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
如果你在.xml文件上有任何错误,无论你做什么,你都无法修复这个问题。我建议
-首先,检查XML文件以查找任何错误和
-秒查找事件日志什么Android工作室捕捉到的错误,它会告诉你哪个文件和错误在哪里。
这就是我解决R问题的方法
其他回答
在xml文件中简单地定义一个应用程序名称空间就会导致这种情况。这是一个完全无害的行,只选择了一个符号(从许多符号中)来解析。简单地删除整行,在下面的图片中灰色,使我的代码引用未解析的符号。甚至当我添加回线,它决定没有问题。图。
我认为如果你把活动文件放到另一个文件夹而不是默认文件夹。你需要导入com.example.yourproject.R(这是你的项目R文件而不是Android。例如,在MainActivity文件中插入这一行:
import com.example.yourproject.R;
我确实做了一个项目,而且成功了 但在此之前,请尝试检查清单中的包名称,重新构建并清理项目。如果问题没有解决,那就放弃你的项目
我已经做了其他答案中提到的所有步骤,但它仍然没有得到解决。我正在使用android工作室花栗鼠,最后我能够通过删除来解决这个问题
maven { url "https://jitpack.io" }
从设置。gradle我在回答这个问题,我认为这样做可能会帮助到一些人
最近,当我更新一个项目的很多库时,我就遇到了这种情况。没有找到R,但是我可以很好地构建和运行项目。它没有崩溃。IDE只是在所有地方显示红色。
我试过
Check for damaged/improper XMLs and images, none found Check for invalid resource file names (e.g. capitalized), none found Downgrade some libraries because maybe it was a resource conflict, not resolved Lowered compileSdkVersion and targetSdkVersion because, in the past, I encountered resource issues due to this. In this project however, that was not the case. Clean, didn't help Rebuild project, didn't help Invalidate caches/Restart multiple times, didn't help Adjusted idea.max.intellisense.filesize to a very high value, didn't help Did a Lint run, no errors found
最后,我发现降级我的Gradle构建工具(从3.3.1到3.2.1)解决了这个问题。这是我唯一要做的改变。其余内容已更新。现在,我所有的库都更新了,没有问题。
buildscript {
repositories {
google()
jcenter()
}
dependencies {
//classpath 'com.android.tools.build:gradle:3.3.1'
classpath 'com.android.tools.build:gradle:3.2.1'
classpath 'com.google.gms:google-services:4.2.0'
// NOTE: Do not place your application dependencies here; they belong
// in the individual module build.gradle files
}
}
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