Toggle fullscreen immersive mode example

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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=".MainActivity">

    <TextView
        android:id="@+id/textView1"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:text="Hello World!"
        android:padding="10dp"
        android:textSize="25dp" />

</LinearLayout>

package com.example.dialog;

import android.os.Bundle;
import android.view.Menu;

import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.FragmentTransaction;

public class MainActivity extends AppCompatActivity {

    public static final String FRAGTAG = "ImmersiveModeFragment";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

      // Add ImmersiveModeFragment to FragmentTransaction
        if (getSupportFragmentManager().findFragmentByTag(FRAGTAG) == null ) {
            FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
            ImmersiveModeFragment fragment = new ImmersiveModeFragment();
            transaction.add(fragment, FRAGTAG);
            transaction.commit();
        }
    }

  // Create options menu with res/menu/main.xml
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

}

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <item android:id="@+id/sample_action"
        app:showAsAction="never"
        android:title="Toggle Immersive Mode" />
</menu>

package com.example.dialog;

import android.os.Bundle;
import android.view.MenuItem;
import android.view.View;

import androidx.annotation.NonNull;
import androidx.fragment.app.Fragment;

public class ImmersiveModeFragment extends Fragment {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setHasOptionsMenu(true);
    }

    @Override
    public void onViewCreated(@NonNull View v, Bundle savedInstanceState) {
        super.onViewCreated(v, savedInstanceState);

    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        if (item.getItemId() == R.id.sample_action) {
            toggleFullscreen();
        }
        return true;
    }

    public void toggleFullscreen() {
        int newUiOptions = getActivity().getWindow().getDecorView().getSystemUiVisibility();

        newUiOptions ^= View.SYSTEM_UI_FLAG_HIDE_NAVIGATION;
        newUiOptions ^= View.SYSTEM_UI_FLAG_FULLSCREEN;
        newUiOptions ^= View.SYSTEM_UI_FLAG_IMMERSIVE;
        getActivity().getWindow().getDecorView().setSystemUiVisibility(newUiOptions);
    }

}