Android Studio“无法解析符号R"，但项目会编译并运行 [英] Android Studio “cannot resolve symbol R” but project compiles and runs

问题描述

Android Studio在所有Java文件中以红色显示:无法解析符号R"，但项目可以编译并运行.

Android Studio displays in all java files in red : "cannot resolve symbol R" but the project compiles and runs.

我在这里尝试了所有解决方案: Android Studio无法解析符号"但是项目可以编译并正常运行，但是运气不好.

I have tried every solution here: Android Studio "cannot resolve symbol" but project compiles and works, but with no luck.

我试图:

• 使缓存无效并重新启动android studio

• invalidate caches and restart android studio

删除.gradle和.idea文件夹

delete .gradle and .idea folders

清理并重建项目

安装新版本的android studio

install a new version of android studio

遇到gradle文件，然后撤消更改并同步项目

mess up with gradle file then undo changes and sync project

我想尝试的一件事，但我不知道如何实现，是在我第一次打开该项目时从头开始重新打开该项目，但我不知道如何执行此操作.

One thing that I want to try, but I don't know how to achieve, is to reopen the project from scratch as I was opening it for the first time, but I don't know how to do this.

我也从这里尝试了答案: Android Studio表示无法解析符号"但是项目可以编译， 但还是没有运气.

I also tried answers from here: Android Studio says "cannot resolve symbol" but project compiles, but again with no luck.

Android Studio版本= 3.2.1

Android studio version = 3.2.1

依赖版本:

classpath 'com.android.tools.build:gradle:3.4.0-alpha01'
classpath 'com.google.gms:google-services:4.0.0'

推荐答案

由于某些原因，我不明白，

For some reason that i do not understand ,

构建版本的这种组合导致了问题:

this combination of build versions made the issue :

grade version = 4.10.1

classpath 'com.android.tools.build:gradle:3.4.0-alpha01'

当我切换到这些构建版本时:

when i switched to these build versions :

grade version = 4.6

classpath 'com.android.tools.build:gradle:3.2.1'

问题已解决！

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