Added various new panel types (#917)

* Add multiple different types of panel.
- Inventory panel -> current
- Hooper panel -> 5 slot panel
- Dropper panel -> 9 slot in 3 rows

* code formatting and javadoc improvements in Panel

* renamed PanelType to Type

* updated to new enum name + javadoc

src/main/java/world/bentobox/bentobox/api/panels/Panel.java

@@ -7,6 +7,7 @@ import java.util.stream.Collectors;
 import org.bukkit.Bukkit;
 import org.bukkit.Material;
 import org.bukkit.entity.Player;
+import org.bukkit.event.inventory.InventoryType;
 import org.bukkit.inventory.Inventory;
 import org.bukkit.inventory.InventoryHolder;
 import org.bukkit.inventory.ItemStack;
@@ -31,19 +32,55 @@ public class Panel implements HeadRequester, InventoryHolder {
     private User user;
     private String name;
 
-    public Panel(String name, Map<Integer, PanelItem> items, int size, User user, PanelListener listener) {
-        makePanel(name, items, size, user, listener);
+    /**
+     * Various types of Panel that can be created.
+     * @since 1.7.0
+     */
+    public enum Type {
+        INVENTORY,
+        HOPPER,
+        DROPPER
     }
 
     public Panel() {}
 
+    public Panel(String name, Map<Integer, PanelItem> items, int size, User user, PanelListener listener) {
+        this(name, items, size, user, listener, Type.INVENTORY);
+    }
+
+    /**
+     * @since 1.7.0
+     */
+    public Panel(String name, Map<Integer, PanelItem> items, int size, User user, PanelListener listener, Type type) {
+        makePanel(name, items, size, user, listener, type);
+    }
+
     protected void makePanel(String name, Map<Integer, PanelItem> items, int size, User user,
-            PanelListener listener) {
+        PanelListener listener) {
+        this.makePanel(name, items, size, user, listener, Type.INVENTORY);
+    }
+
+    /**
+     * @since 1.7.0
+     */
+    protected void makePanel(String name, Map<Integer, PanelItem> items, int size, User user,
+            PanelListener listener, Type type) {
         this.name = name;
         this.items = items;
-        size = fixSize(size);
+
         // Create panel
-        inventory = Bukkit.createInventory(null, size, name);
+        switch (type) {
+            case INVENTORY:
+                inventory = Bukkit.createInventory(null, fixSize(size), name);
+                break;
+            case HOPPER:
+                inventory = Bukkit.createInventory(null, InventoryType.HOPPER, name);
+                break;
+            case DROPPER:
+                inventory = Bukkit.createInventory(null, InventoryType.DROPPER, name);
+                break;
+        }
+
         // Fill the inventory and return
         for (Map.Entry<Integer, PanelItem> en: items.entrySet()) {
             if (en.getKey() < 54) {

src/main/java/world/bentobox/bentobox/api/panels/builders/PanelBuilder.java

@@ -21,6 +21,7 @@ public class PanelBuilder {
     private int size;
     private User user;
     private PanelListener listener;
+    private Panel.Type type = Panel.Type.INVENTORY;
 
     public PanelBuilder name(String name) {
         this.name = ChatColor.translateAlternateColorCodes('&', name);
@@ -85,6 +86,18 @@ public class PanelBuilder {
         return this;
     }
 
+    /**
+     * Sets which Panel.Type will be used.
+     * Defaults to {@link Panel.Type#INVENTORY}.
+     * @param type - Panel.Type for this panel.
+     * @return PanelBuilder
+     * @since 1.7.0
+     */
+    public PanelBuilder type(Panel.Type type) {
+        this.type = type;
+        return this;
+    }
+
     /**
      * Get the next free slot number after the largest slot.
      * @return next slot number, or -1 in case none has been found.
@@ -108,7 +121,7 @@ public class PanelBuilder {
      */
     public Panel build() {
         // items.lastKey() is a slot position, so the panel size is this value + 1
-        return new Panel(name, items, Math.max(size, items.isEmpty() ? size : items.lastKey() + 1), user, listener);
+        return new Panel(name, items, Math.max(size, items.isEmpty() ? size : items.lastKey() + 1), user, listener, type);
     }
 
     /**
@@ -145,4 +158,13 @@ public class PanelBuilder {
     public PanelListener getListener() {
         return listener;
     }
+
+
+    /**
+     * @return the panelType
+     * @since 1.7.0
+     */
+    public Panel.Type getPanelType() {
+        return type;
+    }
 }