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这是我的代码的一部分，用于一个简单的 android 相机应用程序，

public class CameraView extends Activity implements Callback, OnClickListener {


static final int FOTO_MODE = 0;
private static final String TAG = "CameraTest";
Camera mCamera;
boolean mPreviewRunning = false;
private Context mContext = this;

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

    Log.e(TAG, "onCreate");

    Bundle extras = getIntent().getExtras();

    getWindow().setFormat(PixelFormat.TRANSLUCENT);
    requestWindowFeature(Window.FEATURE_NO_TITLE);
    getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
            WindowManager.LayoutParams.FLAG_FULLSCREEN);
    setContentView(R.layout.main);
    mSurfaceView = (SurfaceView) findViewById(R.id.surface_camera);
    mSurfaceView.setOnClickListener(this);
    mSurfaceHolder = mSurfaceView.getHolder();
    mSurfaceHolder.addCallback(this);
    mSurfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}

@Override
protected void onRestoreInstanceState(Bundle savedInstanceState) {
    super.onRestoreInstanceState(savedInstanceState);
}

Camera.PictureCallback mPictureCallback = new Camera.PictureCallback() {
    public void onPictureTaken(byte[] imageData, Camera c) {

        if (imageData != null) {

            Intent mIntent = new Intent();

            StoreByteImage(mContext, imageData, 50,
                    "ImageName");
            mCamera.startPreview();

            setResult(FOTO_MODE, mIntent);
            finish();

        }
    }
};







public void onClick(View arg0) {

    mCamera.takePicture(null, mPictureCallback, mPictureCallback);

}

但是当我运行程序时，它在以下行中给出了空指针异常

mSurfaceView.setOnClickListener(this);

我不明白这个问题。你们能澄清一下吗？

4

2 回答 2

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mSurfaceView = (SurfaceView) findViewById(R.id.surface_camera);

正在返回 null。空指针异常是因为您尝试访问的指针为空。

在此处查看 findViewById API

于 2012-04-18T20:23:54.037 回答
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这NullPointerException意味着 mSurfaceView 是null.

在添加之前尝试添加此代码OnClickListener：

if (null == mSurfaceView)
  Log.e(TAG, "mSurfaceView is NULL!");
else
  Log.e(TAG, 'mSurfaceView IS OKAY!");
于 2012-04-18T20:23:01.187 回答