First Fragment Remains In The Background After Transition

I am currently trying to create an app having a splash screen, a login screen and a register screen. The only way to achieve exactly what I need is through fragments. Though when I

Solution 1:

The problem is that you cannot replace fragments added via the <fragment> tag.

Instead, you should either:

1) Switch to FragmentContainerView, which was added in Fragment 1.2.0. It does not suffer from the same issue as the <fragment> tag and lets you do replace operations without issues:

<?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:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".StartActivity"
    android:background="@mipmap/background">

    <androidx.fragment.app.FragmentContainerView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/viewpagerstart"
        android:layout_centerInParent="true"
        android:name="com.example.distributedsystemsui.SplashFragment">

    </androidx.fragment.app.FragmentContainerView>
</RelativeLayout>

2) Use a FrameLayout in your layout and manually add the SplashFragment in your activity (this is essentially what FragmentContainerView does for you):

<?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:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".StartActivity"
    android:background="@mipmap/background">

    <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/viewpagerstart"
        android:layout_centerInParent="true">

    </FrameLayout>
</RelativeLayout>

which means you need to add the SplashFragment manually:

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_start);
    if (savedInstanceState == null) {
        getSupportFragmentManager().beginTransaction()
            .add(R.id.viewpagerstart, new SplashFragment())
            .commit()
    }
}

Solution 2:

I think it is better to do the fragment transactions from your activity instead of doing it from your fragment. You might consider having functions in your MainActivity as follows.

public class StartActivity extends AppCompatActivity {

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

    public void goToLoginFragment() {
        FragmentTransaction ft = getFragmentManager().beginTransaction();
        ft.setCustomAnimations(R.anim.slide_enter_left, R.anim.slide_exit_left,
                R.anim.slide_enter_right, R.anim.slide_exit_right);
        LoginFragment loginFragment = LoginFragment.newInstance();
        ft.replace(R.id.viewpagerstart, loginFragment);
        ft.commit();
    }

    public void goToRegisterFragment() {
        FragmentTransaction ft = getFragmentManager().beginTransaction();
        ft.setCustomAnimations(R.anim.slide_enter_left, R.anim.slide_exit_left,
                R.anim.slide_enter_right, R.anim.slide_exit_right);
        LoginFragment registerFragment = RegisterFragment.newInstance();
        ft.replace(R.id.viewpagerstart, registerFragment);
        ft.commit();
    }

    @Override
    public void onBackPressed(){
        Toast.makeText(getApplicationContext(), "Back button is disabled", Toast.LENGTH_SHORT).show();
    }
}

And then from your SplashFragment call the function that is defined in your activity.

Handler handler = new Handler();
handler.postDelayed(new Runnable() {
    public void run() {
        ((MainActivity) getActivity()).goToLoginFragment();
    }
}, 3000);

I hope that solves the problem.