added mediator sample

mediator/src/main/java/com/iluwatar/PartyMemberBase.java

@@ -0,0 +1,46 @@
+package com.iluwatar;
+
+public abstract class PartyMemberBase implements PartyMember {
+
+	protected Party party;
+
+	@Override
+	public void joinedParty(Party party) {
+		System.out.println(this + " joins the party");
+		this.party = party;
+	}
+
+	@Override
+	public void partyAction(Action action) {
+		String s = this + " ";
+		switch (action) {
+		case ENEMY:
+			s = s + "runs for cover";
+			break;
+		case GOLD:
+			s = s + "takes his share of the gold";
+			break;
+		case HUNT:
+			s = s + "arrives for dinner";
+			break;
+		case TALE:
+			s = s + "comes to listen";
+			break;
+		default:
+			break;
+		}
+		System.out.println(s);
+	}
+	
+	@Override
+	public void act(Action action) {
+		if (party != null) {
+			System.out.println(this + " " + action.toString());
+			party.act(this, action);
+		}
+	}
+
+	@Override
+	public abstract String toString();
+	
+}