Gradle buildConfigField BuildConfig cannot resolve symbol

I am using Gradle to build my Android application. I am trying to use some flags based on the build type (release or debug).

My Gradle file looks like this:

android {
    buildTypes {
        debug {
            buildConfigField 'boolean', 'PREPROD', 'true'
            buildConfigField 'boolean', 'STAGING', 'false'
        }

        release {
            buildConfigField 'boolean', 'PREPROD', 'false'
            buildConfigField 'boolean', 'STAGING', 'false'
        }
    }
}

And if I try to call BuildConfig.PREPROD or BuildConfig.STAGING I get a "Cannot resolve symbol" error. The Gradle sync was successful, so I don't know if I forgot some steps in order to be able to use this feature?

The generated BuildConfig.java file is the following (in build/source/buildConfig/debug/com.example.myapp):

package com.example.myapp;

public final class BuildConfig {
  public static final boolean DEBUG = Boolean.parseBoolean("true");
  public static final String PACKAGE_NAME = "com.example.myapp";
  public static final String BUILD_TYPE = "debug";
  public static final String FLAVOR = "";
  public static final int VERSION_CODE = 400;
  public static final String VERSION_NAME = "";
}

Make sure your file is importing the right BuildConfig class. Sometimes if you have other project libraries or modules, it may import the wrong buildConfig. Make sure your import it's like this com.project.app.BuildConfig. I was Having the same issue and the problem was this, Hope it can help somebody.

I was getting the same bug. Try to click on synchronize, on the right side of save. Do that after gradle sync.

Changes in gradle build files don't refresh the generation of the BuildConfig class, even if you click the yellow "sync now" bar at the top. A full clean will force generating this file.

In Android Studio: Build -> Clean Project

Happened to me because I did not declared a String field properly.

I forgot the escaping characters. Changing from :

buildConfigField "String", "FOO", "foo"

to

buildConfigField "String", "FOO", "\"foo\""

solved the problem.

In my case, in Android Studio:

1. Build -> Clean Project;

2. File -> Invalidate Caches / Restart...

3. Build -> Rebuild Project