setting locale to english on startup. keeping system locale for convertions like date format

Author: Death111

src/main/java/de/doubleslash/keeptime/App.java

@@ -21,6 +21,7 @@
 import java.io.StringWriter;
 import java.time.LocalDate;
 import java.util.List;
+import java.util.Locale;
 import java.util.Optional;
 import java.util.stream.Collectors;
 
@@ -84,6 +85,9 @@ public class App extends Application {
    @Override
    public void init() throws Exception {
       LOG.info("Starting KeepTime.");
+
+      setLocaleToEnglish();
+
       final DefaultExceptionHandler defaultExceptionHandler = new DefaultExceptionHandler();
       defaultExceptionHandler.register();
 
@@ -102,6 +106,22 @@ public void init() throws Exception {
       model.setSpringContext(springContext);
    }
 
+   private void setLocaleToEnglish() {
+      final Locale systemDefaultLocale = Locale.getDefault();
+      final Locale wantedApplicationLocale = Locale.ENGLISH;
+
+      if(systemDefaultLocale.getLanguage().equals(wantedApplicationLocale.getLanguage())){
+         LOG.debug("Application Locale already is '{}'. Nothing to do.", wantedApplicationLocale);
+         return;
+      }
+
+      LOG.info("Setting application Locale to '{}', was '{}'.", wantedApplicationLocale, systemDefaultLocale);
+      Locale.setDefault(wantedApplicationLocale);
+      Locale.setDefault(Locale.Category.DISPLAY, wantedApplicationLocale);
+      // keep system locale for format conversions (date, currency, numbers)
+      Locale.setDefault(Locale.Category.FORMAT, systemDefaultLocale);
+   }
+
    @Override
    public void start(final Stage primaryStage) {
       LOG.info("Initialising the UI");