I'm making an app that displays the same menus for different users, each menu being a fragment, but depending on the user certain things are visible and others aren't.
However, when I try to set a component's visibility as GONE
I get a null pointer exception error, I'm still testing so I'm only using a textView on the fragment xml.
I've already tried initializing both the TextView
and the FragmentMenuEncomenda
, the class of the fragment I'm using, objects, both inside the if clause before the onCreate()
method, and after the setContentView()
, like the tabLayout
and viewPager
.
The if clause was only to make sure the user type was correct and the code in question is as follows:
public class PaginaInicialCliente extends AppCompatActivity {
private SharedPreferences sharedpreferences;
private TabLayout tabLayout;
private ViewPager viewPager;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_pagina_inicial_cliente);
tabLayout = findViewById(R.id.tabLayoutCliente);
viewPager = findViewById(R.id.viewPagerCliente);
ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
//fragments a adicionar
adapter.addFragment(new FragmentMenuEncomendas(), "Encomendas");
adapter.addFragment(new FragmentMenuOpcoes(), "Opções");
//inicializar o tab layout
viewPager.setAdapter(adapter);
tabLayout.setupWithViewPager(viewPager);
sharedpreferences = getSharedPreferences("user", Context.MODE_PRIVATE);
if (sharedpreferences.getInt("tipo",0)==3) {
Log.d("USER_DEBUG","Cliente");
FragmentMenuEncomendas fragmentMenuEncomendas = new FragmentMenuEncomendas();
//THE ERROR IS HERE
fragmentMenuEncomendas.getActivity().findViewById(R.id.textViewEncomendas).setVisibility(View.GONE);
}
}
}
The FragmentMenuEncomenda
class:
public class FragmentMenuEncomendas extends Fragment {
View v;
public FragmentMenuEncomendas(){
}
@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
v = inflater.inflate(R.layout.encomendas_fragment, container, false);
return v;
}
}
The xml file:
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="@+id/textViewEncomendas"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/app_name"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
All the answers I've searched didn't work, I don't know if it's because I'm trying to change the visibility inside the on create method.
Because view is not created when you call the function.
public class FragmentMenuEmpresas extends Fragment {
View v;
View textView;
boolean isTextViewShow = false;
boolean isViewCreated = false;
public FragmentMenuEmpresas() {
}
@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
v = inflater.inflate(R.layout.empresas_fragment, container, false);
textView = v.findViewById(R.id.textViewEncomendas);
return v;
}
@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
if (isTextViewShow) {
textView.setVisibility(View.VISIBLE);
} else {
textView.setVisibility(View.GONE);
}
isViewCreated = true;
}
void setIsTextViewShow() {
if (isViewCreated) {
textView.setVisibility(View.VISIBLE);
} else {
isTextViewShow = true;
}
}
void setIsTextViewGone() {
if (isViewCreated) {
textView.setVisibility(View.GONE);
} else {
isTextViewShow = false;
}
}
}
then you can call the setIsTextViewShow
or setIsTextViewGone
anytime you want
FragmentMenuEncomendas fragmentMenuEncomendas = new FragmentMenuEncomendas();
fragmentMenuEncomendas.setIsTextViewShow();//show
fragmentMenuEncomendas.setIsTextViewGone();//gone
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