changes in locale does work when add many modules

Answer #1 100 %

Explanation

The problem is related to Appcompat. There are two different fixes depending on the version of AppCompat. Since you are using 1.2.0, you will have to implement that one.

AppCompatDelegateImpl ends up removing the locale, because essentially a ContextThemeWrapper wraps your ContextWrapper. See the implementation @ AppCompatDelegateImpl.java line 368 . Also lines 388, and 480.

try {
                ContextThemeWrapperCompatApi17Impl.applyOverrideConfiguration(
                        (android.view.ContextThemeWrapper) baseContext, config);
                return baseContext;
            } catch (IllegalStateException e) {
                if (DEBUG) {
                    Log.d(TAG, "Failed to apply configuration to base context", e);
                }
            }

The work-around for this is to over-ride getDelegate inside your Base Activity like this:

private var baseContextWrappingDelegate: AppCompatDelegate? = null

override fun getDelegate() = baseContextWrappingDelegate ?: BaseContextWrappingDelegate(super.getDelegate()).apply {
    baseContextWrappingDelegate = this
}

And you also need the following class ( see : Change Locale not work after migrate to Androidx ).

package androidx.appcompat.app

import android.content.Context
import android.content.res.Configuration
import android.os.Bundle
import android.util.AttributeSet
import android.view.MenuInflater
import android.view.View
import android.view.ViewGroup
import androidx.appcompat.view.ActionMode
import androidx.appcompat.widget.Toolbar

class BaseContextWrappingDelegate(private val superDelegate: AppCompatDelegate) : AppCompatDelegate() {

    override fun getSupportActionBar() = superDelegate.supportActionBar

    override fun setSupportActionBar(toolbar: Toolbar?) = superDelegate.setSupportActionBar(toolbar)

    override fun getMenuInflater(): MenuInflater? = superDelegate.menuInflater

    override fun onCreate(savedInstanceState: Bundle?) {
        superDelegate.onCreate(savedInstanceState)
        removeActivityDelegate(superDelegate)
        addActiveDelegate(this)
    }

    override fun onPostCreate(savedInstanceState: Bundle?) = superDelegate.onPostCreate(savedInstanceState)

    override fun onConfigurationChanged(newConfig: Configuration?) = superDelegate.onConfigurationChanged(newConfig)

    override fun onStart() = superDelegate.onStart()

    override fun onStop() = superDelegate.onStop()

    override fun onPostResume() = superDelegate.onPostResume()

    override fun setTheme(themeResId: Int) = superDelegate.setTheme(themeResId)

    override fun  findViewById(id: Int) = superDelegate.findViewById(id)

    override fun setContentView(v: View?) = superDelegate.setContentView(v)

    override fun setContentView(resId: Int) = superDelegate.setContentView(resId)

    override fun setContentView(v: View?, lp: ViewGroup.LayoutParams?) = superDelegate.setContentView(v, lp)

    override fun addContentView(v: View?, lp: ViewGroup.LayoutParams?) = superDelegate.addContentView(v, lp)

    override fun attachBaseContext2(context: Context) = wrap(superDelegate.attachBaseContext2(super.attachBaseContext2(context)))

    override fun setTitle(title: CharSequence?) = superDelegate.setTitle(title)

    override fun invalidateOptionsMenu() = superDelegate.invalidateOptionsMenu()

    override fun onDestroy() {
        superDelegate.onDestroy()
        removeActivityDelegate(this)
    }

    override fun getDrawerToggleDelegate() = superDelegate.drawerToggleDelegate

    override fun requestWindowFeature(featureId: Int) = superDelegate.requestWindowFeature(featureId)

    override fun hasWindowFeature(featureId: Int) = superDelegate.hasWindowFeature(featureId)

    override fun startSupportActionMode(callback: ActionMode.Callback) = superDelegate.startSupportActionMode(callback)

    override fun installViewFactory() = superDelegate.installViewFactory()

    override fun createView(parent: View?, name: String?, context: Context, attrs: AttributeSet): View? = superDelegate.createView(parent, name, context, attrs)

    override fun setHandleNativeActionModesEnabled(enabled: Boolean) {
        superDelegate.isHandleNativeActionModesEnabled = enabled
    }

    override fun isHandleNativeActionModesEnabled() = superDelegate.isHandleNativeActionModesEnabled

    override fun onSaveInstanceState(outState: Bundle?) = superDelegate.onSaveInstanceState(outState)

    override fun applyDayNight() = superDelegate.applyDayNight()

    override fun setLocalNightMode(mode: Int) {
        superDelegate.localNightMode = mode
    }

    override fun getLocalNightMode() = superDelegate.localNightMode

    private fun wrap(context: Context): Context {
        //Put wrapping implementation here
    }
}