java.lang.InstantiationException: класс com.example.camera.MainActivity не имеет конструктора без аргументов

Question

03-02 12:03:23.564: D/AndroidRuntime(9302): Shutting down VM 
 
03-02 12:03:23.570: E/AndroidRuntime(9302): FATAL EXCEPTION: main 
 
03-02 12:03:23.570: E/AndroidRuntime(9302): Process: com.example.camera, PID: 9302 
 
03-02 12:03:23.570: E/AndroidRuntime(9302): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.camera/com.example.camera.MainActivity}: java.lang.InstantiationException: class com.example.camera.MainActivity has no zero argument constructor 
 
03-02 12:03:23.570: E/AndroidRuntime(9302): \t at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2225) 
 
03-02 12:03:23.570: E/AndroidRuntime(9302): \t at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2388) 
 
03-02 12:03:23.570: E/AndroidRuntime(9302): \t at android.app.ActivityThread.access$800(ActivityThread.java:148) 
 
03-02 12:03:23.570: E/AndroidRuntime(9302): \t at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1292) 
 
03-02 12:03:23.570: E/AndroidRuntime(9302): \t at android.os.Handler.dispatchMessage(Handler.java:102) 
 
03-02 12:03:23.570: E/AndroidRuntime(9302): \t at android.os.Looper.loop(Looper.java:135) 
 
03-02 12:03:23.570: E/AndroidRuntime(9302): \t at android.app.ActivityThread.main(ActivityThread.java:5312) 
 
03-02 12:03:23.570: E/AndroidRuntime(9302): \t at java.lang.reflect.Method.invoke(Native Method) 
 
03-02 12:03:23.570: E/AndroidRuntime(9302): \t at java.lang.reflect.Method.invoke(Method.java:372) 
 
03-02 12:03:23.570: E/AndroidRuntime(9302): \t at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:901) 
 
03-02 12:03:23.570: E/AndroidRuntime(9302): \t at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:696) 
 
03-02 12:03:23.570: E/AndroidRuntime(9302): Caused by: java.lang.InstantiationException: class com.example.camera.MainActivity has no zero argument constructor 
 
03-02 12:03:23.570: E/AndroidRuntime(9302): \t at java.lang.Class.newInstance(Class.java:1563) 
 
03-02 12:03:23.570: E/AndroidRuntime(9302): \t at android.app.Instrumentation.newActivity(Instrumentation.java:1088) 
 
03-02 12:03:23.570: E/AndroidRuntime(9302): \t at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2215) 
 
03-02 12:03:23.570: E/AndroidRuntime(9302): \t ... 10 more 
 
03-02 12:03:23.570: E/AndroidRuntime(9302): Caused by: java.lang.NoSuchMethodException: <init> [] 
 
03-02 12:03:23.570: E/AndroidRuntime(9302): \t at java.lang.Class.getConstructor(Class.java:531) 
 
03-02 12:03:23.570: E/AndroidRuntime(9302): \t at java.lang.Class.getDeclaredConstructor(Class.java:510) 
 
03-02 12:03:23.570: E/AndroidRuntime(9302): \t at java.lang.Class.newInstance(Class.java:1561) 
 
03-02 12:03:23.570: E/AndroidRuntime(9302): \t ... 12 more

общественный класс MainActivity расширяет SurfaceView реализует SurfaceHolder.Callback, PreviewCallback {

SurfaceHolder mHolder; 
    Camera mCamera; 
//This variable is responsible for getting and setting the camera settings 
    private Parameters parameters; 
    //this variable stores the camera preview size 
    private Size previewSize; 
    //this array stores the pixels as hexadecimal pairs 
    private int[] pixels; 


    public MainActivity(Context context, Camera camera) { 
    super(context); 
    // TODO Auto-generated constructor stub 
    mCamera = camera; 
     // Install a SurfaceHolder.Callback so we get notified when the 
    // underlying surface is created and destroyed. 
    mHolder = getHolder(); 
    mHolder.addCallback(this); 
    mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS); 
    new MainActivity(){}; 
} 

    public MainActivity() { 
     // TODO Auto-generated constructor stub 
    } 

    public void surfaceCreated(SurfaceHolder holder) { 
     // The Surface has been created, acquire the camera and tell it where 
     // to draw. 
     if (mCamera != null) 
     { 
     mCamera = Camera.open(); 
     } 
     try { 
      mCamera.setPreviewDisplay(holder); 

      //sets the camera callback to be the one defined in this class 
      mCamera.setPreviewCallback(this); 
      mCamera.startPreview(); 
      ///initialize the variables 
      parameters = mCamera.getParameters(); 
      previewSize = parameters.getPreviewSize(); 
      pixels = new int[previewSize.width * previewSize.height]; 

     } catch (IOException exception) { 
      mCamera.release(); 
      mCamera = null; 
      // TODO: add more exception handling logic here 
     } 
    } 

    public void surfaceDestroyed(SurfaceHolder holder) { 
     // Surface will be destroyed when we return, so stop the preview. 
     // Because the CameraDevice object is not a shared resource, it's very 
     // important to release it when the activity is paused. 
     mCamera.stopPreview(); 
     mCamera.release(); 
     mCamera = null; 
    } 

    public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) { 
     // Now that the size is known, set up the camera parameters and begin 
     // the preview. 
     parameters.setPreviewSize(w, h); 
     //set the camera's settings 
     mCamera.setParameters(parameters); 
     mCamera.startPreview(); 
    } 

    @Override 
    public void onPreviewFrame(byte[] data, Camera camera) { 
     //transforms NV21 pixel data into RGB pixels 
     decodeYUV420SP(pixels, data, previewSize.width, previewSize.height); 
     //Outuput the value of the top left pixel in the preview to LogCat 
     Log.i("Pixels", "The top right pixel has the following RGB (hexadecimal) values:" 
       +Integer.toHexString(pixels[0]));  
    } 

    //Method from Ketai project! Not mine! See below... 
    void decodeYUV420SP(int[] rgb, byte[] yuv420sp, int width, int height) { 

      final int frameSize = width * height; 

      for (int j = 0, yp = 0; j < height; j++) {  int uvp = frameSize + (j >> 1) * width, u = 0, v = 0; 
       for (int i = 0; i < width; i++, yp++) { 
       int y = (0xff & ((int) yuv420sp[yp])) - 16; 
       if (y < 0) 
        y = 0; 
       if ((i & 1) == 0) { 
        v = (0xff & yuv420sp[uvp++]) - 128; 
        u = (0xff & yuv420sp[uvp++]) - 128; 
       } 

       int y1192 = 1192 * y; 
       int r = (y1192 + 1634 * v); 
       int g = (y1192 - 833 * v - 400 * u); 
       int b = (y1192 + 2066 * u); 

       if (r < 0)     r = 0;    else if (r > 262143) 
        r = 262143; 
       if (g < 0)     g = 0;    else if (g > 262143) 
        g = 262143; 
       if (b < 0)     b = 0;    else if (b > 262143) 
        b = 262143; 

       rgb[yp] = 0xff000000 | ((r << 6) & 0xff0000) | ((g >> 2) & 0xff00) | ((b >> 10) & 0xff); 
       } 
      } 
      } 
} 

При запуске этого кода я получил сообщение об ошибке java.lang.InstantiationException: class com.example.camera.MainActivity не имеет конструктора нулевых аргументов ...

Answer 1

Избавьтесь от своего MainActivity(Context context, Camera camera) конструктора. Никакой код никогда не будет использовать его. Переместите его код в другом месте.

Затем избавьтесь от своего конструктора MainActivity() и просто наследуйте конструктор суперкласса.

Answer 2

Я увеличил активность (просто старая активность), затем избавился от всех конструкторов, как указано выше. Это заставило его работать. В моем случае я вызывал активность из класса non-activity.