Android Studio无法解析符号

Question

I'm just starting with programming Android apps and was working through the developers guide on android.com. When trying to display a text on a second activity it says it cannot resolve the symbol EXTRA_MESSAGE as you can see here:

As far as I can tell I did every step like the guide says. I also tried copy and pasting everything but it still doesn't work. What am I missing?

Answer 1

You're doing a static import of extra message from some random class in MainActivity. That's wrong, don't do that. Define EXTRA_MESSAGE as a public final static String, with whatever value you want (I'd suggest "message") in your MainActivity.

Answer 2

There is two ways of solving it.

1) Use same static variable (Its a dirty way). At DisplayMessageActivity use android.provider.AlarmClock.EXTRA_MESSAGE .

2) This approach I recommend you. Create public static final String field at MainActivity , remove android.provider.AlarmClock.EXTRA_MESSAGE , and use MainAcitivity field at both classes. Content of this variable does not matter as long as it is unique extra key.