diff --git a/Test/praktikum01/ZahlenfilterTest.java b/Test/praktikum01/ZahlenfilterTest.java
index c73ed99..0bd989c 100644
--- a/Test/praktikum01/ZahlenfilterTest.java
+++ b/Test/praktikum01/ZahlenfilterTest.java
@@ -18,10 +18,13 @@ class ZahlenfilterTest {
 
     @Test
     void checkEndsWith9() {
+        assertTrue(Zahlenfilter.checkEndsWith9(9));
+        assertFalse(Zahlenfilter.checkEndsWith9(6));
 
     }
 
     @Test
     void checkSumDivisibleBy3() {
+
     }
 }
\ No newline at end of file
diff --git a/src/praktikum01/ErrorWriter.java b/src/praktikum01/ErrorWriter.java
index ee8f49c..722002b 100644
--- a/src/praktikum01/ErrorWriter.java
+++ b/src/praktikum01/ErrorWriter.java
@@ -1,6 +1,6 @@
 package praktikum01;
 
-public class ErrorWriter implements HelloWorldTest{
+public class ErrorWriter implements HelloWorld {
     @Override
     public void writeHelloWorld() {
         System.err.println("HELLO WORLD");
diff --git a/src/praktikum01/Executor.java b/src/praktikum01/Executor.java
index 51c8e7e..19363af 100644
--- a/src/praktikum01/Executor.java
+++ b/src/praktikum01/Executor.java
@@ -1,9 +1,18 @@
 package praktikum01;
 
-public class Executor implements HelloWorldTest{
+public class Executor{
 
-    @Override
-    public void printHelloWorld() {
+    public static void main(String[] args) {
+
+        printHelloWorld(new ErrorWriter(), new OutWriter(), false);
+    }
+
+
+    public static void printHelloWorld(HelloWorld writer1, HelloWorld writer2, boolean second) {
+        if (second)
+            writer2.writeHelloWorld();
+        else
+            writer1.writeHelloWorld();
 
     }
 }
diff --git a/src/praktikum01/HelloWorldTest.java b/src/praktikum01/HelloWorld.java
similarity index 61%
rename from src/praktikum01/HelloWorldTest.java
rename to src/praktikum01/HelloWorld.java
index cd093dc..e4e0864 100644
--- a/src/praktikum01/HelloWorldTest.java
+++ b/src/praktikum01/HelloWorld.java
@@ -1,6 +1,6 @@
 package praktikum01;
 
-public interface HelloWorldTest {
+public interface HelloWorld {
     void writeHelloWorld();
 
 }
diff --git a/src/praktikum01/OutWriter.java b/src/praktikum01/OutWriter.java
index 6041702..04c866e 100644
--- a/src/praktikum01/OutWriter.java
+++ b/src/praktikum01/OutWriter.java
@@ -1,6 +1,6 @@
 package praktikum01;
 
-public class OutWriter implements HelloWorldTest{
+public class OutWriter implements HelloWorld {
     @Override
     public void writeHelloWorld() {
         System.out.println("HELLO WORLD");