public class MainActivity extends AppCompatActivity {
    private CodeScanner mCodeScanner;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        CodeScannerView scannerView = findViewById(R.id.scanner_view);
        // Use builder
        mCodeScanner = CodeScanner.builder()
                /*camera can be specified by calling .camera(cameraId),
                first back-facing camera on the device by default*/
                /*code formats*/
                .formats(CodeScanner.ALL_FORMATS)/*List<BarcodeFormat>*/
                /*or .formats(BarcodeFormat.QR_CODE, BarcodeFormat.DATA_MATRIX, ...)*/
                /*or .format(BarcodeFormat.QR_CODE) - only one format*/
                /*auto focus*/
                .autoFocus(true).autoFocusMode(AutoFocusMode.SAFE).autoFocusInterval(2000L)
                /*flash*/
                .flash(false)
                /*decode callback*/
                .onDecoded(new DecodeCallback() {
                    @Override
                    public void onDecoded(@NonNull final Result result) {
                        runOnUiThread(new Runnable() {
                            @Override
                            public void run() {
                                Toast.makeText(MainActivity.this, result.getText(),
                                        Toast.LENGTH_LONG).show();
                            }
                        });
                    }
                })
                /*error callback*/
                .onError(new ErrorCallback() {
                    @Override
                    public void onError(@NonNull final Exception error) {
                        runOnUiThread(new Runnable() {
                            @Override
                            public void run() {
                                Toast.makeText(MainActivity.this, error.getMessage(),
                                        Toast.LENGTH_LONG).show();
                            }
                        });
                    }
                }).build(this, scannerView);
        // Or use constructor to create scanner with default parameters
        // All parameters can be changed after scanner created
        // mCodeScanner = new CodeScanner(this, scannerView);                
        // mCodeScanner.setDecodeCallback(...);                
        scannerView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                mCodeScanner.startPreview();
            }
        });
    }

    @Override
    protected void onResume() {
        super.onResume();
        mCodeScanner.startPreview();
    }

    @Override
    protected void onPause() {
        mCodeScanner.releaseResources();
        super.onPause();
    }
}