使用Camera TextureView时，在android上出现nullpointerExceptipn

Question

我的应用程序相机预览使用textureview。

现在的情况是，在我的应用程序中单击按钮启动wifiapp

Intent intent = getPackageManager().getLaunchIntentForPackage("kr.co.aaa.wifiapp");
startActivity(intent);

@Override
public boolean onSurfaceTextureDestroyed(SurfaceTexture surfaceTexture) {
    mCamera.setPreviewCallback(null);
    mCamera.release();
    mCamera = null;
}

此时，调用OnSurfaceTextureAvailable

@Override
public void onSurfaceTextureAvailable(SurfaceTexture surfaceTexture, int width, int height) {
  try {  
       mCamera.setPreviewTexture(surfaceTexture);  //NPE
       mCamera.startPreview();
  } catch (IOException e) {
      e.printStackTrace();
  }
}

重新启动我的应用程序时，发生NullPointerException

我认为出现NPEonSurfaceTextureDestromedmcamera=null；。

因为当我的应用程序重新启动时，mCamera状态为null调用OnSurfaceTextureAvailable，mCamera.SetPreviewTexture（surfaceTexture）为null。

所以我尝试删除mcamera=null

但会出现不同的错误。

此错误Mcamera.SetPrevietExture（surfaceTexture）

如何解决这个问题？

多谢了。

public class CameraTexture extends TextureView implement TextureView.SurfaceTextureListener {
  private Camera mCamera;
  private TextureView mTextureView;

  public CameraTexture(Context context, LiveCamera liveCamera) {
    super(context);

    mCamera = liveCamera.camera;

    mTextureVeiw = (TextureView) activity.findViewById(R.id.live);
    mTextureView.setSurfaceTextureListener(this);
 }

 @Override 
 public void onSurfaceTextureAvailable(SurfaceTexture surfaceTexture, int width, int height) {

   try {
      mCamera.setPreviewTexture(surfaceTexture);
      mCamera.startPreview();
   } catch (IOException e) {
      e.printStackTrace();
   } 
 }

 @Override 
 public void onSurfaceTextureSizeChanged(SurfaceTexture surfaceTexture, int i, int i2) {
 }

 @Override
 public boolean onSurfaceTextureDestroyed(SurfaceTexture surfaceTexture) {
       mCamera.setPreviewCallback(null);
       mCamera.release();
       mCamera = null; // if delete this line, occur Camera is being used after Camera.release() was called  error
 }

 @Override
 public void onSurfaceTextureUpdated(SurfaceTexture surfaceTexture) {
    Bitmap bitmap = mTextureView.getBitmap();

    int width = bitmap.getWidth();
    int height = bitmap.getHeight();

    int[] pixels = new int[bitmap.getHeight() * bitmap.getWidth()];
    bitmap.getPixels(pixels, 0, width, 0, 0, width, height);
 }
 }


public class LiveCamera {
   public Camera camera;
}

Answer 1

请检查类名和构造函数名

public class CameraTexture extends TextureView implement TextureView.SurfaceTextureListener {
  private Camera mCamera;
  private TextureView mTextureView;

  public CameraTexture(Context context, LiveCamera liveCamera) {
    super(context);

    mCamera = liveCamera.camera;

    mTextureVeiw = (TextureView) activity.findViewById(R.id.live);
    mTextureView.setSurfaceTextureListener(this);
 }

//your remain code

}