java - 加载新 Activity 时应用程序崩溃

Question

您好，我正在尝试在没有 Activity 扩展的情况下在我的类上加载另一个 Activity ，因此我使用了另一个具有 Activity 的类，这是我的 MAINACTIVITY 代码

  public void onCreate(Bundle savedInstanceState) {


    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_camera);
    if (null == savedInstanceState) {
      getFragmentManager()
              .beginTransaction()
              .replace(R.id.container, Camera2BasicFragment.newInstance())
              .commit();


    }


  }

  public void loadScanresults2() {

    Intent intent1 = new Intent(this, resultsActvitity.class);
    intent1.putExtra("HighScanResults", GlobalVars.scanresHigh);
    intent1.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK |
            Intent.FLAG_ACTIVITY_SINGLE_TOP);
    **startActivity(intent1);**


  }

这是 ImageCLassifier 的类

public class ImageClassifier {




  private static final String TAG = "TfLiteCameraDemo";


  private static final String MODEL_PATH = "graph.lite";


  private static final String LABEL_PATH = "labels.txt";


  private static final int RESULTS_TO_SHOW = 3;


  private static final int DIM_BATCH_SIZE = 1;

  private static final int DIM_PIXEL_SIZE = 3;

  static final int DIM_IMG_SIZE_X = 224;
  static final int DIM_IMG_SIZE_Y = 224;

  private static final int IMAGE_MEAN = 128;
  private static final float IMAGE_STD = 128.0f;

  private int[] intValues = new int[DIM_IMG_SIZE_X * DIM_IMG_SIZE_Y];

  private Interpreter tflite;

  private List<String> labelList;

  /** A ByteBuffer to hold image data, to be feed into Tensorflow Lite as inputs. */
  private ByteBuffer imgData = null;


  private float[][] labelProbArray = null;

  private float[][] filterLabelProbArray = null;
  private static final int FILTER_STAGES = 3;
  private static final float FILTER_FACTOR = 0.4f;

  private PriorityQueue<Map.Entry<String, Float>> sortedLabels =
      new PriorityQueue<>(
          RESULTS_TO_SHOW,
          new Comparator<Map.Entry<String, Float>>() {
            @Override
            public int compare(Map.Entry<String, Float> o1, Map.Entry<String, Float> o2) {
              return (o1.getValue()).compareTo(o2.getValue());
            }
          });


  ImageClassifier(Activity activity) throws IOException {
    tflite = new Interpreter(loadModelFile(activity));
    labelList = loadLabelList(activity);
    imgData =
        ByteBuffer.allocateDirect(
            4 * DIM_BATCH_SIZE * DIM_IMG_SIZE_X * DIM_IMG_SIZE_Y * DIM_PIXEL_SIZE);
    imgData.order(ByteOrder.nativeOrder());
    labelProbArray = new float[1][labelList.size()];
    filterLabelProbArray = new float[FILTER_STAGES][labelList.size()];
    Log.d(TAG, "Created a Tensorflow Lite Image Classifier.");
  }


  String classifyFrame(Bitmap bitmap) {
    if (tflite == null) {
      Log.e(TAG, "Image classifier has not been initialized; Skipped.");
      return "Uninitialized Classifier.";
    }
    convertBitmapToByteBuffer(bitmap);
    // Here's where the magic happens!!!
    long startTime = SystemClock.uptimeMillis();
    tflite.run(imgData, labelProbArray);
    long endTime = SystemClock.uptimeMillis();
    Log.d(TAG, "Timecost to run model inference: " + Long.toString(endTime - startTime));

    // smooth the results
    applyFilter();

    // print the results
    String textToShow = printTopKLabels();
    textToShow = Long.toString(endTime - startTime) + "ms" + textToShow;
    return textToShow;
  }

  void applyFilter(){
    int num_labels =  labelList.size();

    // Low pass filter `labelProbArray` into the first stage of the filter.
    for(int j=0; j<num_labels; ++j){
      filterLabelProbArray[0][j] += FILTER_FACTOR*(labelProbArray[0][j] -
                                                   filterLabelProbArray[0][j]);
    }
    // Low pass filter each stage into the next.
    for (int i=1; i<FILTER_STAGES; ++i){
      for(int j=0; j<num_labels; ++j){
        filterLabelProbArray[i][j] += FILTER_FACTOR*(
                filterLabelProbArray[i-1][j] -
                filterLabelProbArray[i][j]);

      }
    }

    // Copy the last stage filter output back to `labelProbArray`.
    for(int j=0; j<num_labels; ++j){
      labelProbArray[0][j] = filterLabelProbArray[FILTER_STAGES-1][j];
    }
  }

  /** Closes tflite to release resources. */
  public void close() {
    tflite.close();
    tflite = null;
  }

  /** Reads label list from Assets. */
  private List<String> loadLabelList(Activity activity) throws IOException {
    List<String> labelList = new ArrayList<String>();
    BufferedReader reader =
        new BufferedReader(new InputStreamReader(activity.getAssets().open(LABEL_PATH)));
    String line;
    while ((line = reader.readLine()) != null) {
      labelList.add(line);
    }
    reader.close();
    return labelList;
  }

  /** Memory-map the model file in Assets. */
  private MappedByteBuffer loadModelFile(Activity activity) throws IOException {
    AssetFileDescriptor fileDescriptor = activity.getAssets().openFd(MODEL_PATH);
    FileInputStream inputStream = new FileInputStream(fileDescriptor.getFileDescriptor());
    FileChannel fileChannel = inputStream.getChannel();
    long startOffset = fileDescriptor.getStartOffset();
    long declaredLength = fileDescriptor.getDeclaredLength();
    return fileChannel.map(FileChannel.MapMode.READ_ONLY, startOffset, declaredLength);
  }

  /** Writes Image data into a {@code ByteBuffer}. */
  private void convertBitmapToByteBuffer(Bitmap bitmap) {
    if (imgData == null) {
      return;
    }
    imgData.rewind();
    bitmap.getPixels(intValues, 0, bitmap.getWidth(), 0, 0, bitmap.getWidth(), bitmap.getHeight());
    // Convert the image to floating point.
    int pixel = 0;
    long startTime = SystemClock.uptimeMillis();
    for (int i = 0; i < DIM_IMG_SIZE_X; ++i) {
      for (int j = 0; j < DIM_IMG_SIZE_Y; ++j) {
        final int val = intValues[pixel++];
        imgData.putFloat((((val >> 16) & 0xFF)-IMAGE_MEAN)/IMAGE_STD);
        imgData.putFloat((((val >> 8) & 0xFF)-IMAGE_MEAN)/IMAGE_STD);
        imgData.putFloat((((val) & 0xFF)-IMAGE_MEAN)/IMAGE_STD);
      }
    }
    long endTime = SystemClock.uptimeMillis();
    Log.d(TAG, "Timecost to put values into ByteBuffer: " + Long.toString(endTime - startTime));
  }

  /** Prints top-K labels, to be shown in UI as the results. */
  private String printTopKLabels() {
    for (int i = 0; i < labelList.size(); ++i) {
      sortedLabels.add(
              new AbstractMap.SimpleEntry<>(labelList.get(i), labelProbArray[0][i]));
      if (sortedLabels.size() > RESULTS_TO_SHOW) {
        sortedLabels.poll();
      }

    }


    String textToShow = "";

   /* final int size = sortedLabels.size();
    for (int i = 0; i < size; ++i) {
*/


    Map.Entry<String, Float> label = sortedLabels.poll();

    //textToShow = String.format("\nHighest: %4.2f",labelProbArray[0][1]) + textToShow;
    textToShow = String.format("\nHighest: %4.2f", labelProbArray[0][1]) + textToShow;

    int list1 = 1;
    float f = labelProbArray[0][1];
    GlobalVars.reshigh = f;
    if (f > 0.95) {
      GlobalVars.scanresHigh = textToShow;
      GlobalVars.intentSet = true;
      textToShow = String.format("\nHighest: %4.2f %s ", labelProbArray[0][1], labelList.get(list1)) + textToShow;
      CameraActivity loadres = new CameraActivity();
      loadres.loadScanresults2();






    }

    return textToShow;


  }





  }

对于CameraFragment

/** Basic fragments for the Camera. */
public class Camera2BasicFragment extends Fragment
    implements FragmentCompat.OnRequestPermissionsResultCallback {



  /** Tag for the {@link Log}. */
  private static final String TAG = "TfLiteCameraDemo";

  private static final String FRAGMENT_DIALOG = "dialog";

  private static final String HANDLE_THREAD_NAME = "CameraBackground";

  private static final int PERMISSIONS_REQUEST_CODE = 1;

  private final Object lock = new Object();
  private boolean runClassifier = false;
  private boolean checkedPermissions = false;
  private TextView textView;
  private ImageClassifier classifier;

  /** Max preview width that is guaranteed by Camera2 API */
  private static final int MAX_PREVIEW_WIDTH = 1920;

  /** Max preview height that is guaranteed by Camera2 API */
  private static final int MAX_PREVIEW_HEIGHT = 1080;

  /**
   * {@link TextureView.SurfaceTextureListener} handles several lifecycle events on a {@link
   * TextureView}.
   */
  private final TextureView.SurfaceTextureListener surfaceTextureListener =
      new TextureView.SurfaceTextureListener() {

        @Override
        public void onSurfaceTextureAvailable(SurfaceTexture texture, int width, int height) {
          openCamera(width, height);
        }

        @Override
        public void onSurfaceTextureSizeChanged(SurfaceTexture texture, int width, int height) {
          configureTransform(width, height);
        }

        @Override
        public boolean onSurfaceTextureDestroyed(SurfaceTexture texture) {
          return true;
        }

        @Override
        public void onSurfaceTextureUpdated(SurfaceTexture texture) {}
      };

  /** ID of the current {@link CameraDevice}. */
  private String cameraId;


  private AutoFitTextureView textureView;

  private CameraCaptureSession captureSession;


  private CameraDevice cameraDevice;


  private Size previewSize;


  private final CameraDevice.StateCallback stateCallback =
      new CameraDevice.StateCallback() {

        @Override
        public void onOpened(@NonNull CameraDevice currentCameraDevice) {
          // This method is called when the camera is opened.  We start camera preview here.
          cameraOpenCloseLock.release();
          cameraDevice = currentCameraDevice;
          createCameraPreviewSession();
        }

        @Override
        public void onDisconnected(@NonNull CameraDevice currentCameraDevice) {
          cameraOpenCloseLock.release();
          currentCameraDevice.close();
          cameraDevice = null;
        }

        @Override
        public void onError(@NonNull CameraDevice currentCameraDevice, int error) {
          cameraOpenCloseLock.release();
          currentCameraDevice.close();
          cameraDevice = null;
          Activity activity = getActivity();
          if (null != activity) {
            activity.finish();
          }
        }
      };


  private HandlerThread backgroundThread;


  private Handler backgroundHandler;


  private ImageReader imageReader;


  private CaptureRequest.Builder previewRequestBuilder;


  private CaptureRequest previewRequest;


  private Semaphore cameraOpenCloseLock = new Semaphore(1);


  private CameraCaptureSession.CaptureCallback captureCallback =
      new CameraCaptureSession.CaptureCallback() {

        @Override
        public void onCaptureProgressed(
            @NonNull CameraCaptureSession session,
            @NonNull CaptureRequest request,
            @NonNull CaptureResult partialResult) {}

        @Override
        public void onCaptureCompleted(
            @NonNull CameraCaptureSession session,
            @NonNull CaptureRequest request,
            @NonNull TotalCaptureResult result) {}
      };


  private void showToast(final String text) {
    final Activity activity = getActivity();
    if (activity != null) {
      activity.runOnUiThread(
          new Runnable() {
            @Override
            public void run() {
              textView.setText(text);
            }
          });
    }
  }


  private static Size chooseOptimalSize(
      Size[] choices,
      int textureViewWidth,
      int textureViewHeight,
      int maxWidth,
      int maxHeight,
      Size aspectRatio) {

    // Collect the supported resolutions that are at least as big as the preview Surface
    List<Size> bigEnough = new ArrayList<>();
    // Collect the supported resolutions that are smaller than the preview Surface
    List<Size> notBigEnough = new ArrayList<>();
    int w = aspectRatio.getWidth();
    int h = aspectRatio.getHeight();
    for (Size option : choices) {
      if (option.getWidth() <= maxWidth
          && option.getHeight() <= maxHeight
          && option.getHeight() == option.getWidth() * h / w) {
        if (option.getWidth() >= textureViewWidth && option.getHeight() >= textureViewHeight) {
          bigEnough.add(option);
        } else {
          notBigEnough.add(option);
        }
      }
    }

    // Pick the smallest of those big enough. If there is no one big enough, pick the
    // largest of those not big enough.
    if (bigEnough.size() > 0) {
      return Collections.min(bigEnough, new CompareSizesByArea());
    } else if (notBigEnough.size() > 0) {
      return Collections.max(notBigEnough, new CompareSizesByArea());
    } else {
      Log.e(TAG, "Couldn't find any suitable preview size");
      return choices[0];
    }
  }

  public static Camera2BasicFragment newInstance() {
    return new Camera2BasicFragment();
  }


  @Override
  public View onCreateView(
      LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    return inflater.inflate(R.layout.fragment_camera2_basic, container, false);
  }

  /** Connect the buttons to their event handler. */
  @Override
  public void onViewCreated(final View view, Bundle savedInstanceState) {
    textureView = (AutoFitTextureView) view.findViewById(R.id.texture);
    textView = (TextView) view.findViewById(R.id.text);
  }


  @Override
  public void onActivityCreated(Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);
    try {
      classifier = new ImageClassifier(getActivity());
    } catch (IOException e) {
      Log.e(TAG, "Failed to initialize an image classifier.");
    }
    startBackgroundThread();
  }

  @Override
  public void onResume() {
    super.onResume();
    startBackgroundThread();


    if (textureView.isAvailable()) {
      openCamera(textureView.getWidth(), textureView.getHeight());
    } else {
      textureView.setSurfaceTextureListener(surfaceTextureListener);
    }
  }

  @Override
  public void onPause() {
    closeCamera();
    stopBackgroundThread();
    super.onPause();
  }

  @Override
  public void onDestroy() {
    classifier.close();
    super.onDestroy();
  }


  private void setUpCameraOutputs(int width, int height) {
    Activity activity = getActivity();
    CameraManager manager = (CameraManager) activity.getSystemService(Context.CAMERA_SERVICE);
    try {
      for (String cameraId : manager.getCameraIdList()) {
        CameraCharacteristics characteristics = manager.getCameraCharacteristics(cameraId);

        // We don't use a front facing camera in this sample.
        Integer facing = characteristics.get(CameraCharacteristics.LENS_FACING);
        if (facing != null && facing == CameraCharacteristics.LENS_FACING_FRONT) {
          continue;
        }

        StreamConfigurationMap map =
            characteristics.get(CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP);
        if (map == null) {
          continue;
        }


        Size largest =
            Collections.max(
                Arrays.asList(map.getOutputSizes(ImageFormat.JPEG)), new CompareSizesByArea());
        imageReader =
            ImageReader.newInstance(
                largest.getWidth(), largest.getHeight(), ImageFormat.JPEG, /*maxImages*/ 2);


        int displayRotation = activity.getWindowManager().getDefaultDisplay().getRotation();

        int sensorOrientation = characteristics.get(CameraCharacteristics.SENSOR_ORIENTATION);
        boolean swappedDimensions = false;
        switch (displayRotation) {
          case Surface.ROTATION_0:
          case Surface.ROTATION_180:
            if (sensorOrientation == 90 || sensorOrientation == 270) {
              swappedDimensions = true;
            }
            break;
          case Surface.ROTATION_90:
          case Surface.ROTATION_270:
            if (sensorOrientation == 0 || sensorOrientation == 180) {
              swappedDimensions = true;
            }
            break;
          default:
            Log.e(TAG, "Display rotation is invalid: " + displayRotation);
        }

        Point displaySize = new Point();
        activity.getWindowManager().getDefaultDisplay().getSize(displaySize);
        int rotatedPreviewWidth = width;
        int rotatedPreviewHeight = height;
        int maxPreviewWidth = displaySize.x;
        int maxPreviewHeight = displaySize.y;

        if (swappedDimensions) {
          rotatedPreviewWidth = height;
          rotatedPreviewHeight = width;
          maxPreviewWidth = displaySize.y;
          maxPreviewHeight = displaySize.x;
        }

        if (maxPreviewWidth > MAX_PREVIEW_WIDTH) {
          maxPreviewWidth = MAX_PREVIEW_WIDTH;
        }

        if (maxPreviewHeight > MAX_PREVIEW_HEIGHT) {
          maxPreviewHeight = MAX_PREVIEW_HEIGHT;
        }

        previewSize =
            chooseOptimalSize(
                map.getOutputSizes(SurfaceTexture.class),
                rotatedPreviewWidth,
                rotatedPreviewHeight,
                maxPreviewWidth,
                maxPreviewHeight,
                largest);

        // We fit the aspect ratio of TextureView to the size of preview we picked.
        int orientation = getResources().getConfiguration().orientation;
        if (orientation == Configuration.ORIENTATION_LANDSCAPE) {
          textureView.setAspectRatio(previewSize.getWidth(), previewSize.getHeight());
        } else {
          textureView.setAspectRatio(previewSize.getHeight(), previewSize.getWidth());
        }

        this.cameraId = cameraId;
        return;
      }
    } catch (CameraAccessException e) {
      e.printStackTrace();
    } catch (NullPointerException e) {
      // Currently an NPE is thrown when the Camera2API is used but not supported on the
      // device this code runs.
      ErrorDialog.newInstance(getString(R.string.camera_error))
          .show(getChildFragmentManager(), FRAGMENT_DIALOG);
    }
  }

  private String[] getRequiredPermissions() {
    Activity activity = getActivity();
    try {
      PackageInfo info =
          activity
              .getPackageManager()
              .getPackageInfo(activity.getPackageName(), PackageManager.GET_PERMISSIONS);
      String[] ps = info.requestedPermissions;
      if (ps != null && ps.length > 0) {
        return ps;
      } else {
        return new String[0];
      }
    } catch (Exception e) {
      return new String[0];
    }
  }

  /** Opens the camera specified by {@link Camera2BasicFragment#cameraId}. */
  private void openCamera(int width, int height) {
    if (!checkedPermissions && !allPermissionsGranted()) {
      FragmentCompat.requestPermissions(this, getRequiredPermissions(), PERMISSIONS_REQUEST_CODE);
      return;
    } else {
      checkedPermissions = true;
    }
    setUpCameraOutputs(width, height);
    configureTransform(width, height);
    Activity activity = getActivity();
    CameraManager manager = (CameraManager) activity.getSystemService(Context.CAMERA_SERVICE);
    try {
      if (!cameraOpenCloseLock.tryAcquire(2500, TimeUnit.MILLISECONDS)) {
        throw new RuntimeException("Time out waiting to lock camera opening.");
      }
      manager.openCamera(cameraId, stateCallback, backgroundHandler);
    } catch (CameraAccessException e) {
      e.printStackTrace();
    } catch (InterruptedException e) {
      throw new RuntimeException("Interrupted while trying to lock camera opening.", e);
    }
  }

  private boolean allPermissionsGranted() {
    for (String permission : getRequiredPermissions()) {
      if (ContextCompat.checkSelfPermission(getActivity(), permission)
          != PackageManager.PERMISSION_GRANTED) {
        return false;
      }
    }
    return true;
  }

  @Override
  public void onRequestPermissionsResult(
      int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
    super.onRequestPermissionsResult(requestCode, permissions, grantResults);
  }

  /** Closes the current {@link CameraDevice}. */
  private void closeCamera() {
    try {
      cameraOpenCloseLock.acquire();
      if (null != captureSession) {
        captureSession.close();
        captureSession = null;
      }
      if (null != cameraDevice) {
        cameraDevice.close();
        cameraDevice = null;
      }
      if (null != imageReader) {
        imageReader.close();
        imageReader = null;
      }
    } catch (InterruptedException e) {
      throw new RuntimeException("Interrupted while trying to lock camera closing.", e);
    } finally {
      cameraOpenCloseLock.release();
    }
  }

  /** Starts a background thread and its {@link Handler}. */
  private void startBackgroundThread() {
    backgroundThread = new HandlerThread(HANDLE_THREAD_NAME);
    backgroundThread.start();
    backgroundHandler = new Handler(backgroundThread.getLooper());
    synchronized (lock) {
      runClassifier = true;
    }
    backgroundHandler.post(periodicClassify);
  }

  /** Stops the background thread and its {@link Handler}. */
  private void stopBackgroundThread() {
    backgroundThread.quitSafely();
    try {
      backgroundThread.join();
      backgroundThread = null;
      backgroundHandler = null;
      synchronized (lock) {
        runClassifier = false;
      }
    } catch (InterruptedException e) {
      e.printStackTrace();
    }
  }

  /** Takes photos and classify them periodically. */
  private Runnable periodicClassify =
      new Runnable() {
        @Override
        public void run() {
          synchronized (lock) {
            if (runClassifier) {
              classifyFrame();
            }
          }
          backgroundHandler.post(periodicClassify);
        }
      };

  /** Creates a new {@link CameraCaptureSession} for camera preview. */
  private void createCameraPreviewSession() {
    try {
      SurfaceTexture texture = textureView.getSurfaceTexture();
      assert texture != null;

      // We configure the size of default buffer to be the size of camera preview we want.
      texture.setDefaultBufferSize(previewSize.getWidth(), previewSize.getHeight());

      // This is the output Surface we need to start preview.
      Surface surface = new Surface(texture);

      // We set up a CaptureRequest.Builder with the output Surface.
      previewRequestBuilder = cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
      previewRequestBuilder.addTarget(surface);

      // Here, we create a CameraCaptureSession for camera preview.
      cameraDevice.createCaptureSession(
          Arrays.asList(surface),
          new CameraCaptureSession.StateCallback() {

            @Override
            public void onConfigured(@NonNull CameraCaptureSession cameraCaptureSession) {
              // The camera is already closed
              if (null == cameraDevice) {
                return;
              }

              // When the session is ready, we start displaying the preview.
              captureSession = cameraCaptureSession;
              try {
                // Auto focus should be continuous for camera preview.
                previewRequestBuilder.set(
                    CaptureRequest.CONTROL_AF_MODE,
                    CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);

                // Finally, we start displaying the camera preview.
                previewRequest = previewRequestBuilder.build();
                captureSession.setRepeatingRequest(
                    previewRequest, captureCallback, backgroundHandler);
              } catch (CameraAccessException e) {
                e.printStackTrace();
              }
            }

            @Override
            public void onConfigureFailed(@NonNull CameraCaptureSession cameraCaptureSession) {
              showToast("Failed");
            }
          },
          null);
    } catch (CameraAccessException e) {
      e.printStackTrace();
    }
  }

  /**
   * Configures the necessary {@link android.graphics.Matrix} transformation to `textureView`. This
   * method should be called after the camera preview size is determined in setUpCameraOutputs and
   * also the size of `textureView` is fixed.
   *
   * @param viewWidth The width of `textureView`
   * @param viewHeight The height of `textureView`
   */
  private void configureTransform(int viewWidth, int viewHeight) {
    Activity activity = getActivity();
    if (null == textureView || null == previewSize || null == activity) {
      return;
    }
    int rotation = activity.getWindowManager().getDefaultDisplay().getRotation();
    Matrix matrix = new Matrix();
    RectF viewRect = new RectF(0, 0, viewWidth, viewHeight);
    RectF bufferRect = new RectF(0, 0, previewSize.getHeight(), previewSize.getWidth());
    float centerX = viewRect.centerX();
    float centerY = viewRect.centerY();
    if (Surface.ROTATION_90 == rotation || Surface.ROTATION_270 == rotation) {
      bufferRect.offset(centerX - bufferRect.centerX(), centerY - bufferRect.centerY());
      matrix.setRectToRect(viewRect, bufferRect, Matrix.ScaleToFit.FILL);
      float scale =
          Math.max(
              (float) viewHeight / previewSize.getHeight(),
              (float) viewWidth / previewSize.getWidth());
      matrix.postScale(scale, scale, centerX, centerY);
      matrix.postRotate(90 * (rotation - 2), centerX, centerY);
    } else if (Surface.ROTATION_180 == rotation) {
      matrix.postRotate(180, centerX, centerY);
    }
    textureView.setTransform(matrix);
  }

  /** Classifies a frame from the preview stream. */
  private void classifyFrame() {
    if (classifier == null || getActivity() == null || cameraDevice == null) {
      showToast("Uninitialized Classifier or invalid context.");
      return;
    }
    Bitmap bitmap =
        textureView.getBitmap(ImageClassifier.DIM_IMG_SIZE_X, ImageClassifier.DIM_IMG_SIZE_Y);
    String textToShow = classifier.classifyFrame(bitmap);
    bitmap.recycle();
    showToast(textToShow);
  }

  /** Compares two {@code Size}s based on their areas. */
  private static class CompareSizesByArea implements Comparator<Size> {

    @Override
    public int compare(Size lhs, Size rhs) {
      // We cast here to ensure the multiplications won't overflow
      return Long.signum(
          (long) lhs.getWidth() * lhs.getHeight() - (long) rhs.getWidth() * rhs.getHeight());
    }
  }

  /** Shows an error message dialog. */
  public static class ErrorDialog extends DialogFragment {

    private static final String ARG_MESSAGE = "message";

    public static ErrorDialog newInstance(String message) {
      ErrorDialog dialog = new ErrorDialog();
      Bundle args = new Bundle();
      args.putString(ARG_MESSAGE, message);
      dialog.setArguments(args);
      return dialog;
    }

    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
      final Activity activity = getActivity();
      return new AlertDialog.Builder(activity)
          .setMessage(getArguments().getString(ARG_MESSAGE))
          .setPositiveButton(
              android.R.string.ok,
              new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialogInterface, int i) {
                  activity.finish();
                }
              })
          .create();
    }
  }

}

这是我每次运行调试时遇到的错误

java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.content.Context.getPackageName()' on a null object reference
        at android.content.ContextWrapper.getPackageName(ContextWrapper.java:132)
        at android.content.ComponentName.<init>(ComponentName.java:128)
        at android.content.Intent.<init>(Intent.java:4868)
        at com.example.android.tflitecamerademo.loadScanresults.loadScanresults2(loadScanresults.java:11)
        at com.example.android.tflitecamerademo.ImageClassifier.printTopKLabels(ImageClassifier.java:246)
        at com.example.android.tflitecamerademo.ImageClassifier.classifyFrame(ImageClassifier.java:134)
        at com.example.android.tflitecamerademo.Camera2BasicFragment.classifyFrame(Camera2BasicFragment.java:663)
        at com.example.android.tflitecamerademo.Camera2BasicFragment.access$900(Camera2BasicFragment.java:69)
        at com.example.android.tflitecamerademo.Camera2BasicFragment$5.run(Camera2BasicFragment.java:558)
        at android.os.Handler.handleCallback(Handler.java:751)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:154)
        at android.os.HandlerThread.run(HandlerThread.java:61)

我做错了什么吗？谢谢大家

编辑:仍然有相同的错误

Answer 1

切勿像其他答案所建议的那样引用该 Activity

由于 GC 的工作方式，它只会导致内存泄漏。

您不应该直接实例化 Activity 。将其留给操作系统。 这就是你的 NPE

您的新 Activity 的上下文未初始化，因此导致此异常

您现在可能正在寻找的是:

public class ResultsActivity extends Activity {
    public static void launch(Context ctx, float data){
          Intent i = new Intent(ctx, ResultsActivity.class);
          i.putExtra("extraData", data);
          ctx.startActivity(i);
    }


   @Override
   public void onCreate(Bundle b){
          float data = getIntent().getExtra("extraData");
    }
}

假设您正在 Activity 中，请像这样使用它:

ResultsActivity.launch(this, yourValue);
//finish(); this Activity? Maybe?

如果您不参与其他 Activity ，则必须通过方法将上下文作为额外参数传递。

执行此操作的理想方法是将数据返回到触发“获取数据”的 Activity ，然后从那里启动新的 Activity

编辑

如果您使用的 UI 组件是 Fragment，请使用 onActivityCreated 生命周期。

public class SomeFragment extends Fragments {

    @Override
    public void onActivityCreated(Bundle b) {
        // And to get a reference of the context here you can do:
        Context ctx = getContext();
    }

    private void onFaceDetected(float probability) {
        Context ctx = getContext();
        ResultsActivity.launch(ctx, probability); // for instance
    }
}