Wie kann man die Navigationsleiste beim Öffnen eines bestimmten Fragments ausblenden?

Question

Ich bin ziemlich neu in Android-Entwicklung. Ich möchte die Navigationsleiste ausblenden, wenn der Benutzer nicht eingeloggt ist. Im Grunde wird das Login-Fragment angezeigt (besser im Vollbildmodus wie Facebook android). Wenn der Benutzer bereits angemeldet ist, wird die Navigationsleiste immer angezeigt.

MainActivity.java

public class MainActivity extends AppCompatActivity { 

private DrawerLayout navDrawerLayout; 
private Toolbar toolbar; 
private ActionBarDrawerToggle navDrawerToggle; 

private SharedPreferences pref; 

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

    toolbar = (Toolbar) findViewById(R.id.toolbar); 
    setSupportActionBar(toolbar); 

    navDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout); 

    // Find our drawer view 
    NavigationView navDrawerView = (NavigationView) findViewById(R.id.navdrawer_view); 
    // Setup drawer view 
    setupDrawerContent(navDrawerView); 

    navDrawerToggle = setupDrawerToggle(); 

    pref = getPreferences(0); 
    initFirstFrame(); 
} 

private ActionBarDrawerToggle setupDrawerToggle() { 
    return new ActionBarDrawerToggle(this, navDrawerLayout, toolbar, R.string.drawer_open, R.string.drawer_close); 
} 

private void setupDrawerContent(NavigationView navDrawerView) { 
    navDrawerView.setNavigationItemSelectedListener(
      new NavigationView.OnNavigationItemSelectedListener() { 
       @Override 
       public boolean onNavigationItemSelected(MenuItem menuItem) { 
        selectDrawerItem(menuItem); 
        return true; 
       } 


      }); 
} 

public void selectDrawerItem(MenuItem menuItem) { 
    // Create a new fragment and specify the fragment to show based on nav item clicked 
    Fragment fragment = null; 
    Class fragmentClass; 
    switch(menuItem.getItemId()) { 
     case R.id.events: 
      fragmentClass = EventsFragment.class; 
      break; 
     case R.id.pengumuman: 
      fragmentClass = NewsFragment.class; 
      break; 
     case R.id.edit_profil: 
      fragmentClass = ProfileFragment.class; 
      break; 
     default: 
      fragmentClass = EventsFragment.class; 
    } 

    try { 
     fragment = (Fragment) fragmentClass.newInstance(); 
    } catch (Exception e) { 
     e.printStackTrace(); 
    } 

    // Insert the fragment by replacing any existing fragment 
    FragmentManager fragmentManager = getSupportFragmentManager(); 
    fragmentManager.beginTransaction().replace(R.id.frame_content, fragment).commit(); 

    // Highlight the selected item has been done by NavigationView 
    menuItem.setChecked(true); 
    // Set action bar title 
    setTitle(menuItem.getTitle()); 
    // Close the navigation drawer 
    navDrawerLayout.closeDrawers(); 
} 

private void initFirstFrame(){ 
    Fragment fragment; 
    if(pref.getBoolean(Constants.IS_LOGGED_IN,false)){ 
     fragment = new ProfileFragment(); 
    }else { 
     fragment = new LoginFragment(); 
     // in this login fragment, navdrawer should be invisible, the toolbar too I guess 
    } 

    FragmentManager fragmentManager = getSupportFragmentManager(); 
    FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction(); 
    fragmentTransaction.replace(R.id.frame_content,fragment); 
    fragmentTransaction.commit(); 
} 


@Override 
public boolean onOptionsItemSelected(MenuItem item) { 
    return navDrawerToggle.onOptionsItemSelected(item) || super.onOptionsItemSelected(item); 
} 

// 'onPostCreate' called when activity start-up is complete after 'onStart()' 
// NOTE! Make sure to override the method with only a single 'Bundle' argument 
@Override 
protected void onPostCreate(Bundle savedInstanceState) { 
    super.onPostCreate(savedInstanceState); 
    // Sync the toggle state after onRestoreInstanceState has occurred 
    navDrawerToggle.syncState(); 
} 

@Override 
public void onConfigurationChanged(Configuration newConfig) { 
    super.onConfigurationChanged(newConfig); 
    // Pass any configuration change to the drawer toggles 
    navDrawerToggle.onConfigurationChanged(newConfig); 
} 

} 

Answer 1

eine Schnittstelle definieren sagen DrawerLocker:

interface DrawerLocker{ 
    public void setDrawerLocked(boolean shouldLock); 
} 

diese Schnittstelle in Ihrer Aktivität umzusetzen, die die NavigationDrawer enthält und diese Methode überschreiben.

class YourActivity implements DrawerLocker{ 
. 
. 
public void setDrawerLocked(boolean enabled){ 
    if(enabled){ 
     drawerLayout.setDrawerLockMode(DrawerLayout.LOCK_MODE_LOCKED_CLOSED); 
    }else{ 
     drawerLayout.setDrawerLockMode(DrawerLayout.LOCK_MODE_UNLOCKED); 
    } 

} 

Jetzt in Ihrem Fragment des onCreateView, rufen Sie diese Methode wie:

((DrawerLocked)getActivity()).setDrawerLocked(true); 

In Ihrem Fragment des onDestroyView, wieder die Schublade Layout aktivieren:

((DrawerLocked)getActivity()).setDrawerLocked(false); 

Answer 2

Dieser Code in Aktivität onCreate Verfahren wird Schublade sperren, wenn Sie mehr als ein Fragment im Stapel haben:

getSupportFragmentManager().addOnBackStackChangedListener(() -> { 
     if (getSupportFragmentManager().getBackStackEntryCount() > 0) { 
      mViewHolder.drawerLayout.setDrawerLockMode(DrawerLayout.LOCK_MODE_LOCKED_CLOSED); 
     } else { 
      mViewHolder.drawerLayout.setDrawerLockMode(DrawerLayout.LOCK_MODE_UNLOCKED); 
     } 
    });