final

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

@@ -13,8 +13,7 @@ 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

@@ -7,7 +7,6 @@ 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);
 
@@ -29,7 +28,6 @@ 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

@@ -29,14 +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;
+    if (ptr == null) {
+      this.listLock.unlock();
+      throw new IndexOutOfBoundsException(index + " out of bounds (empty list)");
+    }
     ptr.nodeLock.lock();
     this.listLock.unlock();
     for (var i = 0; i < index; i++) {
@@ -46,12 +45,16 @@ public class ThreadsafeSimplifiedList<T>
         ptr = ptr.next;
         savePtr.nodeLock.unlock();
       } else {
+        ptr.nodeLock.unlock();
         throw new IndexOutOfBoundsException(index + " out of bounds");
       }
     }
 
-        try {return delay(ptr.element);} 
+    try {
-        finally { ptr.nodeLock.unlock();}
+      return delay(ptr.element);
+    } finally {
+      ptr.nodeLock.unlock();
+    }
   }
 
   /**
@@ -96,11 +99,11 @@ 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;
+    if (ptr == null) {
+      this.listLock.unlock();
+      throw new IndexOutOfBoundsException(index + " out of bounds (empty list)");
+    }
     ptr.nodeLock.lock();
     this.listLock.unlock();
     for (var i = 0; i < index; i++) {
@@ -109,13 +112,16 @@ public class ThreadsafeSimplifiedList<T>
         var savePtr = ptr;
         ptr = ptr.next;
         savePtr.nodeLock.unlock();
-            } else 
+      } else {
+        ptr.nodeLock.unlock();
         throw new IndexOutOfBoundsException(index + " out of bounds");
-           
       }
+    }
+
     try {
+      T old = ptr.element;
       ptr.element = element;
-            return element;
+      return old;
     } finally {
       ptr.nodeLock.unlock();
     }
@@ -129,7 +135,10 @@ public class ThreadsafeSimplifiedList<T>
   @Override
   public boolean isEmpty() {
     this.listLock.lock();
-        try { return this.head == null; } 
+    try {
-        finally { this.listLock.unlock();}
+      return this.head == null;
+    } finally {
+      this.listLock.unlock();
+    }
   }
 }