TitoloNascosto

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


    //Initialising toolbar.
    toolbar = (Toolbar) findViewById(R.id.toolbar);


    //Setting toolbar as Actionbar.
    setSupportActionBar(toolbar);

    //Initialising NavigationView
    navigationView = (NavigationView) findViewById(R.id.navigation_view);
    //Setting OnNavigationItemSelectedListener to the Navigation View.
    //This is used to perform specific action when an item is clicked.


navigationView.setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener() {

    @Override
    public boolean onNavigationItemSelected(MenuItem menuItem) {
                toolbar.setLogo(R.drawable.ic_launcher);
	        drawerLayout.closeDrawers();


switch (menuItem.getItemId()){
            case R.id.list_item_0:
                setTitle(R.string.title1);
                setFragment(0, Fragment1.class);
                return true;
            case R.id.list_item_1:
                setTitle(R.string. title2);
                setFragment(1, Fragment2.class);
                return true;
            case R.id.list_item_2:
                setTitle(R.string. title3);
                setFragment(2, Fragment3.class);
                return true;
            case R.id.list_item_3:
                setTitle(R.string. title4);
                setFragment(4, Fragment4.class);
                return true;
            default:
                Toast.makeText(getApplicationContext(),"Something went wrong",Toast.LENGTH_SHORT).show();
                return true;
        }

    }
});

. . .

if(savedInstanceState != null){
//effettua il restore di quanto salvato (allo stato attuale solo del logo)

    toolbar.setLogo(R.drawable.ic_launcher);
}
else{
//se nulla è salvato effettua una nuova istanziazione
    setFragment(0, Fragment1.class);
    setTitle(R.string.title1);
    toolbar.setLogo(R.drawable.ic_launcher);
}}


 @Override
 public void onSaveInstanceState(Bundle savedInstanceState) {

//qui per quello che ho capito dovrei richiamarmi il titolo del fragment che deve memorizzare
 super.onSaveInstanceState(savedInstanceState);
 }