Update inventory implementation style

src/client/java/minicraft/entity/furniture/Chest.java

@@ -8,6 +8,7 @@
 import minicraft.gfx.SpriteLinker.LinkedSprite;
 import minicraft.gfx.SpriteLinker.SpriteType;
 import minicraft.item.BoundedInventory;
+import minicraft.item.FixedInventory;
 import minicraft.item.Inventory;
 import minicraft.item.Item;
 import minicraft.item.Items;
@@ -36,7 +37,7 @@ public Chest(String name) {
 	 * @param name Name of chest.
 	 */
 	public Chest(String name, LinkedSprite itemSprite) {
-		this(new BoundedInventory(), name, itemSprite); // Default with bounded inventory
+		this(new FixedInventory(), name, itemSprite); // Default with bounded inventory
 	}
 
 	protected Chest(Inventory inventory, String name, LinkedSprite itemSprite) {
@@ -89,7 +90,7 @@ public Inventory getInventory() {
 	@Override
 	public void die() {
 		if (level != null) {
-			List<Item> items = inventory.getItems();
+			List<Item> items = inventory.getItemsView();
 			level.dropItem(x, y, items.toArray(new Item[0]));
 		}
 		super.die();

src/client/java/minicraft/entity/furniture/DeathChest.java

@@ -11,10 +11,8 @@
 import minicraft.gfx.Screen;
 import minicraft.gfx.SpriteLinker.LinkedSprite;
 import minicraft.gfx.SpriteLinker.SpriteType;
-import minicraft.item.BoundedInventory;
 import minicraft.item.Inventory;
 import minicraft.item.Item;
-import minicraft.item.StackableItem;
 import minicraft.item.UnlimitedInventory;
 
 public class DeathChest extends Chest {
@@ -46,7 +44,7 @@ public DeathChest(Player player) {
 		this();
 		this.x = player.x;
 		this.y = player.y;
-		for (Item i : player.getInventory().getItems()) {
+		for (Item i : player.getInventory().getItemsView()) {
 			inventory.add(i.copy());
 		}
 	}
@@ -98,7 +96,7 @@ public boolean use(Player player) {
 	public void touchedBy(Entity other) {
 		if (other instanceof Player) {
 			Inventory playerInv = ((Player) other).getInventory();
-			for (Item i : inventory.getItems()) {
+			for (Item i : inventory.getItemsView()) {
 				if (playerInv.add(i) != null) {
 					Game.notifications.add("Your inventory is full!");
 					return;

src/client/java/minicraft/entity/mob/Player.java

@@ -29,6 +29,7 @@
 import minicraft.item.BoundedInventory;
 import minicraft.item.FishingData;
 import minicraft.item.FishingRodItem;
+import minicraft.item.FixedInventory;
 import minicraft.item.FurnitureItem;
 import minicraft.item.Inventory;
 import minicraft.item.Item;
@@ -147,7 +148,7 @@ public Player(@Nullable Player previousInstance, InputHandler input) {
 		y = 24;
 		this.input = input;
 		// Since this implementation will be deleted by Better Creative Mode Inventory might not implemented correctly
-		inventory = new BoundedInventory() { // Registering all triggers to InventoryChanged.
+		inventory = new FixedInventory() { // Registering all triggers to InventoryChanged.
 			private void triggerTrigger() {
 				AdvancementElement.AdvancementTrigger.InventoryChangedTrigger.INSTANCE.trigger(
 					new AdvancementElement.AdvancementTrigger.InventoryChangedTrigger.InventoryChangedTriggerConditionHandler.InventoryChangedTriggerConditions(this)

src/client/java/minicraft/item/BoundedInventory.java

@@ -3,19 +3,14 @@
 import minicraft.util.Logging;
 import org.jetbrains.annotations.Nullable;
 
-public class BoundedInventory extends Inventory {
-	public static final int DEFAULT_SIZE = 27;
-
-	protected final int maxItem;
-
-	public BoundedInventory() { this(DEFAULT_SIZE); }
-	public BoundedInventory(int maxItem) {
-		this.maxItem = maxItem;
-	}
-
-	public int getMaxSlots() {
-		return maxItem;
-	}
+public abstract class BoundedInventory extends Inventory {
+	/**
+	 * Gets the current maximum capacity of inventory.
+	 * This value is capable to inventory expanding (e.g. upgrades), but not changing by other
+	 * conditions such as the contents.
+	 * @return current value of maximum capacity of general slots
+	 */
+	public abstract int getMaxSlots();
 
 	@Override
 	public @Nullable Item add(@Nullable Item item) {
@@ -26,6 +21,7 @@ public int getMaxSlots() {
 			return null;
 		}
 
+		int maxItem = getMaxSlots();
 		if (item instanceof StackableItem) { // If the item is a item...
 			StackableItem toTake = (StackableItem) item; // ...convert it into a StackableItem object.
 			for (Item value : items) {

src/client/java/minicraft/item/FixedInventory.java

@@ -0,0 +1,25 @@
+/*
+ * SPDX-FileCopyrightText: 2024 Minicraft+ contributors
+ * SPDX-License-Identifier: GPL-3.0-only
+ */
+
+package minicraft.item;
+
+/**
+ * A general inventory implementation with fixed size (number of slots).
+ */
+public class FixedInventory extends BoundedInventory {
+	public static final int DEFAULT_SIZE = 27;
+
+	protected final int maxSlots;
+
+	public FixedInventory() { this(DEFAULT_SIZE); }
+	public FixedInventory(int maxSlots) {
+		this.maxSlots = maxSlots;
+	}
+
+	@Override
+	public int getMaxSlots() {
+		return maxSlots;
+	}
+}

src/client/java/minicraft/item/Inventory.java

@@ -5,18 +5,28 @@
 import org.jetbrains.annotations.Nullable;
 
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 import java.util.Random;
 
+/**
+ * An item storage space for general purposes, based on the maximum number of item stacks,
+ * and the default item maximum count for stackable items.
+ * <p>
+ *     For special conditional storage space for items, like custom maximum count of items and
+ *     storage space that is variable to other conditions, slots or a custom implementation
+ *     is recommended instead.
+ * </p>
+ */
 public abstract class Inventory {
 	protected final List<Item> items = new ArrayList<>(); // The list of items that is in the inventory.
 
 	/**
 	 * Returns all the items which are in this inventory.
-	 * @return ArrayList containing all the items in the inventory.
+	 * @return a read-only view of the internal list containing all the items in the inventory.
 	 */
-	public List<Item> getItems() {
-		return new ArrayList<>(items);
+	public List<Item> getItemsView() {
+		return Collections.unmodifiableList(items);
 	}
 
 	public void clearInv() {

src/client/java/minicraft/item/UnlimitedInventory.java

@@ -3,6 +3,9 @@
 import minicraft.util.Logging;
 import org.jetbrains.annotations.Nullable;
 
+/**
+ * A general inventory implementation basically without size limit (maximum number of slots).
+ */
 public class UnlimitedInventory extends Inventory {
 	@Override
 	public @Nullable Item add(@Nullable Item item) {

src/client/java/minicraft/screen/InventoryMenu.java

@@ -21,7 +21,7 @@ class InventoryMenu extends ItemListMenu {
 	InventoryMenu(Entity holder, Inventory inv, String title, RelPos entryPos, @Nullable Action onStackUpdateListener) { this(holder, inv, title, entryPos, false, onStackUpdateListener); }
 	InventoryMenu(Entity holder, Inventory inv, String title, RelPos entryPos, boolean creativeInv) { this(holder, inv, title, entryPos, creativeInv, null); }
 	InventoryMenu(Entity holder, Inventory inv, String title, RelPos entryPos, boolean creativeInv, @Nullable Action onStackUpdateListener) {
-		super(ItemListMenu.getBuilder(entryPos), ItemEntry.useItems(inv.getItems()), title);
+		super(ItemListMenu.getBuilder(entryPos), ItemEntry.useItems(inv.getItemsView()), title);
 		this.inv = inv;
 		this.holder = holder;
 		this.title = title;
@@ -31,7 +31,7 @@ class InventoryMenu extends ItemListMenu {
 	}
 
 	InventoryMenu(InventoryMenu model) {
-		super(ItemListMenu.getBuilder(model.entryPos), ItemEntry.useItems(model.inv.getItems()), model.title);
+		super(ItemListMenu.getBuilder(model.entryPos), ItemEntry.useItems(model.inv.getItemsView()), model.title);
 		this.inv = model.inv;
 		this.holder = model.holder;
 		this.creativeInv = model.creativeInv;

src/client/java/minicraft/util/AdvancementElement.java

@@ -1,7 +1,6 @@
 package minicraft.util;
 
 import minicraft.core.World;
-import minicraft.entity.furniture.Chest;
 import minicraft.entity.furniture.RewardChest;
 import minicraft.item.BoundedInventory;
 import minicraft.item.Item;
@@ -925,7 +924,7 @@ public static class InventoryChangedTriggerConditions extends AdvancementTrigger
 					private final int maxSlots;
 
 					public InventoryChangedTriggerConditions(BoundedInventory inventory) {
-						items.addAll(inventory.getItems());
+						items.addAll(inventory.getItemsView());
 						maxSlots = inventory.getMaxSlots();
 					}
 				}