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): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2225)
03-02 12:03:23.570: E/AndroidRuntime(9302): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2388)
03-02 12:03:23.570: E/AndroidRuntime(9302): at android.app.ActivityThread.access$800(ActivityThread.java:148)
03-02 12:03:23.570: E/AndroidRuntime(9302): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1292)
03-02 12:03:23.570: E/AndroidRuntime(9302): at android.os.Handler.dispatchMessage(Handler.java:102)
03-02 12:03:23.570: E/AndroidRuntime(9302): at android.os.Looper.loop(Looper.java:135)
03-02 12:03:23.570: E/AndroidRuntime(9302): at android.app.ActivityThread.main(ActivityThread.java:5312)
03-02 12:03:23.570: E/AndroidRuntime(9302): at java.lang.reflect.Method.invoke(Native Method)
03-02 12:03:23.570: E/AndroidRuntime(9302): at java.lang.reflect.Method.invoke(Method.java:372)
03-02 12:03:23.570: E/AndroidRuntime(9302): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:901)
03-02 12:03:23.570: E/AndroidRuntime(9302): 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): at java.lang.Class.newInstance(Class.java:1563)
03-02 12:03:23.570: E/AndroidRuntime(9302): at android.app.Instrumentation.newActivity(Instrumentation.java:1088)
03-02 12:03:23.570: E/AndroidRuntime(9302): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2215)
03-02 12:03:23.570: E/AndroidRuntime(9302): ... 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): at java.lang.Class.getConstructor(Class.java:531)
03-02 12:03:23.570: E/AndroidRuntime(9302): at java.lang.Class.getDeclaredConstructor(Class.java:510)
03-02 12:03:23.570: E/AndroidRuntime(9302): at java.lang.Class.newInstance(Class.java:1561)
03-02 12:03:23.570: E/AndroidRuntime(9302): ... 12 more
公共类MainActivity扩展SurfaceView实现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);
}
}
}
}
在运行此代码时，我收到一条错误，指出java.lang.InstantiationException：class com.example.camera.MainActivity没有零参数构造函数...
答案 0 :(得分：2)
摆脱你的MainActivity(Context context, Camera camera)构造函数。没有代码会使用它。将代码移到其他地方。
然后，摆脱你的MainActivity()构造函数，继承超类'构造函数。
答案 1 :(得分：1)
我扩展了Activity（只是普通的旧Activity）然后摆脱了如上所述的所有构造函数。这使它成功了。就我而言，我正在从非活动类中调用一个活动。