refactoring: PropertyChangeSupport in Card

src/main/java/de/hsfulda/onses/models/Card.java

@@ -1,6 +1,14 @@
 package de.hsfulda.onses.models;
 
+import java.beans.PropertyChangeSupport;
+
 public class Card {
+
+    public final static String PROPERTY_COLOR = "color";
+    public final static String PROPERTY_VALUE = "value";
+
+    protected PropertyChangeSupport listeners;
+
     private Color color;
     private Value value;
 
@@ -12,12 +20,16 @@ public class Card {
     };
 
     public Card setColor(Color color) {
+        final Card.Color oldColor = this.color;
         this.color = color;
+        this.firePropertyChange(PROPERTY_COLOR, oldColor, color);
         return this;
     }
 
     public Card setValue(Value value) {
+        final Card.Value oldValue = this.value;
         this.value = value;
+        this.firePropertyChange(PROPERTY_VALUE, oldValue, value);
         return this;
     }
 
@@ -28,4 +40,19 @@ public class Card {
     public Value getValue() {
         return this.value;
     }
+
+    public PropertyChangeSupport listeners() {
+        if(this.listeners == null) {
+            this.listeners = new PropertyChangeSupport(this);
+        }
+        return this.listeners;
+    }
+
+    public boolean firePropertyChange(String propertyName, Object oldValue, Object newValue) {
+        if (this.listeners != null) {
+            this.listeners.firePropertyChange(propertyName, oldValue, newValue);
+            return true;
+        }
+        return false;
+    }
 }