Demonstrate how settings can be persisted across sessions.

core/src/main/java/com/github/weisj/darklaf/settings/ThemeSettings.java

@@ -401,7 +401,12 @@ public class ThemeSettings implements ThemePreferenceListener {
 
     /** Saves the settings. */
     public void save() {
-        fetchFromSettingsPanel();
+        save(true);
+    }
+
+    /** Saves the settings. */
+    private void save(final boolean fetchFromPanel) {
+        if (fetchFromPanel) fetchFromSettingsPanel();
         LafManager.enabledPreferenceChangeReporting(currentConfiguration.isSystemPreferencesEnabled());
         savedConfiguration.load(currentConfiguration);
         LOGGER.fine(() -> "Saving settings " + savedConfiguration);
@@ -416,7 +421,7 @@ public class ThemeSettings implements ThemePreferenceListener {
     public void setConfiguration(final SettingsConfiguration configuration) {
         this.currentConfiguration.load(configuration);
         updateSettingsPanel();
-        save();
+        save(false);
     }
 
     /**

core/src/test/java/ui/PersistentThemeSettingsDemo.java

@@ -0,0 +1,76 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2020 Jannis Weis
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
+ * associated documentation files (the "Software"), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge, publish, distribute,
+ * sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all copies or
+ * substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
+ * NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+ * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ */
+package ui;
+
+import java.io.*;
+import java.util.prefs.Preferences;
+
+import javax.swing.*;
+
+import com.github.weisj.darklaf.settings.SettingsConfiguration;
+import com.github.weisj.darklaf.settings.ThemeSettings;
+
+public class PersistentThemeSettingsDemo {
+
+    public static void main(final String[] args) {
+        load();
+        Runtime.getRuntime().addShutdownHook(new Thread(PersistentThemeSettingsDemo::save));
+        SwingUtilities.invokeLater(() -> {
+            JFrame frame = new JFrame("Persistent Theme Demo");
+            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+            frame.setContentPane(new SettingsDemo().createComponent());
+            frame.pack();
+            frame.setLocationRelativeTo(null);
+            frame.setVisible(true);
+        });
+    }
+
+    private static void load() {
+        ThemeSettings settings = ThemeSettings.getInstance();
+        Preferences preferences = Preferences.userNodeForPackage(PersistentThemeSettingsDemo.class);
+        byte[] serializedSettings = preferences.getByteArray("themeSettings", null);
+        if (serializedSettings != null) {
+            try (ObjectInputStream in = new ObjectInputStream(new ByteArrayInputStream(serializedSettings))) {
+                SettingsConfiguration config = (SettingsConfiguration) in.readObject();
+                settings.setConfiguration(config);
+            } catch (IOException | ClassNotFoundException e) {
+                e.printStackTrace();
+            }
+        }
+        settings.apply();
+    }
+
+    private static void save() {
+        ThemeSettings settings = ThemeSettings.getInstance();
+        SettingsConfiguration config = settings.exportConfiguration();
+        ByteArrayOutputStream bos = new ByteArrayOutputStream();
+        try (ObjectOutputStream out = new ObjectOutputStream(bos)) {
+            out.writeObject(config);
+            out.flush();
+            Preferences preferences = Preferences.userNodeForPackage(PersistentThemeSettingsDemo.class);
+            preferences.putByteArray("themeSettings", bos.toByteArray());
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+
+}