Fragment doesn't change after item click Navigation Drawer

Question

I'm building an app which contains a NavigationDrawer to navigate between Fragments. For some reason, when pressing on any item in the Navigation Drawer the item just marks itself and doesn't change the fragment (tried debug but the item clicks doesn't calls the functions)

The fragment is not loading in first click..i have to press twice to reload the fragment

Main Activity:

public class MainActivity extends AppCompatActivity {
private NavigationView navigationView;
private DrawerLayout drawer;
private View navHeader;
private ImageView imgNavHeaderBg, imgProfile;
private TextView txtName, txtCity;
private Toolbar toolbar;
private FloatingActionButton fab;

// urls to load user profile & background
private static final String urlNavHeaderBg = "";
private static final String urlProfileImg = "";

//current menu pressed
public static int navItemIndex = 0;

//tags for fragments
private static final String TAG_HOME = "home";
private static final String TAG_PROFILE = "profile";
private static final String TAG_RATEUS = "rate us";
private static final String TAG_SCORE = "rate score";
private static final String TAG_NOTIFICATIONS = "notifications";
private static final String TAG_SETTINGS = "settings";
public static String CURRENT_TAG = TAG_HOME;

private String[] activityTitles;
private boolean shouldLoadHomeFragOnBackPress = true;
private Handler mHandler;


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

    toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);
    mHandler = new Handler();
    drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    navigationView = (NavigationView) findViewById(R.id.nav_view);
    fab = (FloatingActionButton) findViewById(R.id.fab);

    //nav view header
    navHeader = navigationView.getHeaderView(0);
    txtName = (TextView) navHeader.findViewById(R.id.name);
    txtCity = (TextView) navHeader.findViewById(R.id.city);
    imgNavHeaderBg = (ImageView) navHeader.findViewById(R.id.img_header_bg);
    imgProfile = (ImageView) navHeader.findViewById(R.id.img_profile);

    //load the toolbar titles
    activityTitles = getResources().getStringArray(R.array.nav_item_activity_titles);

    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Snackbar.make(view, "Make action here", Snackbar.LENGTH_LONG).setAction("Action", null).show();
        }
    });

    //load the navigator header data
    loadNavHeader();

    //initialize nav menu
    setUpNavigationView();

    if (savedInstanceState == null) {
        navItemIndex = 0;
        CURRENT_TAG = TAG_HOME;
        loadHomeFragment();
    }
}

private void loadNavHeader() {
    txtName.setText("My Name");
    txtCity.setText("Somewhere, Europe");

    Glide.with(this).load(urlNavHeaderBg).crossFade().diskCacheStrategy(DiskCacheStrategy.ALL).into(imgNavHeaderBg);
    Glide.with(this).load(urlProfileImg).thumbnail(0.5f).bitmapTransform(new CircleTransform(this)).diskCacheStrategy(DiskCacheStrategy.ALL).into(imgProfile);

    navigationView.getMenu().getItem(4).setActionView(R.layout.menu_dot);
}

private void loadHomeFragment() {
    selectNavMenu();
    setToolBarTitle();

    if (getSupportFragmentManager().findFragmentByTag(CURRENT_TAG) != null) {
        drawer.closeDrawers();
        toggleFab();
        return;
    }
    Runnable mPendingRunnable = new Runnable() {
        @Override
        public void run() {
            Fragment fragment = getHomeFragment();
            FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
            fragmentTransaction.setCustomAnimations(android.R.anim.fade_in, android.R.anim.fade_out);
            fragmentTransaction.replace(R.id.frame, fragment, CURRENT_TAG);
            fragmentTransaction.commitAllowingStateLoss();
        }
    };
    if (mPendingRunnable != null) {
        mHandler.post(mPendingRunnable);
    }
    toggleFab();

    drawer.closeDrawers();
    invalidateOptionsMenu();
}

private Fragment getHomeFragment() {
    switch (navItemIndex) {
        case 0:
            HomeFragment homeFragment = new HomeFragment();
            return homeFragment;
        case 1:
            ProfileFragment profileFragment = new ProfileFragment();
            return profileFragment;
        case 2:
            RateusFragment rateusFragment = new RateusFragment();
            return rateusFragment;
        case 3:
            ScoreFragment scoreFragment = new ScoreFragment();
            return scoreFragment;
        case 4:
            NotificationsFragment notificationsFragment = new NotificationsFragment();
            return notificationsFragment;
        case 5:
            SettingsFragment settingsFragment = new SettingsFragment();
            return settingsFragment;
        default:
            return new HomeFragment();
    }
}

private void setToolBarTitle() {
    getSupportActionBar().setTitle(activityTitles[navItemIndex]);
}

private void selectNavMenu() {
    navigationView.getMenu().getItem(navItemIndex).setCheckable(true);
}

private void setUpNavigationView() {
    navigationView.setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener() {
        @Override
        public boolean onNavigationItemSelected(@NonNull MenuItem menuItem) {
            switch (menuItem.getItemId()) {
                case R.id.nav_home:
                    navItemIndex = 0;
                    CURRENT_TAG = TAG_HOME;
                    break;
                case R.id.nav_profile:
                    navItemIndex = 1;
                    CURRENT_TAG = TAG_PROFILE;
                    break;
                case R.id.nav_rateus:
                    navItemIndex = 2;
                    CURRENT_TAG = TAG_RATEUS;
                    break;
                case R.id.nav_score:
                    navItemIndex = 3;
                    CURRENT_TAG = TAG_SCORE;
                    break;
                case R.id.nav_notifications:
                    navItemIndex = 4;
                    CURRENT_TAG = TAG_NOTIFICATIONS;
                    break;
                case R.id.nav_settings:
                    navItemIndex = 5;
                    CURRENT_TAG = TAG_SETTINGS;
                    break;
                case R.id.nav_about_us:
                    startActivity(new Intent(MainActivity.this, AboutUsActivity.class));
                    drawer.closeDrawers();
                    return true;
                case R.id.nav_terms:
                    startActivity(new Intent(MainActivity.this, TermsActivity.class));
                    drawer.closeDrawers();
                    return true;
                default:
                    navItemIndex = 0;
            }
            if (menuItem.isChecked()) {
                menuItem.setChecked(false);
            } else {
                menuItem.setChecked(true);
            }
            menuItem.setChecked(true);

            return true;
        }
    });

    ActionBarDrawerToggle actionBarDrawerToggle = new ActionBarDrawerToggle(this, drawer, toolbar, R.string.openDrawer, R.string.closeDrawer) {

        @Override
        public void onDrawerClosed(View drawerView) {
            //when nav closed this will triggered - leaving blank so nothing won't happen
            super.onDrawerClosed(drawerView);
        }

        @Override
        public void onDrawerOpened(View drawerView) {
            //when nav opened this will triggered - leaving blank so nothing won't happen
            super.onDrawerOpened(drawerView);
        }
    };
    drawer.addDrawerListener(actionBarDrawerToggle);
    actionBarDrawerToggle.syncState();
}

@Override
public void onBackPressed() {
    if (drawer.isDrawerOpen(GravityCompat.START)) {
        drawer.closeDrawers();
        return;
    }
    if (shouldLoadHomeFragOnBackPress) {
        if (navItemIndex != 0) {
            navItemIndex = 0;
            CURRENT_TAG = TAG_HOME;
            loadHomeFragment();
            return;
        }
    }
    super.onBackPressed();
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    if (navItemIndex == 0) {
        getMenuInflater().inflate(R.menu.main, menu);
    }
    if (navItemIndex == 4) {
        getMenuInflater().inflate(R.menu.notifications, menu);
    }
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    int id = item.getItemId();

    if (id == R.id.action_logout) {
        Toast.makeText(getApplicationContext(), "Logout user!", Toast.LENGTH_LONG).show();
        return true;
    }
    if (id == R.id.action_mark_all_read) {
        Toast.makeText(getApplicationContext(), "All marked as read!", Toast.LENGTH_LONG).show();
    }
    if (id == R.id.action_clear_notifications) {
        Toast.makeText(getApplicationContext(), "All Cleared!", Toast.LENGTH_LONG).show();
    }
    return super.onOptionsItemSelected(item);
}

private void toggleFab() {
    if (navItemIndex == 0)
        fab.show();
    else
        fab.hide();
}

}

activity_main.xml:

<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout
    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/drawer_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    tools:openDrawer="start"
    tools:context=".activity.MainActivity">
<include
    layout="@layout/app_bar_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

<android.support.design.widget.NavigationView
    android:id="@+id/nav_view"
    android:layout_width="wrap_content"
    android:layout_height="match_parent"
    android:layout_gravity="start"
    android:fitsSystemWindows="true"
    app:headerLayout="@layout/nav_header_main"
    app:menu="@menu/activity_main_drawer" />

Answer 1

There are couple of problems with the code:

Make sure u add break in switch:

case R.id.nav_about_us:
    startActivity(new Intent(MainActivity.this, AboutUsActivity.class));
    drawer.closeDrawers();
    break;  //add break
case R.id.nav_terms:
    startActivity(new Intent(MainActivity.this, TermsActivity.class));
    drawer.closeDrawers();
    break;  
default:
    navItemIndex = 0;
     break;

Also your fragment not loading as you are not calling the function properly:

in your Switch case:

case R.id.nav_home:
    navItemIndex = 0;
    CURRENT_TAG = TAG_HOME;
    Fragment fragment = getHomeFragment();  //get fragment based on index
    ReplaceFragment(fragment);  //now replace them and load new one
    drawer.closeDrawers();
    break;

in ReplaceFragment method write:

public void ReplaceFragment(Fragment r_fragment) {
    if (r_fragment != null) {
        FragmentManager fragmentManager = getSupportFragmentManager();
        fragmentManager.beginTransaction().replace(R.id.frame, r_fragment).commit();

    } else {
        // error in creating fragment
    }

}

Also overWrite following methods:

 @Override
public void onDrawerOpened(View drawerView) {
    super.onDrawerOpened(drawerView);
    drawerView.bringToFront();  //add this two lines
    drawerView.requestLayout();
}

 @Override
    protected void onPostCreate(Bundle savedInstanceState) {
        super.onPostCreate(savedInstanceState);
        // Sync the toggle state after onRestoreInstanceState has occurred.
        actionBarDrawerToggle.syncState();
    }