first version of pattern without Tests

extension-objects/src/main/java/App.java

@@ -0,0 +1,59 @@
+import abstractextensions.CommanderExtension;
+import abstractextensions.SergeantExtension;
+import abstractextensions.SoldierExtension;
+import units.CommanderUnit;
+import units.SergeantUnit;
+import units.SoldierUnit;
+import units.Unit;
+
+/**
+ * Created by Srdjan on 26-Apr-17.
+ */
+public class App {
+
+  /**
+   * Program entry point
+   *
+   * @param args command line args
+   */
+  public static void main(String[] args) {
+
+    //Create 3 different units
+    Unit unit = new SoldierUnit("SoldierUnit1");
+    Unit unit1 = new SergeantUnit("SergeantUnit1");
+    Unit unit2 = new CommanderUnit("CommanderUnit1");
+
+    //check for each unit to have an extension
+    checkExtensionsForUnit(unit);
+    checkExtensionsForUnit(unit1);
+    checkExtensionsForUnit(unit2);
+
+  }
+
+  private static void checkExtensionsForUnit(Unit unit) {
+    //separate for better view
+    System.out.println();
+
+    SoldierExtension soldierExtension = (SoldierExtension) unit.getUnitExtension("SoldierExtension");
+    SergeantExtension sergeantExtension = (SergeantExtension) unit.getUnitExtension("SergeantExtension");
+    CommanderExtension commanderExtension = (CommanderExtension) unit.getUnitExtension("CommanderExtension");
+
+    if (soldierExtension != null) {
+      soldierExtension.soldierReady();
+    } else {
+      System.out.println(unit.getName() + " without SoldierExtension");
+    }
+
+    if (sergeantExtension != null) {
+      sergeantExtension.sergeantReady();
+    } else {
+      System.out.println(unit.getName() + " without SergeantExtension");
+    }
+
+    if (commanderExtension != null) {
+      // commanderExtension.sergeantReady();
+    } else {
+      System.out.println(unit.getName() + " without CommanderExtension");
+    }
+  }
+}