Hiding AppBarLayout upon viewing a certain Fragment

Question

i am new to android and trying to implement a main activity with tabs, each tab contains a fragment, and upon one of the fragments i would like the whole app bar to disappear (its intended to be a camera fragment) , leaving the certain fragment in FullScreen mode, this is what i have so far:

file : MainActivity.java

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
       //this.getWindow().addFlags(WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS);
        SectionsPagerAdapter sectionsPagerAdapter = new SectionsPagerAdapter(this, getSupportFragmentManager());
        ViewPager viewPager = findViewById(R.id.view_pager);
        viewPager.setAdapter(sectionsPagerAdapter);
        TabLayout tabs = findViewById(R.id.tabs);
        tabs.setupWithViewPager(viewPager);
        FloatingActionButton fab = findViewById(R.id.fab);


        final AppBarLayout bar = findViewById(R.id.appBarLayout2); // the app bar layout that i want gone

        tabs.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
            @Override
            public void onTabSelected(TabLayout.Tab tab)
            {
                
            }

            @Override
            public void onTabUnselected(TabLayout.Tab tab)
            {

            }

            @Override
            public void onTabReselected(TabLayout.Tab tab)
            {
                onTabSelected(tab);
            }
        });

as you can see, i am trying to implement a tabs listener along with a ViewPager, i have tried implementing inside an if statement on the bar.position():

• ((AppCompatActivity) getActivity()).getSupportActionBar().hide(); - app crashes
• getActionBar().hide() - returns null and also crashes
• getWindow().setFlags( WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN); - doesnt work

file : main_activity.xml

<androidx.constraintlayout.widget.ConstraintLayout 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:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".UIActivity">

    <com.google.android.material.appbar.AppBarLayout
        android:id="@+id/appBarLayout2"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:theme="@style/AppTheme.AppBarOverlay"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="@+id/view_pager">

        <ImageView
            android:id="@+id/imageView1"
            android:layout_width="80dp"
            android:layout_height="50dp"
            android:layout_gravity="center"
            android:src="@mipmap/logo1" />

        <com.google.android.material.tabs.TabLayout
            android:id="@+id/tabs"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:background="?attr/colorPrimary"
            app:tabIndicatorColor="#ffffff"
            app:tabIndicatorHeight="2dp" /><!-- #86B2E8 -->
    </com.google.android.material.appbar.AppBarLayout>

    <androidx.viewpager.widget.ViewPager
        android:id="@+id/view_pager"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <com.google.android.material.floatingactionbutton.FloatingActionButton
        android:id="@+id/fab"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginEnd="8dp"
        android:layout_marginRight="8dp"
        android:layout_marginBottom="16dp"
        app:layout_constraintBottom_toBottomOf="@+id/view_pager"
        app:layout_constraintEnd_toEndOf="parent"
        app:srcCompat="@android:drawable/ic_dialog_email" />
</androidx.constraintlayout.widget.ConstraintLayout>

the cameraFragment.java and xml files are a standard files, i still do not know how i can hide the app bar when a user clicks on the camera tab, and return it once he swipes back to an another Fragment.

Answer 1

the action bar belongs to the activity, not your fragment. but you can create a style with no action bar and change the style on the beginning of the fragment.

based on https://stackoverflow.com/a/15496425/8244139 , you should use the code below:

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

    // create ContextThemeWrapper from the original Activity Context with the custom theme
    final Context contextThemeWrapper = new ContextThemeWrapper(getActivity(), R.style.yourCustomTheme);

    // clone the inflater using the ContextThemeWrapper
    LayoutInflater localInflater = inflater.cloneInContext(contextThemeWrapper);

    // inflate the layout using the cloned inflater, not default inflater
    return localInflater.inflate(R.layout.yourLayout, container, false);
}