implement solution

Author: SteffenLm

Exercise.java

@@ -1,7 +1,9 @@
 public class Exercise {
 
   public static void main(String[] args) {
+    TravelAgency travelAgency = new TravelAgency("Reisebuero Schmidt");
     Rental rental = new Rental("Fahrzeugvermietung Mueller");
+    travelAgency.addPartner(rental);
 
     Car car1 = new Car("Porsche", "911", Engine.ELECTRO, 2);
     Truck truck1 = new Truck("MAN", "TGX", Engine.DIESEL, 20);
@@ -11,6 +13,6 @@ public static void main(String[] args) {
     rental.addVehicle(truck1);
     rental.addVehicle(car2);
 
-    rental.print();
+    travelAgency.print();
   }
 }

Partner.java

@@ -0,0 +1,3 @@
+public interface Partner {
+  void print();
+}

Rental.java

@@ -1,6 +1,6 @@
 import java.util.ArrayList;
 
-public class Rental {
+public class Rental implements Partner{
 
   private String name;
   private ArrayList<Vehicle> vehicles;

TravelAgency.java

@@ -0,0 +1,23 @@
+import java.util.ArrayList;
+
+public class TravelAgency {
+
+  private String name;
+  private ArrayList<Partner> partners;
+
+  public TravelAgency(String name) {
+    this.name = name;
+    partners = new ArrayList<>();
+  }
+
+  public void addPartner(Partner partner) {
+    partners.add(partner);
+  }
+
+  public void print() {
+    System.out.println(name);
+    for (Partner p : partners) {
+      p.print();
+    }
+  }
+}