MainActivity2.java

  mTextRecognizer.setProcessor(new Detector.Processor() {
                @Override
                public void release() {

                }

                @Override
                public void receiveDetections(Detector.Detections detections) {
                    SparseArray items = detections.getDetectedItems();
                    StringBuilder stringBuilder = new StringBuilder();
                    for (int i = 0; i < items.size(); ++i) {
                        TextBlock item = items.valueAt(i);
                        if (item != null && item.getValue() != null) {
                            stringBuilder.append(item.getValue() + " ");
                        }
                    }

                    final String fullText = stringBuilder.toString();
                    Handler handler = new Handler(Looper.getMainLooper());
                    handler.post(new Runnable() {
                        public void run() {
                            mTextView.setText(fullText);
                        }
                    });

                }
            });
        }