How do I load my Fragment once and save its state

Question

I have a BottomNavigation bar from Aurel Hubert in my application: https://github.com/aurelhubert/ahbottomnavigation

I have three tabs, the problem is that the second fragment is so big that it opens with a delay of 2 seconds and this causes that the animation of the bottom bar jerks. So I thought that it would be useful to load the fragment right at the beginning once and to save its state.

How can I do that? (I'm new to Android Studio)

Here is my Code: My activity_main.xml:

<?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"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:context="com.aaron.waller.mrpolitik.MainActivity"
    android:id="@+id/content_id">

    <com.aurelhubert.ahbottomnavigation.AHBottomNavigation
        android:id="@+id/myBottomNavigation_ID"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom"
        android:layout_alignParentBottom="true"/>


</RelativeLayout>

and my MainActivity.java:

public class MainActivity extends AppCompatActivity implements AHBottomNavigation.OnTabSelectedListener {

    private AHBottomNavigation bottomNavigation;
    private FragenFragment fragenFragment;
    private StatistikenFragment statistikenFragment;
    private ParteienFragment parteienFragment;




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

        parteienFragment = new ParteienFragment();
        statistikenFragment = new StatistikenFragment();
        fragenFragment = new FragenFragment();


        bottomNavigation = (AHBottomNavigation) findViewById(R.id.myBottomNavigation_ID);
        bottomNavigation.setOnTabSelectedListener(this);
        bottomNavigation.setDefaultBackgroundColor(Color.BLUE);
        this.createNavItems();

    }


    //Create items, add them to bar, set propertied and set current item
    private void createNavItems() {
        //CREATE ITEMS
        AHBottomNavigationItem ohnemundItem = new AHBottomNavigationItem("Parteien", R.drawable.parteienicon);
        AHBottomNavigationItem grinseItem = new AHBottomNavigationItem("Statistiken", R.drawable.statsicon);
        AHBottomNavigationItem lachItem = new AHBottomNavigationItem("Fragen", R.drawable.fragenicon);

        //ADD THEM to bar
        bottomNavigation.addItem(ohnemundItem);
        bottomNavigation.addItem(grinseItem);
        bottomNavigation.addItem(lachItem);


        //set properties
        bottomNavigation.setDefaultBackgroundColor(Color.parseColor("#FEFEFE"));

        //set current item
        bottomNavigation.setCurrentItem(0);

    }

    @Override
    public void onTabSelected(int position, boolean wasSelected) {
        if (position == 0) {
        getSupportFragmentManager().beginTransaction().replace(R.id.content_id, parteienFragment).commit();
        } else if (position == 1) {
        getSupportFragmentManager().beginTransaction().replace(R.id.content_id, statistikenFragment).commit();
        } else if (position == 2) {
        getSupportFragmentManager().beginTransaction().replace(R.id.content_id, fragenFragment).commit();
        }
    }
}

Answer 1

to retain a fragment a first step is to set this on the fragment in oncreate:

    setRetainInstance(true)

once that is done, there are a few more steps. it is explained pretty well here:

more info