[Demonstration 1]

[Buggy Method]
@SuppressWarnings("StatementWithEmptyBody")
@Override
public boolean onNavigationItemSelected(MenuItem item) {
    // Handle navigation view item clicks here.
    int id = item.getItemId();
    if (id == R.id.nav_game_groups) {
        fragmentManager.beginTransaction().replace(R.id.frame_content, groupFragment).commit();
    } else if (id == R.id.nav_game_histroy) {
        if (mAuth.getCurrentUser() == null) {
            startActivity(new Intent(this, LoginActivity.class));
        } else {
            historyFragment = GameHistoryFragment.newInstance(mAuth.getCurrentUser().getUid());
            fragmentManager.beginTransaction().replace(R.id.frame_content, historyFragment).commit();
        }
    } else if (id == R.id.nav_my_words) {
        Timber.d("nav my words clicked");
        Toast.makeText(MainActivity.this, "Add your own words will be available next version", Toast.LENGTH_SHORT).show();
    } else if (id == R.id.nav_setting) {
        Timber.d("nav setting clicked");
        startSetting();
    } else if (id == R.id.nav_about) {
        Timber.d("nav about clicked");
        startActivity(new Intent(MainActivity.this, AboutActivity.class));
    }
    drawer.closeDrawer(GravityCompat.START);
    return true;
}

[Buggy Hunk]
} else if (id == R.id.nav_game_histroy) {

[Patch]
} else if (id == R.id.nav_game_history) {

[Demonstration 2]

[Buggy Method]
@Override
public void onBackPressed() {
    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    if (drawer.isDrawerOpen(GravityCompat.START)) {
        drawer.closeDrawer(GravityCompat.START);
    } else {
        super.onBackPressed();
    }
}

[Buggy Hunk]
if (drawer.isDrawerOpen(GravityCompat.START)) {

[Patch]
if (drawer != null && drawer.isDrawerOpen(GravityCompat.START)) {

[Demonstration 3]

[Buggy Method]
public Parent createContent(String id, Stage window) {
    BorderPane layout = new BorderPane();
    FacultyDb obj = new FacultyDb();
    listing = obj.Proctee(id);
    List<HBoxCell> list = new ArrayList<>();
    for (StudentModel stud : listing) {
        list.add(new HBoxCell(stud.getName() + " ", "View Profile", stud.getId(), window));
    }
    ObservableList<HBoxCell> myObservableList = FXCollections.observableList(list);
    listView.setItems(myObservableList);
    layout.setCenter(listView);
    return layout;
}

[Buggy Hunk]
list.add(new HBoxCell(stud.getName()+" "  , "View Profile" ,stud.getId(),window));

[Patch]
list.add(new HBoxCell(stud.getName()+" "  , "View Profile" ,stud.getId(),window,id));