Can't properly hide the bottom navigation bar

Question

I have created a drawer activity from the android studio templates and i did activate che full sticky immersive mode so that i don't always see the titlebar and the bottom navigation bar but the fact is that the bar is still there occuping space on the screen and making me unable to put items on it (overlap things with the bar). I want the bar to not be there at all and only show up then the someon swipes up or down on the screen and, when showing up, overlapping any item position on the bottom of the screen. Look at this examples:

How it should be

How it is

Also, i put this code in the MainActivity to use the sticky full immersione mode

    @Override
    public void onWindowFocusChanged(boolean hasFocus) {
        super.onWindowFocusChanged(hasFocus);
        if (hasFocus) {
            hideSystemUI();
        }
    }

    private void hideSystemUI() {
        // Enables regular immersive mode.
        // For "lean back" mode, remove SYSTEM_UI_FLAG_IMMERSIVE.
        // Or for "sticky immersive," replace it with SYSTEM_UI_FLAG_IMMERSIVE_STICKY
        View decorView = getWindow().getDecorView();
        decorView.setSystemUiVisibility(
                View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY
                        | View.SYSTEM_UI_FLAG_LAYOUT_STABLE // Set the content to appear under the system bars so that the
                        | View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION// content doesn't resize when the system bars hide and show.
                        | View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
                        // Hide the nav bar and status bar
                        | View.SYSTEM_UI_FLAG_HIDE_NAVIGATION
                        | View.SYSTEM_UI_FLAG_FULLSCREEN);
    }

    // Shows the system bars by removing all the flags
// except for the ones that make the content appear under the system bars.
    private void showSystemUI() {
        View decorView = getWindow().getDecorView();
        decorView.setSystemUiVisibility(
                View.SYSTEM_UI_FLAG_LAYOUT_STABLE
                        | View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION
                        | View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN);
    }

This one is the Manifest

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.prova3">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@android:style/Theme.NoTitleBar.Fullscreen">
        <activity
            android:name=".MainActivity"
            android:label="@string/app_name"
            android:theme="@style/AppTheme.NoActionBar">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

This one is the xml of the specific fragment i posted the screen of:

<?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"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/background"
    tools:context=".ui.login.LoginFragment">


    <TextView
        android:id="@+id/textView2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="104dp"
        android:text="Bentornato"
        android:textColor="@android:color/black"
        android:textSize="20sp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <EditText
        android:id="@+id/editText2"
        android:layout_width="325dp"
        android:layout_height="46dp"
        android:layout_marginTop="148dp"
        android:ems="10"
        android:inputType="textPersonName"
        android:hint="Email"
        android:textColorHint="@android:color/white"
        android:textColor="@android:color/white"
        android:backgroundTint="@android:color/white"
        app:layout_constraintEnd_toEndOf="parent"
        android:drawableRight="@drawable/ic_user"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/textView2" />

    <EditText
        android:id="@+id/editText3"
        android:layout_width="322dp"
        android:layout_height="46dp"
        android:layout_marginTop="16dp"
        android:ems="10"
        android:hint="Password"
        android:inputType="textPassword"
        android:textColor="@android:color/white"
        android:backgroundTint="@android:color/white"
        android:textColorHint="@android:color/white"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.483"
        app:layout_constraintStart_toStartOf="parent"
        android:drawableRight="@drawable/ic_key"
        app:layout_constraintTop_toBottomOf="@+id/editText2" />

    <Button
        android:id="@+id/button"
        android:layout_width="114dp"
        android:layout_height="33dp"
        android:layout_marginTop="76dp"
        android:background="@drawable/button_bg"
        android:backgroundTint="#7AFFFFFF"
        android:text="Login"
        android:textColor="@android:color/white"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.498"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/editText3" />

    <ImageButton
        android:id="@+id/backButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="16dp"
        android:layout_marginTop="16dp"
        android:backgroundTint="#00FFFFFF"
        android:src="@drawable/ic_back_arrow"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

And this one is the one of the main activity that hosts the fragments:

<?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"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:showIn="@layout/app_bar_main">

    <fragment
        android:id="@+id/nav_host_fragment"
        android:name="androidx.navigation.fragment.NavHostFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:defaultNavHost="true"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:navGraph="@navigation/mobile_navigation" />
</androidx.constraintlayout.widget.ConstraintLayout>

Answer 1

对我有用的是将以下内容添加到父 XML 中：

android:fitsSystemWindows="true"