android zxing intentintegrator

Question

I've written the following code that works fine if you decide to scan a QR code (using zxing) and store it in private storage but in case you decide to cancel scanning, it crashes and the file previously stored content disappears.

I think it might be a design error, not sure why.

Below is relevant code

...

/**
 * menu generation
 */
@Override
public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.menu, menu);
    return true;
}

/**
 * menu handling
 */
@Override
public boolean onOptionsItemSelected(MenuItem item) {
    Context context = getApplicationContext();
    Toast toast = Toast.makeText(context, "", Toast.LENGTH_LONG);
    toast.setGravity(Gravity.FILL_HORIZONTAL, 0, 0);
    switch (item.getItemId()) {
        case R.id.qrScan:
            IntentIntegrator integrator = new IntentIntegrator(this);
            integrator.initiateScan();
            return true;
        case R.id.qrReset:
            File dir = getFilesDir();
            File file = new File(dir, qrCodeFile);
            boolean deleted = file.delete();
            return true;
        case R.id.appClose:
            this.finish();
            return true;
        default:
            return super.onOptionsItemSelected(item);
    }
} 

...

    public void onActivityResult(int requestCode, int resultCode, Intent intent) {
    IntentResult scanResult = IntentIntegrator.parseActivityResult(requestCode, resultCode, intent);
    Context context = getApplicationContext();
    Toast toast = Toast.makeText(context, "", Toast.LENGTH_SHORT);
    if (scanResult != null) {
        FileOutputStream fos = null;
        CharSequence text = scanResult.getContents();
        try {
            fos = openFileOutput(qrCodeFile, Context.MODE_PRIVATE);
            try {
                fos.write(text.toString().getBytes());
                fos.close();
                toast.setGravity(Gravity.FILL_HORIZONTAL, 0, 0);
                toast.setText("Code saved");
                toast.show();
            } catch (IOException ex) {
                toast.setGravity(Gravity.FILL_HORIZONTAL, 0, 0);
                toast.setText("Invalid code");
                toast.show();
                Logger.getLogger(MainActivity.class.getName()).log(Level.SEVERE, null, ex);
            }
        } catch (FileNotFoundException ex) {
                toast.setGravity(Gravity.FILL_HORIZONTAL, 0, 0);
                toast.setText("Error while saving");
                toast.show();
            Logger.getLogger(MainActivity.class.getName()).log(Level.SEVERE, null, ex);
        }
    }   else {
        toast.setGravity(Gravity.FILL_HORIZONTAL, 0, 0);
        toast.setText("Invalid code");
        toast.show();           
    }  
}

Answer 1

You need to check the resultCode. If the scan is canceled there is no information about the barcode value. With the resultCode you can check if the operation was successful or not.

if(resultCode == RESULT_OK) {
    // scan successful
} else {
    // no result
}