diff --git a/src/org/eidecker/oca8lernen/general/DoubleImplementsClash.java b/src/org/eidecker/oca8lernen/general/DoubleImplementsClash.java
index 86acbe2..935599e 100644
--- a/src/org/eidecker/oca8lernen/general/DoubleImplementsClash.java
+++ b/src/org/eidecker/oca8lernen/general/DoubleImplementsClash.java
@@ -34,6 +34,8 @@ class InterfaceImplementer extends AbstractClass implements SuperInterface1, Sup
 		methode(1, 2, 3);
 		int [] ints = {1,2,3};
 		methode(ints);
+
+		System.out.println(new StringBuilder("Hallo").toString());
 	}
 
 	@Test
diff --git a/src/org/eidecker/oca8lernen/lastminute/Kleinigkeiten.java b/src/org/eidecker/oca8lernen/lastminute/Kleinigkeiten.java
index af3f939..c0db8a5 100644
--- a/src/org/eidecker/oca8lernen/lastminute/Kleinigkeiten.java
+++ b/src/org/eidecker/oca8lernen/lastminute/Kleinigkeiten.java
@@ -3,8 +3,10 @@ package org.eidecker.oca8lernen.lastminute;
 import org.eidecker.oca8lernen.lastminute.hilfspackage.KlasseInEinemAnderenPackage;
 import org.junit.jupiter.api.Test;
 
+import java.io.Serializable;
 import java.util.Arrays;
 import java.util.List;
+import java.util.concurrent.ThreadFactory;
 
 public class Kleinigkeiten {
 
@@ -33,6 +35,15 @@ public class Kleinigkeiten {
 		}
 	}
 
+	@Test
+	public void testCast() {
+		Oberklasse oberklasse;
+		KlasseInEinemAnderenPackage unterklasse = new KlasseInEinemAnderenPackage();
+
+		oberklasse = (KlasseInEinemAnderenPackage) unterklasse;
+
+	}
+
 
 }
 
@@ -41,3 +52,15 @@ abstract class AbstrakteKlasse {
 	// private abstract verboten (auch sinnlos)
 	/* private */ abstract void sinnloseDefinition();
 }
+
+interface MySuperInterface extends Serializable, ThreadFactory {
+	default void m1() {
+
+	}
+}
+
+interface MyOtherSuperInterface {
+	default void m1() {
+
+	}
+}
diff --git a/src/org/eidecker/oca8lernen/lastminute/castbaeume/Baum.java b/src/org/eidecker/oca8lernen/lastminute/castbaeume/Baum.java
new file mode 100644
index 0000000..0fe2deb
--- /dev/null
+++ b/src/org/eidecker/oca8lernen/lastminute/castbaeume/Baum.java
@@ -0,0 +1,31 @@
+package org.eidecker.oca8lernen.lastminute.castbaeume;
+
+import org.junit.jupiter.api.Test;
+
+public class Baum {
+
+	@Test
+	public void testGraphCast() {
+		I i = new C();
+		I i2 = (C)new A();
+		I2 i3 = (C)new A();
+		I2 i4 = (C)new B();
+	}
+}
+
+
+/*
+	A
+	|
+	B-I
+	|
+	C-I2
+ */
+interface I {}
+interface I2 {}
+
+class A {}
+
+class B extends A implements I {}
+
+class C extends B implements I2 {}
\ No newline at end of file
diff --git a/src/org/eidecker/oca8lernen/lastminute/castbaeume/Graph.java b/src/org/eidecker/oca8lernen/lastminute/castbaeume/Graph.java
new file mode 100644
index 0000000..628c51f
--- /dev/null
+++ b/src/org/eidecker/oca8lernen/lastminute/castbaeume/Graph.java
@@ -0,0 +1,25 @@
+package org.eidecker.oca8lernen.lastminute.castbaeume;
+
+import org.junit.jupiter.api.Test;
+
+public class Graph {
+
+	@Test
+	public void testSomeCasts() {
+		D f = new F();
+		E e;
+		e = (E)f;
+	}
+
+}
+
+/*
+	D
+	|-----
+	|    |
+	E    F
+ */
+
+class D {}
+class E extends D {}
+class F extends D {}
\ No newline at end of file