Added advanced option to force English language

app/src/main/java/eu/faircode/email/ActivityBase.java

@@ -20,6 +20,7 @@ package eu.faircode.email;
 */
 
 import android.Manifest;
+import android.content.Context;
 import android.content.Intent;
 import android.content.SharedPreferences;
 import android.content.res.Configuration;
@@ -38,6 +39,11 @@ import androidx.preference.PreferenceManager;
 abstract class ActivityBase extends AppCompatActivity implements SharedPreferences.OnSharedPreferenceChangeListener {
     private boolean contacts;
 
+    @Override
+    protected void attachBaseContext(Context base) {
+        super.attachBaseContext(ApplicationEx.getLocalizedContext(base));
+    }
+
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         Log.i("Create " + this.getClass().getName() + " version=" + BuildConfig.VERSION_NAME);

app/src/main/java/eu/faircode/email/ApplicationEx.java

@@ -25,12 +25,15 @@ import android.app.NotificationChannel;
 import android.app.NotificationChannelGroup;
 import android.app.NotificationManager;
 import android.content.Context;
+import android.content.SharedPreferences;
+import android.content.res.Configuration;
 import android.media.Ringtone;
 import android.media.RingtoneManager;
 import android.net.Uri;
 import android.os.Build;
 import android.os.DeadSystemException;
 import android.os.RemoteException;
+import android.preference.PreferenceManager;
 import android.webkit.CookieManager;
 
 import org.json.JSONArray;
@@ -44,6 +47,7 @@ import java.util.Arrays;
 import java.util.Collections;
 import java.util.Date;
 import java.util.List;
+import java.util.Locale;
 
 import androidx.annotation.RequiresApi;
 
@@ -54,6 +58,11 @@ public class ApplicationEx extends Application {
             "service", "notification", "warning", "error"
     ));
 
+    @Override
+    protected void attachBaseContext(Context base) {
+        super.attachBaseContext(getLocalizedContext(base));
+    }
+
     @Override
     public void onCreate() {
         super.onCreate();
@@ -86,6 +95,18 @@ public class ApplicationEx extends Application {
         Core.init(this);
     }
 
+    static Context getLocalizedContext(Context context) {
+        SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
+        boolean english = prefs.getBoolean("english", false);
+
+        if (english) {
+            Configuration config = new Configuration(context.getResources().getConfiguration());
+            config.setLocale(Locale.US);
+            return context.createConfigurationContext(config);
+        } else
+            return context;
+    }
+
     private void createNotificationChannels() {
         if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.O) {
             NotificationManager nm = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);

app/src/main/java/eu/faircode/email/FragmentOptions.java

@@ -105,6 +105,7 @@ public class FragmentOptions extends FragmentBase implements SharedPreferences.O
     private SwitchCompat swLight;
     private Button btnSound;
 
+    private SwitchCompat swEnglish;
     private SwitchCompat swUpdates;
     private SwitchCompat swDebug;
 
@@ -182,6 +183,7 @@ public class FragmentOptions extends FragmentBase implements SharedPreferences.O
         swLight = view.findViewById(R.id.swLight);
         btnSound = view.findViewById(R.id.btnSound);
 
+        swEnglish = view.findViewById(R.id.swEnglish);
         swUpdates = view.findViewById(R.id.swUpdates);
         swDebug = view.findViewById(R.id.swDebug);
 
@@ -247,6 +249,18 @@ public class FragmentOptions extends FragmentBase implements SharedPreferences.O
             }
         });
 
+        swEnglish.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
+            @Override
+            public void onCheckedChanged(CompoundButton compoundButton, boolean checked) {
+                prefs.edit().putBoolean("english", checked).commit(); // apply won't work here
+
+                Intent intent = new Intent(getContext(), ActivityMain.class);
+                intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
+                startActivity(intent);
+                Runtime.getRuntime().exit(0);
+            }
+        });
+
         swUpdates.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
             @Override
             public void onCheckedChanged(CompoundButton compoundButton, boolean checked) {
@@ -634,6 +648,7 @@ public class FragmentOptions extends FragmentBase implements SharedPreferences.O
         swNotifyPreview.setEnabled(Helper.isPro(getContext()));
         swSearchLocal.setChecked(prefs.getBoolean("search_local", false));
         swLight.setChecked(prefs.getBoolean("light", false));
+        swEnglish.setChecked(prefs.getBoolean("english", false));
         swUpdates.setChecked(prefs.getBoolean("updates", true));
         swUpdates.setVisibility(Helper.isPlayStoreInstall(getContext()) ? View.GONE : View.VISIBLE);
         swDebug.setChecked(prefs.getBoolean("debug", false));