Easist方式

开放应用程序级别构建。gradle并删除appcompact-v7的依赖和同步。 再次添加依赖项&同步。

错误了!

之前

后

出现这种情况的原因如下:

你没有安装SDK API(这是我的问题) 你的项目/Android Studio不知道需要的文件在哪里 您的项目引用了不支持AppCompatActivity的过时编译版本 有个错别字

可能的解决方式:

Check your .gradle file to make sure you’re not referencing an outdated version. AppCompatActivity was added in version 25.1.0 and belongs to Maven artifact com.android.support:appcompat-v7:28.0.0-alpha1, so do not use any version earlier than this. In your build.gradle (Module: app) file you should have the dependency listed: dependencies { compile 'com.android.support:appcompat-v7:25.1.0' } You may be using a different version, but just make sure you have listed the dependency. Open the SDK manager and download every API 7 or newer. If you were missing the needed API it will fix that issue, and downloading all the newer API’s can save you some hassle later on as well. Check for typos in your import statement. Make sure it doesn’t say “AppCompactActivity” instead of “AppCompatActivity”. Resync your project (File >Sync project with Gradle files) Rebuild your project (Build >rebuild) Clean your project (Build >clean project) Close and restart Android Studio Update Android Studio Regenerate your libraries folder – In Android Studio, view your files in project view. Find the folder YourProjectName >.idea >libraries. Rename the folder to “libraries_delete_me”. Close and reopen Android Studio. Open your project again and the libraries folder should be regenerated with all of the files; you can now delete the “libraries_delete_me” folder.

我把它修好了。gradle文件和appcompat依赖文件，比如编译'com.android.support:appcompat-v7:XX.X.X'

将其更改为编译'com.android.support:appcompat-v7:XX.X.+'

然后点击“同步”。如果代码中的其他内容都是正确的，那么所有的红色曲线都应该消失。

今天(4月22日)你可以使用新的AppCompatActivity和支持库v 22.1.0一起发布。

只需更改依赖项:

compile "com.android.support:appcompat-v7:22.1.0"

在这里你可以找到关于这个新类的更多信息。

如果其他方法都失败了，请确保添加了import语句。我已经删除了它，因为它显示错误，忘记把它添加回来，并尝试其他一切来修复:

进口android.support.v7.app.AppCompatActivity;

我把我的Gradle 2.3.3更新到4.4，在AppCompatActivity和Cardview上得到了一个错误。我尝试了清洁项目和重建项目。它不会工作，然后我去项目文件夹-> .idea ->创建备份库文件夹并删除它->，然后重建项目，解决了我的问题。