BuildConfig.DEBUG always false when building library projects with gradle

With Android Studio 1.1 and having also the gradle version at 1.1 it is possible:

Library

android {
    publishNonDefault true
}

App

dependencies {
    releaseCompile project(path: ':library', configuration: 'release')
    debugCompile project(path: ':library', configuration: 'debug')
}

Complete documentation can be found here http://tools.android.com/tech-docs/new-build-system/user-guide#TOC-Library-Publication

EDIT:

The issue has just been marked as fixed for the Android Studio Gradle Version 3.0. There you can just use implementation project(path: ':library') and it'll select the correct configuration automatically.

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This is expected behavior for this.

Library projects only publish their release variants for consumption by other projects or modules.

We're working at fixing this but this is non trivial and requires a significant amount of work.

You can track the issue at https://code.google.com/p/android/issues/detail?id=52962

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Check for imports, sometimes BuildConfig is imported from any class of library unintentionally. For example:

import io.fabric.sdk.android.BuildConfig;

In this case BuildConfig.DEBUG will always return false;

import com.yourpackagename.BuildConfig;

In this case BuildConfig.DEBUG will return your real build variant.

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This is like Phil's answer except it doesn't need the context:

private static Boolean sDebug;

/**
 * Is {@link BuildConfig#DEBUG} still broken for library projects? If so, use this.</p>
 * 
 * See: https://code.google.com/p/android/issues/detail?id=52962</p>
 * 
 * @return {@code true} if this is a debug build, {@code false} if it is a production build.
 */
public static boolean isDebugBuild() {
    if (sDebug == null) {
        try {
            final Class<?> activityThread = Class.forName("android.app.ActivityThread");
            final Method currentPackage = activityThread.getMethod("currentPackageName");
            final String packageName = (String) currentPackage.invoke(null, (Object[]) null);
            final Class<?> buildConfig = Class.forName(packageName + ".BuildConfig");
            final Field DEBUG = buildConfig.getField("DEBUG");
            DEBUG.setAccessible(true);
            sDebug = DEBUG.getBoolean(null);
        } catch (final Throwable t) {
            final String message = t.getMessage();
            if (message != null && message.contains("BuildConfig")) {
                // Proguard obfuscated build. Most likely a production build.
                sDebug = false;
            } else {
                sDebug = BuildConfig.DEBUG;
            }
        }
    }
    return sDebug;
}

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As a workaround, you can use this method, which uses reflection to get the field value from the app (not the library):

/**
 * Gets a field from the project's BuildConfig. This is useful when, for example, flavors
 * are used at the project level to set custom fields.
 * @param context       Used to find the correct file
 * @param fieldName     The name of the field-to-access
 * @return              The value of the field, or {@code null} if the field is not found.
 */
public static Object getBuildConfigValue(Context context, String fieldName) {
    try {
        Class<?> clazz = Class.forName(context.getPackageName() + ".BuildConfig");
        Field field = clazz.getField(fieldName);
        return field.get(null);
    } catch (ClassNotFoundException e) {
        e.printStackTrace();
    } catch (NoSuchFieldException e) {
        e.printStackTrace();
    } catch (IllegalAccessException e) {
        e.printStackTrace();
    }
    return null;
}

To get the DEBUG field, for example, just call this from your Activity:

boolean debug = (Boolean) getBuildConfigValue(this, "DEBUG");

I have also shared this solution on the AOSP Issue Tracker.

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Not really the correct way to check if you are in debug flavor, but you can check if the app itself is debuggable via:

private static Boolean sIsDebuggable;

public static boolean isDebuggable(Context context) {
    if (sIsDebuggable == null)
        sIsDebuggable = (context.getApplicationInfo().flags & ApplicationInfo.FLAG_DEBUGGABLE) != 0;
    return sIsDebuggable;
}

The default behavior of apps and libraries will match it perfectly.

If you need a better workaround, you can use this instead:

public static boolean isInDebugFlavour(Context context) {
    if (sDebugFlavour == null) {
        try {
            final String packageName = context.getPackageName();
            final Class<?> buildConfig = Class.forName(packageName + ".BuildConfig");
            final Field DEBUG = buildConfig.getField("DEBUG");
            DEBUG.setAccessible(true);
            sDebugFlavour = DEBUG.getBoolean(null);
        } catch (final Throwable t) {
            sDebugFlavour = false;
        }
    }
    return sDebugFlavour;
}

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You can create your own BuildConfig class for each build type using gradle

public class MyBuildConfig
{
    public static final boolean DEBUG = true;
}

for /src/debug/.../MyBuildConfig.java and...

public class MyBuildConfig
{
    public static final boolean DEBUG = false;
}

for /src/release/.../MyBuildConfig.java

Then use:

if (MyBuildConfig.DEBUG)
    Log.d(TAG, "Hey! This is debug version!");

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Here is another solution.

1) Create an interface

public interface BuildVariantDetector {

    boolean isDebugVariant();

}

2) Use this interface on Application class (Appplication module)

public class MyApplication extends Application implements BuildVariantDetector {

    @Override
    public boolean isDebugVariant() {
        return BuildConfig.DEBUG; //application (main module) Buildonfig
    }

}

3) And then in library module:

boolean debugVariant = ((BuildVariantDetector)getApplication()).isDebugVariant();

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We had the same problem. I came up with something like this:

We have a SDK (library) and a demo project, hierarchy looks like this:

Parent
  |
  + SDK (:SDK)
  |
  + DemoApp (:DemoApp)

For the demo app we have, were :SDK:jarjarDebug and :SDK:jarjarRelease are some specific tasks for :SDK that produce some post-processed jars:

dependencies {
    debugCompile tasks.getByPath(":SDK:jarjarDebug").outputs.files
    releaseCompile tasks.getByPath(":SDK:jarjarRelease").outputs.files
    ... more dependencies ...
}

This works even for multiple buildTypes built at once. Debugging is a bit difficult though. Please comment.

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In my case I was importing the wrong BuildConfig as my project has many library modules. The fix was to import the correct BuildConfig for my app module.

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This is my workaround: reflect BuildConfig of app module:

`public static boolean debug = isDebug();

private static boolean isDebug() {
    boolean result = false;
    try {
        Class c = Class.forName("com.example.app.BuildConfig");
        Field f = c.getField("DEBUG");
        f.setAccessible(true);
        result = f.getBoolean(c);
    } catch (ClassNotFoundException e) {
        e.printStackTrace();
    } catch (NoSuchFieldException e) {
        e.printStackTrace();
    } catch (IllegalAccessException e) {
        e.printStackTrace();
    }
    return result;
}`

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You could try this on each of the projects buildTypes:

parent.allprojects.each{ project -> android.defaultConfig.debuggable = true}

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Working with debuggable true in gradle file.

buildTypes {
  demo{
 debuggable true
    }
  live{
 debuggable true
    }
}

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BuildConfig.DEBUG is not reliable at all, Android has provided an internal flag that is globally available indicating if a build is in Debug or non-Debug mode

(getContext().getApplicationInfo().flags &ApplicationInfo.FLAG_DEBUGGABLE) != 0) 

will be true if it is in debug

Credits : https://medium.com/@elye.project/checking-debug-build-the-right-way-d12da1098120

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