zbar条码扫描器中的一个片段

Question

I'm trying to get a barcode reader in a fragment but i'm receiving chrash. Does anybody has an idea about the problem? I'm new to fragments and don't know what I'm doing wrong. Please help..

LogCat:

08-02 09:48:22.890: E/AndroidRuntime(11718): FATAL EXCEPTION: main
08-02 09:48:22.890: E/AndroidRuntime(11718): java.lang.NullPointerException
08-02 09:48:22.890: E/AndroidRuntime(11718):    at com.learn2crack.tab.Android$2.onPreviewFrame(Android.java:106)
08-02 09:48:22.890: E/AndroidRuntime(11718):    at android.hardware.Camera$EventHandler.handleMessage(Camera.java:864)
08-02 09:48:22.890: E/AndroidRuntime(11718):    at android.os.Handler.dispatchMessage(Handler.java:99)
08-02 09:48:22.890: E/AndroidRuntime(11718):    at android.os.Looper.loop(Looper.java:176)
08-02 09:48:22.890: E/AndroidRuntime(11718):    at android.app.ActivityThread.main(ActivityThread.java:5365)
08-02 09:48:22.890: E/AndroidRuntime(11718):    at java.lang.reflect.Method.invokeNative(Native Method)
08-02 09:48:22.890: E/AndroidRuntime(11718):    at java.lang.reflect.Method.invoke(Method.java:511)
08-02 09:48:22.890: E/AndroidRuntime(11718):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1102)
08-02 09:48:22.890: E/AndroidRuntime(11718):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:869)
08-02 09:48:22.890: E/AndroidRuntime(11718):    at dalvik.system.NativeStart.main(Native Method)

and the code:

public class Android extends Fragment {

 public Android(){}

 private Camera mCamera;
 private CameraPreview mPreview;
 private Handler autoFocusHandler;
 private static final String TAG_PID = "pid";

 TextView scanText;
 ImageScanner scanner;
 private boolean barcodeScanned = false;
 private boolean previewing = true;
 FrameLayout preview;

 static {
     System.loadLibrary("iconv");
 }

    public void onCreate(Bundle savedInstanceState){
        super.onCreate(savedInstanceState);

    }

    @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                Bundle savedInstanceState) {

        View android = inflater.inflate(R.layout.android_frag, container, false);
        autoFocusHandler = new Handler();
        mCamera = getCameraInstance();
        mPreview = new CameraPreview(this.getActivity(), mCamera, previewCb, autoFocusCB);
        preview = (FrameLayout) android.findViewById(R.id.cameraPreview);
        preview.addView(mPreview);

        scanText = (TextView) android.findViewById(R.id.scanText);       

        return android;

    }


    public void onPause() {
        super.onPause();
        releaseCamera();
    }

    /** A safe way to get an instance of the Camera object. */
    public static Camera getCameraInstance(){
        Camera c = null;
        try {
            c = Camera.open();
        } catch (Exception e){
        }
        return c;
    }

    private void releaseCamera() {
        if (mCamera != null) {
            previewing = false;
            mCamera.setPreviewCallback(null);
            mCamera.release();
            mCamera = null;
        }
    }

    private Runnable doAutoFocus = new Runnable() {
            public void run() {
                if (previewing)
                    mCamera.autoFocus(autoFocusCB);
            }
        };

    PreviewCallback previewCb = new PreviewCallback() {
            public void onPreviewFrame(byte[] data, Camera camera) {
                Camera.Parameters parameters = camera.getParameters();
                Size size = parameters.getPreviewSize();

                Image barcode = new Image(size.width, size.height, "Y800");
                barcode.setData(data);

                int result = scanner.scanImage(barcode);

                if (result != 0) {
                    previewing = false;
                    mCamera.setPreviewCallback(null);
                    mCamera.stopPreview();

                    SymbolSet syms = scanner.getResults();
                    for (Symbol sym : syms) {
                        scanText.setText("barcode result " + sym.getData());
                        barcodeScanned = true;
                    }
                }
            }
        };

    // Mimic continuous auto-focusing
    AutoFocusCallback autoFocusCB = new AutoFocusCallback() {
            public void onAutoFocus(boolean success, Camera camera) {
                autoFocusHandler.postDelayed(doAutoFocus, 1000);
            }
        };

}

Answer 1

Try this..

You haven't initialize ImageScanner scanner like below

scanner = new ImageScanner();