android studio找不到“活动”符号

Question

I have tried to create and run hello world new app using Android studio. however i cannot compile as it says it's cannot resolve Activity symbol.

and also other basic symbols in the black template.

I suggest adding/configuration the JDK.

I guess I'm doing this wrong, because I have tried to add the JDK and the problem re-occurred.

how to solve this?

UPDATE1

couldn't find external build

Android studio 0.2.6

Answer 1

Android Studio

File -> Invalidate Caches / Restart

It Worked for me.

Answer 2

确保导入 android.app.Activity。

import android.app.Activity;

Answer 3

I ran into this problem as well and it was driving me crazy. Here is what worked for me:

I noticed that Under File|Project Structure the Classpath for my selected android SDK (Android 4.3 Google APIs) was blank.

I changed the Build target to a different SDK, then switched back and the Classpath tab became properly populated. Once I did that, android symbols were resolved in my project.

If you don't see pathtosdk/android-##/android.jar listed in the classpath, this could be your solution.

Answer 4

As addition, if all solutions you have tried getting no result, in my case, make sure your activity already defined on AndroidManifest.xml .

<activity
   android:name=".Main2Activity"
   ...
></activity>

This happens when I create activity manually by creating Activity Class directly without building from template (right click -> new -> activity -> Empty Activity/other templates ) .

Answer 5

我在文件 -> 项目结构中更改了我的模块版本，更改为我下载的最新版本