setting look and feel automatically

src/me/teridax/jcash/Main.java

@@ -40,11 +40,42 @@ public final class Main {
 
         Locales.autodetectDefaultLocale();
 
+        setPlatformDependingTheme();
+
         // create main instance and show the login screen
         instance();
         getInstance().showLoginScreen();
     }
 
+    private static void setPlatformDependingTheme() {
+        // default look and feel
+        var laf = UIManager.getCrossPlatformLookAndFeelClassName();
+
+        // runtime os
+        String os = System.getProperty("os.name").toLowerCase();
+        LOGGER.fine("Detected operating system: " + os);
+
+        // set look and feel class name depending on the platform we run on
+        if (os.contains("win") || os.contains("mac")) {
+            LOGGER.info("Detected Windows or MacOS based operating system, using system look and feel");
+            laf = UIManager.getSystemLookAndFeelClassName();
+        } else if (os.contains("nix") || os.contains("nux") || os.contains("aix") || os.contains("sunos")) {
+            LOGGER.info("Detected Unix/Linux based operating system, using GTK look and feel");
+            laf = "com.sun.java.swing.plaf.gtk.GTKLookAndFeel";
+        } else {
+            LOGGER.warning("Unable to detect operating system: " + os);
+        }
+
+        try {
+            LOGGER.info("Setting look and feel to class: " + laf);
+            UIManager.setLookAndFeel(laf);
+        } catch (ClassNotFoundException | UnsupportedLookAndFeelException e) {
+            LOGGER.severe("Look and feel class not found: " + e.getMessage());
+        } catch (InstantiationException | IllegalAccessException e) {
+            LOGGER.warning("Could not set look and feel: " + e.getMessage());
+        }
+    }
+
     /**
      * Get the main singleton instance of this program
      * @return the singleton instance of this class

src/me/teridax/jcash/gui/Loader.java

@@ -8,6 +8,7 @@ import javax.swing.*;
 import javax.swing.filechooser.FileNameExtensionFilter;
 
 import static javax.swing.JFileChooser.APPROVE_OPTION;
+import static me.teridax.jcash.lang.Translator.translate;
 
 /**
  * Utility class for loading a BMS configuration from a csv file.
@@ -17,7 +18,7 @@ public class Loader {
     /**
      * Filter that only allows for files with *.csv extension
      */
-    private static final FileNameExtensionFilter FILE_FILTER = new FileNameExtensionFilter("Comma separated value spreadsheet", "csv", "CSV");
+    private static final FileNameExtensionFilter FILE_FILTER = new FileNameExtensionFilter(translate("Comma separated value spreadsheet"), "csv", "CSV");
 
     private Loader() {}
 
@@ -35,7 +36,7 @@ public class Loader {
         fileChooser.setDialogType(JFileChooser.OPEN_DIALOG);
         fileChooser.setAcceptAllFileFilterUsed(false);
 
-        if (fileChooser.showDialog(null, Translator.translate("Load database")) == APPROVE_OPTION) {
+        if (fileChooser.showDialog(null, translate("Load database")) == APPROVE_OPTION) {
             // parse file content
             try {
                 return BankingManagementSystem.loadFromCsv(fileChooser.getSelectedFile().toPath());

src/me/teridax/jcash/lang/languages.csv

@@ -46,3 +46,4 @@ Address,Adresse,Dirección,Adresse,地址
 Account,Konto,Cuenta,Compte,账户
 Closing JCash,JCash wird geschlossen,JCash está cerrado,JCash est fermé,JCash 已关闭
 you're logged out,Du bist abgemeldet,Ha cerrado la sesión,Tu es déconnecté,您已注销
+Comma separated value spreadsheet,Tabelle mit kommagetrennten Werten,Planilla de valores separados por comas,Feuille de calcul à valeurs séparées par des virgules,逗号分隔值电子表格