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Code  ›  When using Camera TextureView , occur nullpointerExceptipn on android - Stack Overflow
https://stackoverflow.com/questions/45317574/when-using-camera-textureview-occur-nullpointerexceptipn-on-android
怕考试的柿子
1 年前
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Learn more about Teams when In my app clicked button start wifiapp 

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

At this time, call onSurfaceTextureDestroyed , onPause


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

and In wifiapp, click back button, restart my app.


at this time, call onSurfaceTextureAvailable 


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

When restart my app, occur NullPointerException

  
java.lang.NullPointerException: Attempt to invoke virtual method 'void
  android.hardware.Camera.setPreviewTexture(android.graphics.SurfaceTexture)'
  on a null object reference
        at kr.co.iosystem.blackeyeonandroid.video.CameraTextureView.onSurfaceTextureAvailable(CameraTextureView.java:82)
        at android.view.TextureView.getHardwareLayer(TextureView.java:368)
        at android.view.View.updateDisplayListIfDirty(View.java:15157)
        at android.view.View.draw(View.java:15954)
        at android.view.ViewGroup.drawChild(ViewGroup.java:3609)
        at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3399)
        at android.view.View.draw(View.java:16187)
        at android.view.View.updateDisplayListIfDirty(View.java:15180)
        at android.view.View.draw(View.java:15954)
        at android.view.ViewGroup.drawChild(ViewGroup.java:3609)
        at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3399)
        at android.view.View.updateDisplayListIfDirty(View.java:15175)
        at android.view.View.draw(View.java:15954)
        at android.view.ViewGroup.drawChild(ViewGroup.java:3609)
        at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3399)
        at android.view.View.draw(View.java:16187)
        at android.view.View.updateDisplayListIfDirty(View.java:15180)
        at android.view.View.draw(View.java:15954)
        at android.view.ViewGroup.drawChild(ViewGroup.java:3609)
        at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3399)
        at android.view.View.updateDisplayListIfDirty(View.java:15175)
        at android.view.View.draw(View.java:15954)
        at android.view.ViewGroup.drawChild(ViewGroup.java:3609)
        at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3399)
        at android.view.View.updateDisplayListIfDirty(View.java:15175)
        at android.view.View.draw(View.java:15954)
        at android.view.ViewGroup.drawChild(ViewGroup.java:3609)
        at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3399)
        at android.view.View.draw(View.java:16187)
        at com.android.internal.policy.PhoneWindow$DecorView.draw(PhoneWindow.java:2690)
        at android.view.View.updateDisplayListIfDirty(View.java:15180)
        at android.view.ThreadedRenderer.updateViewTreeDisplayList(ThreadedRenderer.java:282)
        at android.view.ThreadedRenderer.updateRootDisplayList(ThreadedRenderer.java:288)
        at android.view.ThreadedRenderer.draw(ThreadedRenderer.java:323)
        at android.view.ViewRootImpl.draw(ViewRootImpl.java:2609)
        at android.view.ViewRootImpl.performDraw(ViewRootImpl.java:2428)
        at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2061)
        at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1107)
        at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6007)
        at android.view.Choreographer$CallbackRecord.run(Choreographer.java:858)
        at android.view.Choreographer.doCallbacks(Choreographer.java:670)
        at android.view.Choreographer.doFrame(Choreographer.java:606)
        at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:844)
        at android.os.Handler.handleCallback(Handler.java:739)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:148)
        at android.app.ActivityThread.main(ActivityThread.java:5415)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:745)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:635)


I think occur NPE onSurfaceTextureDestroyed mCamera = null; .


because when my app restart, mCamera status is null call onSurfaceTextureAvailable , mCamera.setPreviewTexture(surfaceTexture) is null.


so I try delete mCamera = null


but occur diffrent error.

  
java.lang.RuntimeException: Camera is being used after
  Camera.release() was called
      at android.hardware.Camera.setPreviewTexture(Native Method)
      at kr.co.iosystem.blackeyeonandroid.video.CameraTextureView.onSurfaceTextureAvailable(CameraTextureView.java:82)
      at android.view.TextureView.getHardwareLayer(TextureView.java:368)
      at android.view.View.updateDisplayListIfDirty(View.java:15157)
      at android.view.View.draw(View.java:15954)
      at android.view.ViewGroup.drawChild(ViewGroup.java:3609)
      at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3399)
      at android.view.View.draw(View.java:16187)
      at android.view.View.updateDisplayListIfDirty(View.java:15180)
      at android.view.View.draw(View.java:15954)
      at android.view.ViewGroup.drawChild(ViewGroup.java:3609)
      at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3399)
      at android.view.View.updateDisplayListIfDirty(View.java:15175)
      at android.view.View.draw(View.java:15954)
      at android.view.ViewGroup.drawChild(ViewGroup.java:3609)
      at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3399)
      at android.view.View.draw(View.java:16187)
      at android.view.View.updateDisplayListIfDirty(View.java:15180)
      at android.view.View.draw(View.java:15954)
      at android.view.ViewGroup.drawChild(ViewGroup.java:3609)
      at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3399)
      at android.view.View.updateDisplayListIfDirty(View.java:15175)
      at android.view.View.draw(View.java:15954)
      at android.view.ViewGroup.drawChild(ViewGroup.java:3609)
      at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3399)
      at android.view.View.updateDisplayListIfDirty(View.java:15175)
      at android.view.View.draw(View.java:15954)
      at android.view.ViewGroup.drawChild(ViewGroup.java:3609)
      at android.view.ViewGroup.dispatchDraw(ViewGroup.java:3399)
      at android.view.View.draw(View.java:16187)
      at com.android.internal.policy.PhoneWindow$DecorView.draw(PhoneWindow.java:2690)
      at android.view.View.updateDisplayListIfDirty(View.java:15180)
      at android.view.ThreadedRenderer.updateViewTreeDisplayList(ThreadedRenderer.java:282)
      at android.view.ThreadedRenderer.updateRootDisplayList(ThreadedRenderer.java:288)
      at android.view.ThreadedRenderer.draw(ThreadedRenderer.java:323)
      at android.view.ViewRootImpl.draw(ViewRootImpl.java:2609)
      at android.view.ViewRootImpl.performDraw(ViewRootImpl.java:2428)
      at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2061)
      at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1107)
      at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6007)
      at android.view.Choreographer$CallbackRecord.run(Choreographer.java:858)
      at android.view.Choreographer.doCallbacks(Choreographer.java:670)
      at android.view.Choreographer.doFrame(Choreographer.java:606)
      at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:844)
      at android.os.Handler.handleCallback(Handler.java:739)
      at android.os.Handler.dispatchMessage(Handler.java:95)
      at android.os.Looper.loop(Looper.java:148)
      at android.app.ActivityThread.main(ActivityThread.java:5415)
      at java.lang.reflect.Method.invoke(Native Method)
      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:745)
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:635)


this error mCamera.setPrevieTexture(surfaceTexture)


How to solve this problem?


thanks.


full source


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;

if need more information. please comment.
thanks.!


Please check you class name and constructor name


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
        
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