So I am trying to show a certien depending on what item is selected in the spinner. But when i remove a view from the original layout replace it then try to reference it in any way it gives me a null object reference.
Code:
if(subjectSpinner.getSelectedItem().toString().equals("All")){
allSelected();
} else {
if(taskList == null){
Log.i("SQL", "task list id null");
taskList = (RecyclerView) findViewById(R.id.tasks_list);
}
//error points at this line
if(taskList.getParent() == null){
TextView textView = (TextView) findViewById(R.id.textView10);
baseView.removeAllViews();
baseView.addView(appBarLayout);
baseView.addView(subjectSpinner);
baseView.addView(taskList);
baseView.addView(textView);
}
The allSelected() method:
void allSelected (){
subjectSpinner = (Spinner) findViewById(R.id.tasks_list_spinner);
taskList = (RecyclerView) findViewById(R.id.tasks_list);
baseView = (RelativeLayout) findViewById(R.id.activity_view_tasks);
baseView.removeView(taskList);
ScrollView scrollView = new ScrollView(getApplicationContext());
LinearLayout linearLayout = new LinearLayout(getApplicationContext());
List <TextView> subjectText = new ArrayList <>();
List <RecyclerView> recyclerViews = new ArrayList <>();
List <CustomAdaptor> adaptor = new ArrayList <>();
RelativeLayout.LayoutParams scrollViewParams =
new RelativeLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,
ViewGroup.LayoutParams.MATCH_PARENT);
scrollViewParams.addRule(RelativeLayout.BELOW, R.id.textView10);
RelativeLayout.LayoutParams linearLayoutParams =
new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.MATCH_PARENT,
RelativeLayout.LayoutParams.WRAP_CONTENT);
PS. these are not the full code but I am doing nothing else with the taskList recyclerView outside of these snippets.
Logcat:
Process: com.example.user.timetable_test, PID: 12685
java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.ViewParent android.support.v7.widget.RecyclerView.getParent()' on a null object reference
at com.example.user.timetable_test.ViewTasks$1.onItemSelected(ViewTasks.java:225)
at android.widget.AdapterView.fireOnSelected(AdapterView.java:1165)
at android.widget.AdapterView.dispatchOnItemSelected(AdapterView.java:1154)
at android.widget.AdapterView.access$300(AdapterView.java:59)
at android.widget.AdapterView$SelectionNotifier.run(AdapterView.java:1121)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:158)
at android.app.ActivityThread.main(ActivityThread.java:7225)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120)
The .xml file
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/activity_view_tasks"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.user.timetable_test.ViewTasks"
android:fitsSystemWindows="true">
<android.support.design.widget.AppBarLayout
android:id="@+id/appbar_viewTasks"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:paddingTop="@dimen/appbar_padding_top"
android:theme="@style/AppTheme.AppBarOverlay">
<android.support.v7.widget.Toolbar
android:id="@+id/toolbar3"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary"
app:layout_scrollFlags="scroll|enterAlways"
app:popupTheme="@style/AppTheme.PopupOverlay" android:layout_weight="1"/>
</android.support.design.widget.AppBarLayout>
<Spinner
android:layout_width="200dp"
android:layout_height="wrap_content" android:id="@+id/tasks_list_spinner"
android:layout_below="@+id/appbar_viewTasks" android:layout_alignParentEnd="true"
android:layout_marginEnd="@dimen/activity_vertical_margin"
android:layout_marginTop="@dimen/activity_horizontal_margin"/>
<TextView
android:text="@string/subject"
android:layout_width="wrap_content"
android:layout_height="wrap_content" android:id="@+id/textView10"
android:textAppearance="@style/TextAppearance.AppCompat.Headline"
android:layout_below="@+id/appbar_viewTasks" android:layout_alignParentStart="true"
android:layout_marginStart="@dimen/activity_vertical_margin"
android:layout_marginTop="@dimen/activity_horizontal_margin"/>
<android.support.v7.widget.RecyclerView
android:layout_width="match_parent"
android:layout_height="match_parent" android:id="@+id/tasks_list"
android:fitsSystemWindows="true" android:layout_alignParentBottom="true"
android:layout_alignParentStart="true"
android:layout_marginStart="@dimen/activity_vertical_margin"
android:layout_marginEnd="@dimen/activity_vertical_margin"
android:layout_below="@+id/textView10"
android:layout_marginBottom="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"/>
</RelativeLayout>
So does someone know why am I getting this error and how to fix it?
BTW this is not a duplicate of What is a NullPointerException, and how do I fix it?. Yes it is about null pointer exception, but it doesn't ask what is a null pointer exception, but rather how did I get a null pointer exception in this code?
Since I am editing the question and can't post an answer, let me say that I fixed the error by not removing the views, instead making them invisible. It is a work around and not really a fix. If you have a similar problem, hope this helps :)
