Load fragments when call it and keep when switch to another fragment/activity

I was looking here some ways to do what i want, i tried some codes but nothen works. I have a app with bottom bar (3 itens), and i have one fragment for each one. The 3 fragments load a layout with webview (3 differents links, of course). What i want is switch between fragment and keep it in the background, beause when I leave fragment 1 to fragment 2, and i back to fragment 1, the fragment 1 load again, and i just want to keep it load, and the others fragments too. How can i do that ?
Thanks for the help !!

Activity Main XML

<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:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context="bandeira.thalisson.appExample.MainActivity">

<FrameLayout
    android:id="@+id/content"
    android:layout_width="match_parent"
    android:layout_height="0dp"
    android:layout_weight="1">
</FrameLayout>

<android.support.design.widget.BottomNavigationView
    android:id="@+id/navigation"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_gravity="bottom"
    android:background="?android:attr/windowBackground"
    app:menu="@menu/navigation"/>

Main Activity Java

public class MainActivity extends AppCompatActivity {

private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener
        = new BottomNavigationView.OnNavigationItemSelectedListener() {

    @Override
    public boolean onNavigationItemSelected(@NonNull MenuItem item) {
        Fragment selectedFragment = null;
        switch (item.getItemId()) {
            case R.id.navigation_item1:
                selectedFragment = Fragment1.newInstance();
                getSupportFragmentManager().beginTransaction().replace(R.id.content, selectedFragment).commit();
                return true;
            case R.id.navigation_item2:
                selectedFragment = Fragment2.newInstance();
                getSupportFragmentManager().beginTransaction().replace(R.id.content, selectedFragment).commit();
                return true;
            case R.id.navigation_item3:
                selectedFragment = Fragment3.newInstance();
                getSupportFragmentManager().beginTransaction().replace(R.id.content, selectedFragment).commit();
                return true;
        }
        return false;
    }

};

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

    BottomNavigationView navigation = (BottomNavigationView) findViewById(R.id.navigation);
    navigation.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);

    //*Iniciar um fragmento junto com o aplicativo
    FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
    transaction.replace(R.id.content, Fragment1.newInstance());
    transaction.commit();
}

Fragment Example Java

public class Google extends Fragment {

public WebView myWebView;


public static Google newInstance() {
    Googlefragment = new Google();
    return fragment;
}

public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View rootView = inflater.inflate(R.layout.webview, container, false);
    myWebView = (WebView) rootView.findViewById(R.id.WebViewLayout);
    myWebView.loadUrl("http://google.com/");

    //*Ativar JavaScript
    WebSettings webSettings = myWebView.getSettings();
    webSettings.setJavaScriptEnabled(true);


    //*Forçar links para abrir no WebView ao invés do navegador
    myWebView.setWebViewClient(new WebViewClient());

    return rootView;
}

Fragment XML

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent">

<WebView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/WebViewLayout"/>

Instead of using replace everytime in your onNavigationItemSelected, use show and hide.

Programmatically create all the fragments probably in your onCreate and in your item selected method

instead of this

getSupportFragmentManager().beginTransaction().replace(R.id.content, selectedFragment).commit();

you do

getSupportFragmentManager().beginTransaction().show(R.id.content, selectedFragment).commit();

and similarly for hiding

getSupportFragmentManager().beginTransaction().hide(R.id.content, selectedFragment).commit();

In this case, it will created only once(the first time), and subsequently will be just shown and hidden (think in terms of VISIBLE and GONE, not saying its the same, but similar)