无法解析符号“AppCompatActivity" [英] Cannot resolve symbol 'AppCompatActivity'

问题描述

我刚刚尝试使用 Android Studio.我创建了空白项目并尝试创建扩展 AppCompatActivity 的 Activity.不幸的是，Android Studio说"它

I've just tried to use Android Studio. I've created blank project and tried to create Activity which extends AppCompatActivity. Unfortunalty Android Studio "says" that it

无法解析符号AppCompatActivity"

Cannot resolve symbol 'AppCompatActivity'

我在我的app"模块的依赖列表中编译com.android.support:appcompat-v7:22.0.+"并多次重建项目.但是我只能使用 ActionBarActivity.我做错了什么?

I have compile "com.android.support:appcompat-v7:22.0.+" in dependency list of my "app" module and rebuilt project several times. However I can only use ActionBarActivity. What am I doing wrong?

推荐答案

这里对其他答案的一点补充，适用于在使用正确的 lib 版本和正确的类时遇到相同错误的任何人.

A little addition to other answers here, for anyone having the same error while using the right lib version and the right class.

当我升级到

appcompat-v7:22.1.0

其中 ActionBarActivity 已弃用且为空，AppCompatActivty 是要走的路，由于 Android Studio 中的一些故障，它并没有完全适应版本更改.

In which ActionBarActivity is deprecated and empty and AppCompatActivty is the way to go, due to some glitch in Android Studio, It didn't quite pick up on version change.

即即使 Gradle 运行没有错误，IDE 本身一直在说无法解析符号'AppCompatActivity'(并且它也无法通过Ctrl+N 搜索获得)

i.e. Even though Gradle ran without errors, the IDE itself kept saying Cannot resolve symbol 'AppCompatActivity' (and it also wasn't available through the Ctrl+N search)

我查看了 .idea/libraries 文件夹，发现没有适合新版本库的元文件.

I looked into the .idea/libraries folder and noticed there's no appropriate metafile for the new version of the lib.

因此，使用旧的可靠文件->无效缓存/重新启动就行了.当您觉得 Android Studio 有什么神奇的错误时，请务必尝试此操作.然后禁用离线模式和同步.

So, using the old-reliable File->Invalidate Caches/Restart did the trick. Always try this when you feel something is magically wrong with Android Studio. And then Disable offline mode and sync.

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