All without Readme and pumlid

marker/src/main/java/App.java

@@ -1,12 +1,43 @@
 /**
  * Created by Alexis on 28-Apr-17.
+ * With Marker interface idea is to make empty interface and extend it.
+ * Basically it is just to identify the special objects from normal objects.
+ * Like in case of serialization , objects that need to be serialized must implement serializable interface
+ * (it is empty interface) and down the line writeObject() method must be checking
+ * if it is a instance of serializable or not.
+ * <p>
+ * Marker interface vs annotation
+ * Marker interfaces and marker annotations both have their uses,
+ * neither of them is obsolete or always better then the other one.
+ * If you want to define a type that does not have any new methods associated with it,
+ * a marker interface is the way to go.
+ * If you want to mark program elements other than classes and interfaces,
+ * to allow for the possibility of adding more information to the marker in the future,
+ * or to fit the marker into a framework that already makes heavy use of annotation types,
+ * then a marker annotation is the correct choice
  */
 public class App {
+
+  /**
+   * Program entry point
+   *
+   * @param args command line args
+   */
   public static void main(String[] args) {
+
     Guard guard = new Guard();
+    Thief thief = new Thief();
 
     if (guard instanceof Permission) {
       guard.enter();
+    } else {
+      System.out.println("You have no permission to enter, please leave this area");
+    }
+
+    if (thief instanceof Permission) {
+      thief.steal();
+    } else {
+      thief.doNothing();
     }
   }
 }

marker/src/main/java/Thief.java

@@ -0,0 +1,12 @@
+/**
+ * Created by Alexis on 02-May-17.
+ */
+public class Thief {
+  protected static void steal() {
+    System.out.println("Steal valuable items");
+  }
+
+  protected static void doNothing() {
+    System.out.println("Pretend nothing happened and just leave");
+  }
+}