Why does showing a Toast outside of onCreate() crash my application?

Question

old question: "Why does creating a Toast crash my application?"

My application runs fine if I don't use toasts but if I want to create and show a simple Toast like this:

   Toast SimpleToast = Toast.makeText(getApplicationContext(), "Just a toast.",Toast.LENGTH_LONG);
   SimpleToast.setGravity(Gravity.TOP, 0, 0);
   SimpleToast.show();

I get these lines in the log and then the app crashes:

NotificationService   enqueueToast pkg=games.MyAppName callback=android.app.ITransientNotification$Stub$Proxy@49603368 duration=1
ResourceType          No package identifier when getting name for resource number 0x00000000
AndroidRuntime        Shutting down VM
dalvikvm              threadid=3: thread exiting with uncaught exception (group=0x4001b188)
AndroidRuntime        Uncaught handler: thread main exiting due to uncaught exception
AndroidRuntime        java.lang.NullPointerException

I've checked and double checked the code above is what makes it crash. I'm running on the emulator as I currently don't have an android phone.

Answer 1

It seems that you have tried to dereference a Null pointer somewhere, try stepping in the debugger and see where exactly. It could be the .setGravity call. That would indicate that Toast.makeText has failed to create your toast. You should note that toasts can be created and displayed from an Activity or Service.

Answer 2

Wrap the code in a try-catch and check the stack trace on the Exception that's thrown. It sounds like a callback method on an Activity is being called when you weren't expecting it to.

Answer 3

To the best of my knowledge, you can't show a toast with an application context, you have to show it with an Activity context. The toast isn't bound to your app, it's bound to the activity that you're showing it on. Instead of using getApplicationContext(), try using a variable named ctx containing a reference to your activity.

Good luck!

Answer 4

For some reason, getApplicationContext returns null. Try "ActivityName.this" instead, on your onClick() method, inside the Listener.