diff --git a/sources/.checkstyle b/sources/.checkstyle
index 069d5e6..3a5dd87 100644
--- a/sources/.checkstyle
+++ b/sources/.checkstyle
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 
-<fileset-config file-format-version="1.2.0" simple-config="false" sync-formatter="true">
+<fileset-config file-format-version="1.2.0" simple-config="false" sync-formatter="false">
   <local-check-config name="maven-checkstyle-plugin validate" location="file:/C:/Users/KTS%20Nitro%205/git/uebungen/sources/checkstyle.xml" type="remote" description="maven-checkstyle-plugin configuration validate">
     <property name="checkstyle.header.file" value="C:\Users\KTS Nitro 5\eclipse-workspace\PR2\.metadata\.plugins\org.eclipse.core.resources\.projects\sources\com.basistech.m2e.code.quality.checkstyleConfigurator\checkstyle-header-validate.txt"/>
     <property name="checkstyle.cache.file" value="${project_loc}/target/checkstyle-cachefile"/>
diff --git a/sources/.project b/sources/.project
index 09e671d..801ddf8 100644
--- a/sources/.project
+++ b/sources/.project
@@ -10,11 +10,6 @@
 			<arguments>
 			</arguments>
 		</buildCommand>
-		<buildCommand>
-			<name>net.sf.eclipsecs.core.CheckstyleBuilder</name>
-			<arguments>
-			</arguments>
-		</buildCommand>
 		<buildCommand>
 			<name>org.eclipse.m2e.core.maven2Builder</name>
 			<arguments>
@@ -24,6 +19,5 @@
 	<natures>
 		<nature>org.eclipse.m2e.core.maven2Nature</nature>
 		<nature>org.eclipse.jdt.core.javanature</nature>
-		<nature>net.sf.eclipsecs.core.CheckstyleNature</nature>
 	</natures>
 </projectDescription>
diff --git a/sources/src/main/java/pr2/vererbung/singleton_einfach/Singleton.java b/sources/src/main/java/pr2/vererbung/singleton_einfach/Singleton.java
index eaf2be4..8fd4f0b 100644
--- a/sources/src/main/java/pr2/vererbung/singleton_einfach/Singleton.java
+++ b/sources/src/main/java/pr2/vererbung/singleton_einfach/Singleton.java
@@ -1,26 +1,28 @@
 package pr2.vererbung.singleton_einfach;
 
- public class Singleton {
+ public final class Singleton {
      
-     private static String name;
-     Singleton sl = new Singleton("Alleine");
+     private String name;
      
-     public Singleton(String name) {
-         if (sl == null) {
-         this.setName(name);
-         } else {
-             getInfo();
-         }
-     }
-     public String getName() {
-        return name;
-     }
-     public void setName(String name) {
-        Singleton.name = name;
-     }
-        
-     public String getInfo() {
-         return "Der Singleton exsistiert bereits";
-     }
+     public static final Singleton SL = new Singleton();
+     
+     private Singleton() {
          
+     }
+     
+     private Singleton(String name) {
+         this.name = name;
+     }
+     
+     public static String getName() {
+        return SL.name;
+     }
+     
+     public static Singleton getInstance(String name) {
+         if (SL == null) {
+             return new Singleton(name);
+         } else {
+             return SL;
+         }  
+     }      
 }
diff --git a/sources/src/main/java/pr2/vererbung/singleton_einfach/SingletonTest.java b/sources/src/main/java/pr2/vererbung/singleton_einfach/SingletonTest.java
index 2426806..531452e 100644
--- a/sources/src/main/java/pr2/vererbung/singleton_einfach/SingletonTest.java
+++ b/sources/src/main/java/pr2/vererbung/singleton_einfach/SingletonTest.java
@@ -1,15 +1,31 @@
 package pr2.vererbung.singleton_einfach;
 
+import static org.junit.Assert.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 
+
 import org.junit.Test;
 
 public class SingletonTest {
 
     
+    @SuppressWarnings("static-access")
     @Test
     public void testVomSingleton() {
-        Singleton sl = new Singleton("Walter");
-        assertEquals("Walter", sl.getName());
+        
+        assertEquals("Alleine", Singleton.getName());
+        
+        assertEquals("Alleine", Singleton.getInstance("Alleine").getName());
+        
+        assertFalse(false);
+    }
+    
+    public void testNeueInstanz() {
+        
+        Singleton NN = Singleton.getInstance("Hubert");
+        
+        assertEquals("Hubert", Singleton.getName());
+        
+        
     }
 }
diff --git a/sources/src/main/java/pr2/vererbung/ueberschreiben_lebewesen/Amoebe.java b/sources/src/main/java/pr2/vererbung/ueberschreiben_lebewesen/Amoebe.java
index 02ea122..0042b99 100644
--- a/sources/src/main/java/pr2/vererbung/ueberschreiben_lebewesen/Amoebe.java
+++ b/sources/src/main/java/pr2/vererbung/ueberschreiben_lebewesen/Amoebe.java
@@ -1,5 +1,13 @@
 package pr2.vererbung.ueberschreiben_lebewesen;
 
- public class Amoebe {
+ public class Amoebe extends Lebewesen {
 
+     public Amoebe() {
+         
+     }
+     
+     @Override
+     public void bewegen() {
+         System.out.println("Schleimen");
+     }
 }
diff --git a/sources/src/main/java/pr2/vererbung/ueberschreiben_lebewesen/Dackel.java b/sources/src/main/java/pr2/vererbung/ueberschreiben_lebewesen/Dackel.java
index 1c5fd8a..fdce359 100644
--- a/sources/src/main/java/pr2/vererbung/ueberschreiben_lebewesen/Dackel.java
+++ b/sources/src/main/java/pr2/vererbung/ueberschreiben_lebewesen/Dackel.java
@@ -1,5 +1,17 @@
 package pr2.vererbung.ueberschreiben_lebewesen;
 
- public class Dackel {
+ public class Dackel extends Lebewesen {
 
+     public Dackel() {
+         
+     }
+     
+     @Override
+     public void bewegen() {
+         System.out.println("Auf kurzen Beinen vorwärts wackeln");
+     }
+     
+     public void bellen() {
+         System.out.println("Wau, wau");
+     }
 }
diff --git a/sources/src/main/java/pr2/vererbung/ueberschreiben_lebewesen/Lebewesen.java b/sources/src/main/java/pr2/vererbung/ueberschreiben_lebewesen/Lebewesen.java
index acde914..9888077 100644
--- a/sources/src/main/java/pr2/vererbung/ueberschreiben_lebewesen/Lebewesen.java
+++ b/sources/src/main/java/pr2/vererbung/ueberschreiben_lebewesen/Lebewesen.java
@@ -2,4 +2,11 @@ package pr2.vererbung.ueberschreiben_lebewesen;
 
 public class Lebewesen {
 
+    public Lebewesen() {
+        
+    }
+    
+    public void bewegen() {
+        
+    }
 }
diff --git a/sources/src/main/java/pr2/vererbung/ueberschreiben_lebewesen/Main.java b/sources/src/main/java/pr2/vererbung/ueberschreiben_lebewesen/Main.java
index ee3f3ba..e269a1d 100644
--- a/sources/src/main/java/pr2/vererbung/ueberschreiben_lebewesen/Main.java
+++ b/sources/src/main/java/pr2/vererbung/ueberschreiben_lebewesen/Main.java
@@ -3,6 +3,26 @@ package pr2.vererbung.ueberschreiben_lebewesen;
 public class Main {
 
     public static void main(String[] args) {
-        // TODO: Lebewesen testen
+
+
+        Lebewesen l1 = new Dackel();
+        Lebewesen l2 = new Amoebe();
+        
+        l1.bewegen();
+        l2.bewegen();
+        
+        if ((l1) instanceof Dackel) {
+            ((Dackel) l1).bellen();
+        } else {
+            System.out.println("l1 ist noch keine Instanz von Dackel");
+        }
+        
+        if (((Dackel) l1) instanceof Dackel) {
+            ((Dackel) l1).bellen();
+        } else {
+            System.out.println("l1 ist keine Instanz von Dackel");
+        }
+        
+        
     }
 }
diff --git a/sources/src/main/java/pr2/vererbung/vararg_summe/Summator.java b/sources/src/main/java/pr2/vererbung/vararg_summe/Summator.java
index f38b0ac..a10f74c 100644
--- a/sources/src/main/java/pr2/vererbung/vararg_summe/Summator.java
+++ b/sources/src/main/java/pr2/vererbung/vararg_summe/Summator.java
@@ -2,4 +2,16 @@ package pr2.vererbung.vararg_summe;
 
 public class Summator {
 
+    public Summator() {
+        
+    }
+    
+    public int sum(int...a) {
+        int b = 0;
+        for (int i = 0; i < a.length; i++) {
+            b = b + a[i];
+        }
+        return b;
+    }
+    
 }
diff --git a/sources/src/main/java/pr2/vererbung/vararg_summe/test/SummatorTest.java b/sources/src/main/java/pr2/vererbung/vararg_summe/test/SummatorTest.java
index 2b8ab32..6fa32f2 100644
--- a/sources/src/main/java/pr2/vererbung/vararg_summe/test/SummatorTest.java
+++ b/sources/src/main/java/pr2/vererbung/vararg_summe/test/SummatorTest.java
@@ -9,16 +9,16 @@ public class SummatorTest {
 
     @Test
     void testSum() {
-// TODO: Einkommentieren
-//        Summator s = new Summator();
-//        assertEquals(3, s.sum(1, 2));
-//        assertEquals(1, s.sum(-1, 2));
-//        assertEquals(6, s.sum(1, 2, 3));
-//        assertEquals(0, s.sum(1, 2, -3));
-//        assertEquals(10, s.sum(1, 2, 3, 4));
-//        assertEquals(2, s.sum(1, 2, 3, -4));
-//        assertEquals(15, s.sum(1, 2, 3, 4, 5));
-//        assertEquals(5, s.sum(1, 2, 3, 4, -5));
-//        assertEquals(36, s.sum(1, 2, 3, 4, 5, 6, 7, 8));
+
+        Summator s = new Summator();
+        assertEquals(3, s.sum(1, 2));
+        assertEquals(1, s.sum(-1, 2));
+        assertEquals(6, s.sum(1, 2, 3));
+        assertEquals(0, s.sum(1, 2, -3));
+        assertEquals(10, s.sum(1, 2, 3, 4));
+        assertEquals(2, s.sum(1, 2, 3, -4));
+        assertEquals(15, s.sum(1, 2, 3, 4, 5));
+        assertEquals(5, s.sum(1, 2, 3, 4, -5));
+        assertEquals(36, s.sum(1, 2, 3, 4, 5, 6, 7, 8));
     }
 }