example.apk E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.apk, PID: 9073
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:453)
at android.widget.ArrayAdapter.getView(ArrayAdapter.java:415)
at android.widget.Spinner.measureContentWidth(Spinner.java:856)
at android.widget.Spinner.onMeasure(Spinner.java:606)
at androidx.appcompat.widget.AppCompatSpinner.onMeasure(AppCompatSpinner.java:428)
at android.view.View.measure(View.java:23196)
at androidx.constraintlayout.widget.ConstraintLayout.internalMeasureChildren(ConstraintLayout.java:1227)
at androidx.constraintlayout.widget.ConstraintLayout.onMeasure(ConstraintLayout.java:1572)
at android.view.View.measure(View.java:23196)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6753)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
at androidx.appcompat.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:143)
at android.view.View.measure(View.java:23196)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6753)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1535)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:825)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:704)
at android.view.View.measure(View.java:23196)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6753)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
at android.view.View.measure(View.java:23196)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6753)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1535)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:825)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:704)
at android.view.View.measure(View.java:23196)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6753)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
at com.android.internal.policy.DecorView.onMeasure(DecorView.java:720)
at android.view.View.measure(View.java:23196)
at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2802)
at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1647)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1930)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1535)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:7405)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:1044)
at android.view.Choreographer.doCallbacks(Choreographer.java:839)
at android.view.Choreographer.doFrame(Choreographer.java:774)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:1030)
at android.os.Handler.handleCallback(Handler.java:873)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:201)
at android.app.ActivityThread.main(ActivityThread.java:6864)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:547)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:873)