diff --git a/src/Main.java b/src/Main.java
index 3e59c38..3430513 100644
--- a/src/Main.java
+++ b/src/Main.java
@@ -1,5 +1,21 @@
+import de.hsmannheim.informatik.name.domain.RobotFactory;
+import de.hsmannheim.informatik.name.domain.RobotType;
+import de.hsmannheim.informatik.name.domain.exceptions.RobotIllegalStateException;
+import java.util.Random;
+
 public class Main {
-    public static void main(String[] args) {
-        System.out.println("Hello world!");
+    public static void main(String[] args) throws RobotIllegalStateException {
+        Random r = new Random();
+        RobotFactory rf = new RobotFactory();
+        RobotType R2D2 = RobotType.R2D2;
+        RobotType C3P0 = RobotType.C3P0;
+        for (int i = 0; i < 10000; i++) {
+            rf.getRobot(R2D2, 0);
+        }
+        System.out.println("finished R2D2");
+        for (int i = 0; i < 10000; i++) {
+            rf.getRobot(C3P0, 0);
+        }
+        System.out.println("finished C3P0");
     }
 }
\ No newline at end of file
diff --git a/src/de/hsmannheim/informatik/name/domain/RobotFactory.java b/src/de/hsmannheim/informatik/name/domain/RobotFactory.java
index aae92fa..e14e2f8 100644
--- a/src/de/hsmannheim/informatik/name/domain/RobotFactory.java
+++ b/src/de/hsmannheim/informatik/name/domain/RobotFactory.java
@@ -5,6 +5,10 @@ import de.hsmannheim.informatik.name.domain.requirements.Robot;
 import de.hsmannheim.informatik.name.domain.starwars.C3PO;
 import de.hsmannheim.informatik.name.domain.starwars.R2D2;
 
+import java.util.HashSet;
+import java.util.Random;
+import java.util.Set;
+
 /**
  * <h1>RobotFactory</h1>
  * <p>
@@ -13,6 +17,8 @@ import de.hsmannheim.informatik.name.domain.starwars.R2D2;
  * @see RobotType
  */
 public class RobotFactory {
+    private Set<Integer> serialNumbersR2D2 = new HashSet<>();
+    private Set<Integer> serialNumbersC3P0 = new HashSet<>();
 
     /**
      * Factory Method to get a {@link Robot}
@@ -23,12 +29,38 @@ public class RobotFactory {
      * @throws RobotIllegalStateException the robot initializes in an illegal state
      */
     public Robot getRobot(RobotType type, int serialNumber) throws RobotIllegalStateException {
+        Random r = new Random();
+        boolean usedSerialNumber = true;
         switch (type) {
             case C3P0 -> {
-                return new C3PO(serialNumber);
+                int serialNumberC3P0;
+                do{
+//                    String temp = String.format("%04d", r.nextInt(1000)+10000);
+                    serialNumberC3P0 = r.nextInt(10000)+10000;
+                    if(!serialNumbersC3P0.contains(serialNumberC3P0)){
+                        serialNumbersC3P0.add(serialNumberC3P0);
+                        usedSerialNumber = false;
+                    }
+                }while(usedSerialNumber);
+                //Debug output
+                    System.out.println(serialNumberC3P0);
+                //
+                return new C3PO(serialNumberC3P0);
             }
             case R2D2 -> {
-                return new R2D2(serialNumber);
+                int serialNumberR2D2;
+                do{
+                    String temp = String.format("%05d", r.nextInt(10000));
+                    serialNumberR2D2 = Integer.parseInt(temp);
+                    if(!serialNumbersR2D2.contains(serialNumberR2D2)){
+                        serialNumbersR2D2.add(serialNumberR2D2);
+                        usedSerialNumber = false;
+                    }
+                }while(usedSerialNumber);
+                //Debug output
+                System.out.println(serialNumberR2D2);
+                //
+                return new R2D2(serialNumberR2D2);
             }
             default -> {
                 return null;
diff --git a/src/de/hsmannheim/informatik/name/domain/starwars/C3PO.java b/src/de/hsmannheim/informatik/name/domain/starwars/C3PO.java
index 3843f6b..cd99b3a 100644
--- a/src/de/hsmannheim/informatik/name/domain/starwars/C3PO.java
+++ b/src/de/hsmannheim/informatik/name/domain/starwars/C3PO.java
@@ -24,6 +24,7 @@ public class C3PO extends StarWarsRobot {
 
     /**
      * C3PO think method sorts numbers with insertion sort in descending order
+     *
      * @param numbers integer numbers for sorting
      * @return arrToSort integer array with numbers sorted in descending order
      * @throws RobotException
diff --git a/src/de/hsmannheim/informatik/name/domain/starwars/R2D2.java b/src/de/hsmannheim/informatik/name/domain/starwars/R2D2.java
index 7650119..855bbd8 100644
--- a/src/de/hsmannheim/informatik/name/domain/starwars/R2D2.java
+++ b/src/de/hsmannheim/informatik/name/domain/starwars/R2D2.java
@@ -24,6 +24,7 @@ public class R2D2 extends StarWarsRobot {
 
     /**
      * R2D2 think method sorts numbers with selection sort in ascending order
+     *
      * @param numbers integer numbers for sorting
      * @return arrayToSort integer array with numbers sorted in ascending order
      * @throws RobotException