diff --git a/.devcontainer.json b/.devcontainer.json
new file mode 100644
index 0000000..bfbeb0d
--- /dev/null
+++ b/.devcontainer.json
@@ -0,0 +1,3 @@
+{
+    "image": "mcr.microsoft.com/devcontainers/java:21"
+}
\ No newline at end of file
diff --git a/.vscode/extensions.json b/.vscode/extensions.json
new file mode 100644
index 0000000..add4f4e
--- /dev/null
+++ b/.vscode/extensions.json
@@ -0,0 +1,5 @@
+{
+    "recommendations": [
+        "vscjava.vscode-java-pack"
+    ]
+}
\ No newline at end of file
diff --git a/Exercise.java b/Exercise.java
index 2d4d392..e2cdec7 100644
--- a/Exercise.java
+++ b/Exercise.java
@@ -21,6 +21,8 @@ public static void main(String[] args) {
     rental.addVehicle(truck1);
     rental.addVehicle(car2);
 
+    rental.transformAllTrucks();
+
     System.out.println(rental.toString());
   }
 }
diff --git a/Rental.java b/Rental.java
index 218eb37..37194a5 100644
--- a/Rental.java
+++ b/Rental.java
@@ -28,6 +28,15 @@ public void addAllVehicles(Vehicle... vehicles) {
     }
   }
 
+  public void transformAllTrucks() {
+    for (Vehicle c : vehicles) {
+      if (c instanceof Truck) {
+        Truck t = (Truck) c;
+        if (!t.isTransformed()) t.transform();
+      }
+    }
+  }
+
   public String toString() {
     String result = name + "\n" + "Unsere Fahrzeuge: \n";
     for (Vehicle vehicle : vehicles) {