Question

我在关于Camera对象为空的crashlytics上收到大量崩溃报告。在测试和使用应用程序时，它不会发生在我身上。

Fatal Exception: java.lang.RuntimeException: Unable to resume activity {packageName/activityName}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.hardware.Camera$Parameters android.hardware.Camera.getParameters()' on a null object reference
   at android.app.ActivityThread.performResumeActivity(ActivityThread.java:3026)
   at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:3057)
   at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2396)
   at android.app.ActivityThread.access$800(ActivityThread.java:151)
   at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1309)
   at android.os.Handler.dispatchMessage(Handler.java:102)
   at android.os.Looper.loop(Looper.java:135)
   at android.app.ActivityThread.main(ActivityThread.java:5349)
   at java.lang.reflect.Method.invoke(Method.java)
   at java.lang.reflect.Method.invoke(Method.java:372)
   at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:908)
   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:703)

Caused by java.lang.NullPointerException: Attempt to invoke virtual method 'android.hardware.Camera$Parameters android.hardware.Camera.getParameters()' on a null object reference
   at activityName.o(SourceFile:612)
   at activityName.u(SourceFile:772)
   at activityName.onResume(SourceFile:539)
   at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1241)
   at android.app.Activity.performResume(Activity.java:6106)
   at android.app.ActivityThread.performResumeActivity(ActivityThread.java:3015)
   at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:3057)
   at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2396)
   at android.app.ActivityThread.access$800(ActivityThread.java:151)
   at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1309)
   at android.os.Handler.dispatchMessage(Handler.java:102)
   at android.os.Looper.loop(Looper.java:135)
   at android.app.ActivityThread.main(ActivityThread.java:5349)
   at java.lang.reflect.Method.invoke(Method.java)
   at java.lang.reflect.Method.invoke(Method.java:372)
   at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:908)
   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:703)

崩溃发生在camera.getParameters()。

所以它基本上是因为相机由于某种原因暂时无法连接？

是否与您在手机上的相机应用中遇到的"Can't connect to camera."错误类似？

希望有人可以对此有所了解并分享一些方法来解决这个问题。

Answer 1

1）您是否正在初始化相机？

 camera = camera.open();

2）您是否使用过相机权限？

 <uses-permission android:name="android.permission.CAMERA"/>

3）确保在立即打开相机后不要这样做：

camera  = null;

4）尝试在manifest.xml中明确地以纵向模式设置相机的方向

5）如果您使用的是Marshmellow，则需要运行时权限才能访问相机。

Answer 2

我有同样的问题。如果您将相机用于活动或碎片状态，则应释放它。就我而言，我没有在onDestroy函数上添加“ mCamera.stopPreview（）;和mCamera.release（）”。

https://developer.android.com/training/camera/cameradirect#java

@Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        // Surface will be destroyed when we return, so stop the preview.
        if (mCamera != null) {
            // Call stopPreview() to stop updating the preview surface.
            mCamera.stopPreview();
        }
    }

    /**
     * When this function returns, mCamera will be null.
     */
    private void stopPreviewAndFreeCamera() {

        if (mCamera != null) {
            // Call stopPreview() to stop updating the preview surface.
            mCamera.stopPreview();

            // Important: Call release() to release the camera for use by other
            // applications. Applications should release the camera immediately
            // during onPause() and re-open() it during onResume()).
            mCamera.release();

            mCamera = null;
        }
    }

Camera.open有时会返回null

2 个答案: