[Demonstration 1]

[Buggy Method]
private void deleteGoogleToken() {
    // call expire google token
    Auth.GoogleSignInApi.revokeAccess(mGoogleApiClient).setResultCallback(new ResultCallback<Status>() {

        @Override
        public void onResult(@NonNull Status status) {
            // delete google token
            mEditor.putString(getString(R.string.google_token), null);
            mEditor.commit();
            Toast.makeText(getContext(), "disconnect google successfully!!", Toast.LENGTH_SHORT).show();
        }
    });
}

[Buggy Hunk]
mEditor.putString(getString(R.string.google_token), null);

[Patch]
mEditor.putString(getString(R.string.google_token), "");

[Demonstration 2]

[Buggy Method]
void createUI() {
    Log.d(TAG, "createUI()...");
    modelManager = ModelManager.getInstance(ActivityMain.this);
    Status status = modelManager.getStatus();
    Log.d(TAG, "createUI()...status=" + status.getRank());
    if (status.getRank() == Status.RANK_CONFIG && status.getStatus() != Status.SUCCESS)
        showDownloadConfigWindow();
    else {
        Log.d(TAG, "here");
        updateUI();
    }
}

[Buggy Hunk]
Log.d(TAG, "createUI()...status=" + status.getRank());

[Patch]
Log.d(TAG, "createUI()...status=" + status.log());

[Demonstration 3]

[Buggy Method]
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_home);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);
    FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
    fab.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View view) {
            startActivity(new Intent(HomeActivity.this, NewAdActivity.class));
        }
    });
    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
    drawer.setDrawerListener(toggle);
    toggle.syncState();
    NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
    navigationView.setNavigationItemSelectedListener(this);
}

[Buggy Hunk]
startActivity(new Intent(HomeActivity.this, NewAdActivity.class));

[Patch]
onFloatingActionButtonClick();