Added abstract 'PowerCard' class.

Added the abstract 'PowerCard' class to this project. It will be used to display different types of hand cards.

Projekte/mdga/model/src/main/java/pp/mdga/game/card/PowerCard.java

@@ -0,0 +1,86 @@
+package pp.mdga.game.card;
+
+import com.jme3.network.serializing.Serializable;
+import pp.mdga.game.BonusCard;
+import pp.mdga.visitor.Visitor;
+
+import java.util.UUID;
+
+/**
+ * This abstract class represents the abstract power class which will be used to realize a visitor pattern for all
+ * types of different cards inside the game.
+ */
+@Serializable
+public abstract class PowerCard {
+    /**
+     * Create PowerCard attributes.
+     */
+    private final UUID uuid = UUID.randomUUID();
+    private final BonusCard card;
+
+    /**
+     * Constructor.
+     */
+    public PowerCard() {
+        this.card = BonusCard.HIDDEN;
+    }
+
+    /**
+     * Constructor.
+     *
+     * @param card as the card type of this PowerCard class as BonusCard enumeration.
+     */
+    public PowerCard(BonusCard card) {
+        this.card = card;
+    }
+
+    /**
+     * This method will be used to call the visit method of the given visitor parameter and pass a PowerCard object.
+     *
+     * @param visitor as the visitor which will differentiates between all types of power card types as a Visitor
+     *                interface.
+     */
+    public abstract void accept(Visitor visitor);
+
+    /**
+     * This method will be used to return uuid attribute of abstract PowerCard class.
+     *
+     * @return uuid as a UUID object.
+     */
+    public UUID getUuid() {
+        return this.uuid;
+    }
+
+    /**
+     * This method will be used to create the hash code of this abstract PowerCard class.
+     *
+     * @return hashCode as an Integer.
+     */
+    @Override
+    public int hashCode() {
+        return this.uuid.hashCode();
+    }
+
+    /**
+     * This method will be used to check if the given obj parameter is equal to this object.
+     * It will return false if the obj parameter is null or if the hash codes of both objects are not equal. Otherwise
+     * it will return true.
+     *
+     * @param obj as the object which will be compared as an Object.
+     * @return true or false.
+     */
+    @Override
+    public boolean equals(Object obj) {
+        if (obj == null) {
+            return false;
+        }
+
+        if (obj instanceof PowerCard) {
+            PowerCard card = (PowerCard) obj;
+
+            return this.hashCode() == card.hashCode();
+        }
+
+        return false;
+    }
+}