Flash切换按钮崩溃Android

应muku的要求。我自己回答。用于切换闪光灯

flashBtn.setonClickListener(new onClickListener(){    @Override    public onClick(View view)    {        if(cameraView!=null)//cameraView is the CameraPreview.class        { if(cameraView.isFlashOn() && isFlashRunning) { cameraView.FlashOff(camera);     isFlashRunning = false;        } else {     cameraView.FlashOn(camera);     isFlashRunning = true;   }    }});

FlashOn和FlashOff方法是

public void FlashOn(Camera mCamera) throws RemoteException    {// Get Camera Params for customisation        Camera.Parameters parameters = mCamera.getParameters();        // Check Whether device supports AutoFlash, If you YES then set        // AutoFlash        List<String> flashModes = parameters.getSupportedFlashModes();        if (flashModes.contains(android.hardware.Camera.Parameters.FLASH_MODE_TORCH))        { parameters.setFlashMode(Parameters.FLASH_MODE_TORCH); isFlashOn = true;        }        else if (flashModes.contains(Parameters.FLASH_MODE_ON))        { parameters.setFlashMode(Parameters.FLASH_MODE_ON); isFlashOn = true;        }        mCamera.setParameters(parameters);        mCamera.startPreview();        //mCamera.autoFocus(null);  // may be this is problem    }    public void FlashOff(Camera mCamera) throws RemoteException    {        // Get Camera Params for customisation        Camera.Parameters parameters = mCamera.getParameters();        // Check Whether device supports AutoFlash, If you YES then set        // AutoFlash        List<String> flashModes = parameters.getSupportedFlashModes();        if (flashModes.contains(android.hardware.Camera.Parameters.FLASH_MODE_OFF))        { parameters.setFlashMode(Parameters.FLASH_MODE_OFF); isFlashOn = false;        }        mCamera.setParameters(parameters);        mCamera.startPreview();    }