My barcode reader app doesn't work. How can I run my barcode reader app?

Question

I made a project with navigation tabs. When i click barcode tab it doesnt work. Can u help me to solve this error.

This is my MainApplication.class, I used switch-case structure, when i click barcode tab it doesnt work.

case R.id.btnbarkod:
                Intent indent = new Intent(MainActivity.this, BarkodActivity.class);
                startActivity(indent);
                return true;

Here is my BarcodeActivity,

public class BarkodActivity extends AppCompatActivity implements ZXingScannerView.ResultHandler {

ZXingScannerView ScannerView;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(ScannerView);
    ScannerView = new ZXingScannerView(this);
}

@Override
public void handleResult(Result result) {
    String barkod = result.getText();
    Toast.makeText(this, barkod, Toast.LENGTH_SHORT).show();
}

@Override
protected void onPause() {
    super.onPause();
    ScannerView.stopCamera();
}

@Override
protected void onResume() {
    super.onResume();
    ScannerView.setResultHandler(this);
    ScannerView.startCamera();
}
}

Answer 1

In onCreate, you do setContentView(ScannerView);, but ScannerView is still empty at this point: it is initialized the line below. Therefore: initialize ScannerView before calling setContentView.