“无法解析符号R”在Android Studio

In every instance in all of my classes where I reference R.id.something, the R is in red and it says "cannot resolve symbol R". Also every time there is R.layout.something it is underlined in red and says "cannot resolve method setContentView(?)". The project always builds fine. It is annoying to see this all the time. I have read many other questions on here about something similar but most involved importing projects from Eclipse. I am using what I believe to be the most recent version of Android Studio and the project was created with Android Studio and worked without any "cannot resolve R" problems. I would like to know what causes this if anyone knows.

当前回答

我也遇到了这个问题，我用这种方法解决了它。首先进入Gradle，点击clean。其次，单击Build。

确保不要从android studio清洁

2018-10-14 15:34:36

其他回答

在OS X和Android Studio 0.2.13上，我在com上做了“跳转到声明”。<项目>。在我的活动之一。当我回到活动文件时，所有的警告都消失了。

编辑:在此工作之前，您需要构建当前的构建变体。

2013-10-14 23:28:33

我按照上面的方法做了，但不管用。在我的例子中，当我在Android-L预览中每个Java函数都显示为红色时，我不得不设置JDK……

在Mac:

Click once on what is Red (or underlined) in your code (i.e. Activity, String). Click on the Red Light Bulb Point that appears on the left. Select "Setup JDK". Verify if annotations.jar and android.jar are in the current SDK version you are using (my case SDK 20 Android-L). You should also have the "res" folder, but I somehow still had it in the settings. If not, select the SDK and press "-". Then press "+" and locate the SDK folder on your computer (Mac: Applications > Android Studio.app > sdk). Select the version of the SDK you require (in my case 20 Android-L). Press Add. Build and Sync.

然后一切都恢复了正常。

2014-07-07 15:12:46

类型1:关闭项目并删除项目中的.gradle文件然后重建项目类型2:如果类型1不起作用，那就把它拿回来 project9Zip文件)，然后删除项目。然后提取压缩项目，只是导入提取的项目，它将工作很好，因为这对我很管用。

2019-03-13 05:40:13

在我的情况下:res/someLayout.xml文件出错，然后我解决它。然后清除该项目。错误消失了。

2015-12-25 16:23:42

你的代码被打乱了。答案相当简单。

点击构建->清洁项目。

这样应该可以了。

检查你的Android Studio版本。

我目前使用的是Android Studio 3.0.1。

2017-12-21 09:01:50