Make some classes sealed / final

Author: NichtStudioCode

invui/src/main/java/xyz/xenondevs/invui/InvUI.java

@@ -15,15 +15,14 @@
 /**
  * Main class of InvUI, managing the plugin instance.
  */
-public class InvUI implements Listener {
+public final class InvUI implements Listener {
 
     private static final InvUI INSTANCE = new InvUI();
 
     private final List<Runnable> disableHandlers = new ArrayList<>();
     private @Nullable Plugin plugin;
 
-    private InvUI() {
-    }
+    private InvUI() {}
 
     /**
      * Returns the singleton instance of InvUI.

invui/src/main/java/xyz/xenondevs/invui/gui/AbstractIngredientMapper.java

@@ -4,7 +4,7 @@
 import java.util.function.Supplier;
 
 @SuppressWarnings("unchecked")
-abstract class AbstractIngredientMapper<S extends AbstractIngredientMapper<S>> implements IngredientMapper<S> {
+abstract sealed class AbstractIngredientMapper<S extends AbstractIngredientMapper<S>> implements IngredientMapper<S> permits IngredientPreset.Builder, Structure {
 
     /**
      * Maps ingredient keys ({@link Character characters}) to their corresponding {@link Ingredient} instances.

invui/src/main/java/xyz/xenondevs/invui/gui/IngredientMapper.java

@@ -14,7 +14,7 @@
  *
  * @param <S> The type of the {@link IngredientMapper}
  */
-public interface IngredientMapper<S extends IngredientMapper<S>> extends Cloneable {
+public sealed interface IngredientMapper<S extends IngredientMapper<S>> extends Cloneable permits AbstractIngredientMapper, Gui.Builder {
 
     /**
      * Applies the given {@link IngredientPreset} to this {@link IngredientMapper}.

invui/src/main/java/xyz/xenondevs/invui/gui/IngredientPreset.java

@@ -5,7 +5,7 @@
 /**
  * A predefined set of ingredients that can be used in {@link Structure Structures}.
  */
-public class IngredientPreset {
+public final class IngredientPreset {
 
     private final Map<Character, Ingredient> ingredientMap;
 
@@ -29,7 +29,7 @@ Map<Character, Ingredient> getIngredientMap() {
     /**
      * A builder for creating {@link IngredientPreset IngredientPresets}.
      */
-    public static class Builder extends AbstractIngredientMapper<Builder> {
+    public static final class Builder extends AbstractIngredientMapper<Builder> {
 
         private Builder() {}
 

invui/src/main/java/xyz/xenondevs/invui/gui/Markers.java

@@ -5,7 +5,7 @@
 /**
  * Contains markers
  */
-public class Markers {
+public final class Markers {
 
     /**
      * The marker for horizontal content list slots in {@link PagedGui PagedGuis},
@@ -41,4 +41,6 @@ void iterate(int width, int height, BiConsumer<? super Integer, ? super Integer>
 
     };
 
+    private Markers() {}
+    
 }

invui/src/main/java/xyz/xenondevs/invui/gui/Structure.java

@@ -12,7 +12,7 @@
 /**
  * Provides an easy way to design {@link Gui Guis} via a pattern string and ingredients.
  */
-public class Structure extends AbstractIngredientMapper<Structure> {
+public final class Structure extends AbstractIngredientMapper<Structure> {
 
     private static final HashMap<Character, Ingredient> globalIngredientMap = new HashMap<>();
     private static boolean globalIngredientsFrozen = false;

invui/src/main/java/xyz/xenondevs/invui/i18n/Languages.java

@@ -28,7 +28,7 @@
 /**
  * Handles localization of items and window titles.
  */
-public class Languages {
+public final class Languages {
 
     private static final Languages INSTANCE = new Languages();
     private final Map<Locale, Map<? extends String, ? extends String>> translations = new HashMap<>();
@@ -54,8 +54,7 @@ protected String getMiniMessageString(String key, Locale locale) {
 
     };
 
-    private Languages() {
-    }
+    private Languages() {}
 
     /**
      * Gets the singleton instance of Languages.

invui/src/main/java/xyz/xenondevs/invui/inventory/VirtualInventoryManager.java

@@ -16,7 +16,7 @@
 /**
  * Automatically reads and writes {@link VirtualInventory VirtualInventories} to files when the server starts and stops.
  */
-public class VirtualInventoryManager {
+public final class VirtualInventoryManager {
 
     private static final File SAVE_DIR = new File("plugins/InvUI/VirtualInventory/" + InvUI.getInstance().getPlugin().getName() + "/");
     private static final VirtualInventoryManager INSTANCE = new VirtualInventoryManager();

invui/src/main/java/xyz/xenondevs/invui/util/ColorPalette.java

@@ -9,7 +9,7 @@
 /**
  * Utility for converting images into the color space used by maps in Minecraft.
  */
-public class ColorPalette {
+public final class ColorPalette {
 
     private static final byte[] colorCache;
 
@@ -24,6 +24,8 @@ public class ColorPalette {
         colorCache = out.toByteArray();
     }
 
+    private ColorPalette() {}
+    
     /**
      * Gets the closest map color to the given RGB values.
      *

invui/src/main/java/xyz/xenondevs/invui/util/ItemUtils.java

@@ -13,11 +13,13 @@
  * Generic item-related utilities.
  */
 @SuppressWarnings("UnstableApiUsage")
-public class ItemUtils {
+public final class ItemUtils {
 
     private static @Nullable ItemStack placeholder;
     private static @Nullable ItemWrapper placeholderProvider;
 
+    private ItemUtils() {}
+    
     /**
      * Checks whether the given {@link ItemStack} is empty.
      * <p>