Update

pp.A4-HandOverHandLocking/src/main/java/pp/Main.java

@@ -13,7 +13,8 @@ public class Main {
             if (sum != expected) {
                 System.out.println("Fehler in "
                         + Thread.currentThread().getName() + ": " + sum);
-            }
+            }else
+            	System.out.println("Kein Fehler in " + Thread.currentThread().getName() + ": " + sum);
         };
     }
 

pp.A4-HandOverHandLocking/src/main/java/pp/SimplifiedList.java

@@ -7,6 +7,7 @@ public interface SimplifiedList<T> {
      *
      * @param index index of the element to return
      * @return the element at the specified position in this list
+     * @throws Exception 
      */
     public T get(int index);
 
@@ -28,6 +29,7 @@ public interface SimplifiedList<T> {
      * @param index   index of the element to replace
      * @param element element to be stored at the specified position
      * @return the element previously at the specified position
+     * @throws Exception 
      */
     public T set(int index, T element);
 

pp.A4-HandOverHandLocking/src/main/java/pp/ThreadsafeSimplifiedList.java

@@ -29,8 +29,13 @@ public class ThreadsafeSimplifiedList<T>
      * @return the element at the specified position in this list
      */
     @Override
-    public T get(int index) {
+    public T get(int index){
         this.listLock.lock();
+        if (this.head == null) {
+        	this.listLock.unlock();
+        	throw new IndexOutOfBoundsException("The list is empty");    
+        }
+        
         var ptr = this.head;
         ptr.nodeLock.lock();
         this.listLock.unlock();
@@ -91,6 +96,10 @@ public class ThreadsafeSimplifiedList<T>
     @Override
     public T set(int index, T element) {
         this.listLock.lock();
+        if (this.head == null) {
+        	this.listLock.unlock();
+        	throw new IndexOutOfBoundsException("The list is empty");    
+        }
         var ptr = this.head;
         ptr.nodeLock.lock();
         this.listLock.unlock();