Issue #506: Available languages must be hard-coded

Don't have the language list in the properties, but rather in code. Also
add a localized version of the language name to the dropdown list.

Author: Bananeweizen

net.sf.eclipsecs.ui/src/net/sf/eclipsecs/ui/Messages.java

@@ -176,8 +176,6 @@ public final class Messages extends NLS {
 
   public static String CheckstylePreferencePage_lblLocaleLanguage;
 
-  public static String CheckstylePreferencePage_lblLocaleLanguages;
-
   public static String CheckstylePreferencePage_version;
 
   public static String CheckstylePropertyPage_btnActivateCheckstyle;

net.sf.eclipsecs.ui/src/net/sf/eclipsecs/ui/messages.properties

@@ -62,7 +62,6 @@ CheckstylePreferencePage_lblIncludeModuleIds=Include module id (if available) in
 CheckstylePreferencePage_lblIncludeRulenames = Include rule names in violation messages
 CheckstylePreferencePage_lblLimitMarker = Limit Checkstyle markers per resource to
 CheckstylePreferencePage_lblLocaleLanguage= Rule message language
-CheckstylePreferencePage_lblLocaleLanguages= default,de,en,es,fi,fr,ja,pt,tr,zh
 CheckstylePreferencePage_lblProjectUsage = Used in projects:
 CheckstylePreferencePage_lblRebuild = Rebuild projects if needed:
 CheckstylePreferencePage_lblWarnFilesets = Warn before losing configured file sets

net.sf.eclipsecs.ui/src/net/sf/eclipsecs/ui/preferences/CheckstylePreferencePage.java

@@ -20,7 +20,12 @@
 
 package net.sf.eclipsecs.ui.preferences;
 
+import java.util.Arrays;
 import java.util.Collection;
+import java.util.List;
+import java.util.Locale;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
 
 import org.eclipse.core.resources.IProject;
 import org.eclipse.jface.dialogs.IDialogConstants;
@@ -79,6 +84,15 @@
  */
 public class CheckstylePreferencePage extends PreferencePage implements IWorkbenchPreferencePage {
 
+  private static final String DEFAULT_LANGUAGE = "default";
+
+  private static final List<String> SUPPORTED_LANGUAGES = Stream.concat(
+          Stream.of(DEFAULT_LANGUAGE),
+          Arrays.stream("de,en,es,fi,fr,ja,pt,tr,zh"
+          .split(","))
+          .sorted())
+          .collect(Collectors.toList());
+
   private final PageController mController = new PageController();
 
   private final ICheckConfigurationWorkingSet mWorkingSet;
@@ -201,9 +215,15 @@ private Composite createGeneralContents(Composite parent) {
     final Label lblLanguage = new Label(langComposite, SWT.NULL);
     lblLanguage.setText(Messages.CheckstylePreferencePage_lblLocaleLanguage);
     mLanguageIf = new Combo(langComposite, SWT.READ_ONLY);
-    mLanguageIf.setItems(Messages.CheckstylePreferencePage_lblLocaleLanguages.split("[, ;]+"));
+    mLanguageIf.setItems(SUPPORTED_LANGUAGES.stream().map(code -> {
+      if (code == DEFAULT_LANGUAGE) {
+        return code;
+      }
+      var loc = Locale.forLanguageTag(code);
+      return code + " - " + loc.getDisplayLanguage(loc);
+    }).toArray(String[]::new));
     final String lang = CheckstylePluginPrefs.getString(CheckstylePluginPrefs.PREF_LOCALE_LANGUAGE);
-    final int selectedLang = mLanguageIf.indexOf(lang == null || lang.isEmpty() ? "default" : lang);
+    final int selectedLang = SUPPORTED_LANGUAGES.indexOf(lang == null || lang.isEmpty() ? DEFAULT_LANGUAGE : lang);
     if (selectedLang != -1) {
       mLanguageIf.select(selectedLang);
     }
@@ -376,7 +396,7 @@ public boolean performOk() {
       mWorkingSet.store();
 
       CheckstylePluginPrefs.setString(CheckstylePluginPrefs.PREF_LOCALE_LANGUAGE,
-              mLanguageIf.getItem(mLanguageIf.getSelectionIndex()));
+              SUPPORTED_LANGUAGES.get(mLanguageIf.getSelectionIndex()));
 
       //
       // Save the general preferences.