diff --git a/src/main/java/de/joethei/hs/java2/praktikum/praktikum4/KlausurenServer.java b/src/main/java/de/joethei/hs/java2/praktikum/praktikum4/KlausurenServer.java
index 67cf11e..802872b 100644
--- a/src/main/java/de/joethei/hs/java2/praktikum/praktikum4/KlausurenServer.java
+++ b/src/main/java/de/joethei/hs/java2/praktikum/praktikum4/KlausurenServer.java
@@ -48,35 +48,17 @@ public class KlausurenServer {
                 ConcurrentMap<String, TreeSet<Integer>> set = new ConcurrentHashMap<>(data);
                 Set<TreeSet<Integer>> result = new HashSet<>();
 
-                set.forEach((key, value) -> {
-                    set.forEach((s, integers) -> {
-                        if(!value.equals(integers)) {
-                            if (integers.containsAll(value)) {
-                                set.remove(key);
-                            }
+                set.forEach((key, value) -> set.forEach((s, integers) -> {
+                    if(!value.equals(integers)) {
+                        if (integers.containsAll(value)) {
+                            set.remove(key);
                         }
-                    });
-                });
-
-                set.forEach((key, value) -> {
-                    result.add(value);
-                });
-
-                /*
-                data.forEach((key, value) -> {
-                    result.forEach(integers -> {
-                        if(!integers.containsAll(value)) {
-                            result.add(integers);
-                        }
-                    });
-                });
-                */
-                Iterator<TreeSet<Integer>> iterator = result.iterator();
-                while (iterator.hasNext()) {
-                    if(iterator.next().isEmpty()) {
-                     iterator.remove();
                     }
-                }
+                }));
+
+                set.forEach((key, value) -> result.add(value));
+
+                result.removeIf(TreeSet::isEmpty);
 
                 writer.write(result.toString().substring(1, result.toString().length()-1).replace(" ", ""));
             } else {
@@ -138,7 +120,7 @@ public class KlausurenServer {
         } catch (FileNotFoundException e) {
             e.printStackTrace();
         }
-        try (BufferedReader br = new BufferedReader(fileReader)) {
+        try (BufferedReader br = new BufferedReader(Objects.requireNonNull(fileReader))) {
             for (String line = br.readLine(); line != null; line = br.readLine()) {
                 TreeSet<Integer> set = new TreeSet<>();
                 String[] array = line.split(":");
diff --git a/src/main/resources/praktikum3/vorlesungen-db.txt b/src/main/resources/praktikum3/vorlesungen-db.txt
index 5fbff2c..59b11ad 100644
--- a/src/main/resources/praktikum3/vorlesungen-db.txt
+++ b/src/main/resources/praktikum3/vorlesungen-db.txt
@@ -1,4 +1,4 @@
-A1:Relativitätstheorie:Einstein:15
+A1:Relativitätstheorie:Einstein:15
 B2:Quantenmechanik:Heisenberg:17
 C2:Quantenphysik:Planck:5
 T4:Thermodynamik:Kelvin:78