当扫描卡时，在Android设备上快速点击两次后退按钮时，card.io提供的演示应用程序崩溃了。这是a link！附件是logcat ....
11-27 13:53:59.149: D/AndroidRuntime(10401): Shutting down VM
11-27 13:53:59.149: W/dalvikvm(10401): threadid=1: thread exiting with uncaught exception (group=0x40a1d1f8)
11-27 13:53:59.149: E/AndroidRuntime(10401): FATAL EXCEPTION: main
11-27 13:53:59.149: E/AndroidRuntime(10401): java.lang.NullPointerException
11-27 13:53:59.149: E/AndroidRuntime(10401): at io.card.payment.CardIOActivity.onBackPressed(Unknown Source)
11-27 13:53:59.149: E/AndroidRuntime(10401): at android.app.Activity.onKeyUp(Activity.java:2099)
11-27 13:53:59.149: E/AndroidRuntime(10401): at android.view.KeyEvent.dispatch(KeyEvent.java:2575)
11-27 13:53:59.149: E/AndroidRuntime(10401): at android.app.Activity.dispatchKeyEvent(Activity.java:2329)
11-27 13:53:59.149: E/AndroidRuntime(10401): at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchKeyEvent(PhoneWindow.java:1806)
11-27 13:53:59.149: E/AndroidRuntime(10401): at android.view.ViewRootImpl.deliverKeyEventPostIme(ViewRootImpl.java:3327)
11-27 13:53:59.149: E/AndroidRuntime(10401): at android.view.ViewRootImpl.handleFinishedEvent(ViewRootImpl.java:3300)
11-27 13:53:59.149: E/AndroidRuntime(10401): at android.view.ViewRootImpl.handleMessage(ViewRootImpl.java:2460)
11-27 13:53:59.149: E/AndroidRuntime(10401): at android.os.Handler.dispatchMessage(Handler.java:99)
11-27 13:53:59.149: E/AndroidRuntime(10401): at android.os.Looper.loop(Looper.java:137)
11-27 13:53:59.149: E/AndroidRuntime(10401): at android.app.ActivityThread.main(ActivityThread.java:4424)
11-27 13:53:59.149: E/AndroidRuntime(10401): at java.lang.reflect.Method.invokeNative(Native Method)
11-27 13:53:59.149: E/AndroidRuntime(10401): at java.lang.reflect.Method.invoke(Method.java:511)
11-27 13:53:59.149: E/AndroidRuntime(10401): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:787)
11-27 13:53:59.149: E/AndroidRuntime(10401): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:554)
11-27 13:53:59.149: E/AndroidRuntime(10401): at dalvik.system.NativeStart.main(Native Method)
11-27 13:58:50.739: I/Process(10401): Sending signal. PID: 10401 SIG: 9
有人能为我提供解决方案吗？