Cannot resolve symbol android studio ошибка

You must have encountered the error “Cannot resolve symbol R” many times while building android projects. When you first create a new activity or new class, The R is red and Android Studio says it can’t recognize the symbol R. So you may hover over the R symbol, press Alt + Enter to import missing appropriate files. But doing so doesn’t fix this error. The letter R stands for the Resource. This error occurs because of the incapability of the build process to Sync Resource files with your projects. Usually, this happens because of the improper build of the project. 

Why There is a Need to fix “cannot resolve symbol R” in Android Studio?

The error “Cannot resolve symbol R”  in Android studio has faced mostly, when you shift your code to another Computer or send the code to another person. The “R” turns red and can’t run the Application and throw the error in “Logcat”. Most often “R cannot be resolved” error appears if there is an issue with some of your resource files. Due to this error, you are unable to build your application. That’s why we need to solve this error as it not getting away by just doing a simple restart or hitting Alt+Enter.

Now the point that comes here is how we can fix “cannot resolve symbol R” in Android Studio. So in this article, we are going to discuss six different methods to fix “cannot resolve symbol R” in Android Studio. 

Method 1

Try the sync Gradle. Just follow this path: File > Sync project with Gradle Files.

Method 2

Change Gradle version: Open your build.gradle file, search for gradle version and change the version. Say suppose you are using minSdkVersion 8 then change it to 9 and then build your project and also try to change buildToolsVersion. To change it follow this path: File > Project Structure > Modules.

After selecting the appropriate version click “OK“.

Method 3

Make sure your package name is correct in AndroidManifest.xml. Because sometimes, the R file is not generated because of package name in AndroidManifest does not match with the package module that you have. You might need to check  XML Files specifically if you have followed the correct syntax for ids. Then clean the project.

Method 4

Step 1: Clean the Project

To clean project: Click on Build > Clean project   

Step 2: Rebuild Project

Click on “Build” and click on “Rebuild Project”

Method 5

You may import com.example.your_project.R file in all your activities, do note that this file is not Android.R but your project R file. All you have to do is add this line to your activities import com.example.your_project.R.

Method 6

Try Invalidate caches and restart. Just click on Files from the top left and choose the “Invalidate Caches / Restart” option.

1. Class name

If you do misspell in the class name, the class won’t get imported properly, and the compiler won’t be able to find the class. These names are case sensitive and you must be specifically careful with them, or the class simply won’t get recognized by the compiler.

Another probability is that the class is not available in the current working directory. This happens after a renaming of package, so be sure that all the required imports got renamed, and check for if the CLASSPATH has ‘.’ ‘the current directory’ in it.

2. Variable name

If the issue is in a variable name, then most probably you did not declare your variable before you try to use it. This is also case sensitive, and so check for if you did misspell it.

Another chance is that the variable is written in the wrong scope. Like if you declare the variable in the method A and try to access it from method B. If you need to access the variable in both the methods, you should make it common to both by declaring it in the main method.

class A {
int a=5;
}
class B {
System.out.println(a); //a cannot be resolved
}
}

3. Methods

You might have given the method the wrong parameter datatypes, For example, calling an integer where you need a String value.

Another problem might be when you try to invoke a constructor that is not within the scope.

class A
{
private A(int a)
{
}
}

A a=new A(5); //this won’t work, unless you change the scope ‘private’ to ‘public’

A a=new A(“Hello world!”); //this won’t work, unless you change the Parameter type to String

This should be written like

class A
{
A(String a)
{
}
}

4. Missing resources R

All the files in the resources directory are assigned an integer value in a common class file called R.java, which is auto generated at build time. This acts as a pointer to all the files in the resources folder. The compiler during compilation simply checks for the R.java file and picks the correct resource from the resources directory using this R.java class file.

Once the compiler picks up the wrong value, it eventually misses the resource file and that is when missing R problem is notified. This happens if you accidentally delete the R.java file, or after a package rename if the CLASSPATH miss the ‘.current directory’.

When it comes to Android Studio or IntelliJ, a simple Invalidate and refresh of the IDE’s caches might address the problem.

• You can safely delete the ‘build’ folder that is in the app directory.
• Then File -> Invalidate Caches / Restart
• After the project is reloaded and indexed, do a clean and rebuild from the build menu, so that build folder will be regenerated and the missed Resources error is gone!

It will still show “cannot resolve R” error, only if you have performed refactoring the package name before. In such case, try importing the R by pressing ALT + ENTER simultaneously.

Not only you, but many programmers are also facing a “cannot resolve symbol r” error in Android app development. An “r” turns red and can’t run the Application and throw the error in “logcat”. This problem has faced mostly the time when you shift your code to another Computer or send the code to another person.

Where the letter R stands for the Resource. This error occurs because of the incapability of the build process to Sync Resource files with your projects. Usually, this happens because of the improper build of the project.

Solutions of Android resolve symbol r

There are many ways to remove error “cannot resolve symbol r“, Here are some:-

• XML File – there is a problem with your XML.
• Gradle Files – Not proper sync or different version.
• Caching –  Invalidate caches
• Package name – Changed the package name.
• Libraries/Modules – Downgrade some libraries which make resource conflict.
• Lowered compileSdkVersion and targetSdkVersion
• OLD Android Studio
• Clean and Rebuild Project

We will look at a solution for it one by one with a step. Chances are any one of them will solve it.

XML File

If your resource file XML file even minor miscoded then you will face this problem. Check your resource layout and other XML. Android Studio turns this file into a red color. Then check the file and code of it where is the problem.

The Gradle Files Sync

Try the sync Gradle, may this solve the “cannot resolve symbol android studio“. Follow this step:-

• Toolbar -> File -> Sync project with Gradle

• OR direct click on the icon -> Sync project with Gradle

Note: A Screenshot is from Mac OS, so there is a chances position of the button and icon change in Linux, Windows, and other os.

Still not working check the Gradle Version and update to the latest one.

Caching

It can be a problem of “cannot resolve symbol r android studio“, let try this also.

• File -> Invalidate caches and restart.

Package name

This is a very common mistake done by a developer changing a package name in manifest or change class location package. Let’s see if I change if the package in the AndroidManifest.xml.

Changing -> com.eyehunts.myapplication to com.eyehunts.a.myapplication

Output and code structures:

Libraries/Modules

A lower or upgrade version of any library can make generate this error. To prevent r error in android, check Module Grable and your project SDK and target version.

OLD Android Studio

Recently I face this cannot resolve symbol r issue, I tried all the ways mentioned in this tutorial. In the last, I did update my Android studio and the problem was solved.

You can check your Android studio version and update it:-

• Click -> Android Studio -> Check for updates …
• If update available -> Click -> Update & restart.
• If the delete old version option came after installation new patch, then do delete all. It’s just taking space in your computer hard disk.

Clean and Rebuild Project

Last but can be the first option to do solve error –can not resolve symbol r.

Almost everyone suggests this process. It may work if there is no package, version, Gradle version, SDK version, etc problem.

Let’s see step to do it:-

• Click on Build -> Clean project

• Click on “Build” and click on “Rebuild Project”

If still facing the issue – “How to solve cannot resolve symbol r in the Android Studio”, then comment below. And any other solution you have, then comment. We will update this tutorial.

Note: This example (Project) is developed in Android Studio 3.3.2. Tested on Android 9 ( Android-P), compile SDK version API 28: Android 9.0 (Pie)

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