您好，我想在没有活动扩展的情况下在班上加载其他活动，因此我使用了另一个具有活动的班级，这是我的 MAINACTIVITY
的代码
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;
}
}
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都会得到的错误
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)
编辑：它仍然有相同的错误
答案 0 :(得分：0)
由于GC的工作方式，这只会导致内存泄漏。
您应该不直接实例化活动。留给操作系统。 这就是您的NPE的原因
您的新活动的上下文未初始化，因此导致此异常
您现在可能正在寻找的东西是这样的：
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");
}
}
假设您处于活动状态，请像这样使用它：
ResultsActivity.launch(this, yourValue);
//finish(); this Activity? Maybe?
如果您不参加其他活动，则必须通过方法将上下文作为附加参数传递。
执行此操作的理想方法是将数据返回到触发“获取数据”的活动，然后从那里开始新的活动
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
}
}