diff --git a/src/main/java/device/cdPlayer/CD.java b/src/main/java/device/cdPlayer/CD.java
index 4934ac2..ae8f7e8 100644
--- a/src/main/java/device/cdPlayer/CD.java
+++ b/src/main/java/device/cdPlayer/CD.java
@@ -4,6 +4,7 @@ public class CD {
     private String format;
     private String albumName;
     private String[] playList;
+    private String id;
 
     public CD() {}
 
@@ -16,6 +17,13 @@ public class CD {
         this.playList = playList;
     }
 
+    public CD(String format, String albumName, String[] playList, String id) {
+        this.format = format;
+        this.albumName = albumName;
+        this.playList = playList;
+        this.id = id;
+    }
+
     public String getFormat() {
         return format;
     }
@@ -39,4 +47,12 @@ public class CD {
     public void setAlbumName(String albumName) {
         this.albumName = albumName;
     }
+
+    public String getId() {
+        return id;
+    }
+
+    public void setId(String id) {
+        this.id = id;
+    }
 }
diff --git a/src/main/java/device/cdPlayer/CDPlayer.java b/src/main/java/device/cdPlayer/CDPlayer.java
index a60009a..8d4a53b 100644
--- a/src/main/java/device/cdPlayer/CDPlayer.java
+++ b/src/main/java/device/cdPlayer/CDPlayer.java
@@ -152,7 +152,17 @@ public class CDPlayer implements Device {
             throw new MaxCapacityExceededException();
         }
         cdWechseler.loadOneCD(cd,index);
-        System.out.println(index);
+        this.loadedCD=cdWechseler.getCDList().get(0);
+    }
+    public void changeToNextCD(){
+        if(activeSource.equals("CDDrive")){
+            throw new ChangeCDOnlyOnCDWechselerException();
+        }
+
+        List<CD> CDList = cdWechseler.getCDList();
+        int indexOfLoadedCD=CDList.indexOf(loadedCD);
+        int nextIndex=(indexOfLoadedCD+1)%CDList.size();
+        this.loadedCD=CDList.get(nextIndex);
     }
 
     //Getters, Setters und SupportMethods
diff --git a/src/main/java/device/cdPlayer/CDWechseler.java b/src/main/java/device/cdPlayer/CDWechseler.java
index 0ae54e5..fca17d6 100644
--- a/src/main/java/device/cdPlayer/CDWechseler.java
+++ b/src/main/java/device/cdPlayer/CDWechseler.java
@@ -4,7 +4,7 @@ import java.util.ArrayList;
 import java.util.List;
 
 public class CDWechseler {
-    private CD[]CDList=new CD[10];
+    private List<CD> CDList=new ArrayList<>();
     private boolean running=false;
 
 
@@ -16,11 +16,11 @@ public class CDWechseler {
         this.running = true;
     }
 
-    public CD[] getCDList() {
+    public List<CD> getCDList() {
         return CDList;
     }
 
-    public void loadOneCD(CD cd,int index){
-        CDList[index]=cd;
+    public void loadOneCD(CD cd, int index){
+        CDList.add(cd);
     }
 }
diff --git a/src/main/java/device/cdPlayer/exceptions/ChangeCDOnlyOnCDWechselerException.java b/src/main/java/device/cdPlayer/exceptions/ChangeCDOnlyOnCDWechselerException.java
new file mode 100644
index 0000000..ab81555
--- /dev/null
+++ b/src/main/java/device/cdPlayer/exceptions/ChangeCDOnlyOnCDWechselerException.java
@@ -0,0 +1,7 @@
+package device.cdPlayer.exceptions;
+
+public class ChangeCDOnlyOnCDWechselerException extends RuntimeException{
+    public ChangeCDOnlyOnCDWechselerException(){
+        super("Change to next CD olny when CDWechseler is selected");
+    }
+}
diff --git a/src/test/java/device/cdPlayer/CDPlayerTest.java b/src/test/java/device/cdPlayer/CDPlayerTest.java
index 1eb3043..a3e3ebf 100644
--- a/src/test/java/device/cdPlayer/CDPlayerTest.java
+++ b/src/test/java/device/cdPlayer/CDPlayerTest.java
@@ -404,7 +404,7 @@ class CDPlayerTest {
         if(cases.equals("Case3")) {
             _cdPlayer.changePlaySource();
             _cdPlayer.loadCDWechseler(cd,0);
-            CD firstCD=_cdPlayer.getCdWechseler().getCDList()[0];
+            CD firstCD=_cdPlayer.getCdWechseler().getCDList().get(0);
             assertThat(firstCD).describedAs(testName).isNotEqualTo(null);
         }
         if(cases.equals("Case4")) {
@@ -428,5 +428,69 @@ class CDPlayerTest {
         );
     }
 
+    @ParameterizedTest
+    @MethodSource("changeToNextCDData")
+    void changeToNextCDTest(String testName,String cases, CDPlayer _cdPlayer,Exception exception) {
+        if(cases.equals("Case1")) {
+            Exception newException = assertThrows(exception.getClass(), () -> _cdPlayer.changeToNextCD());
+            assertEquals(ChangeCDOnlyOnCDWechselerException.class, newException.getClass());
+        }
+        if(cases.equals("Case2")) {
+            CD actualCD=_cdPlayer.getCD();
+            _cdPlayer.changeToNextCD();
+            CD nextCD=_cdPlayer.getCD();
+            assertThat(nextCD).describedAs(testName).isNotEqualTo(null);
+        }
+        if(cases.equals("Case3")) {
+            CD actualCD=_cdPlayer.getCD();
+            _cdPlayer.changeToNextCD();
+            CD nextCD=_cdPlayer.getCD();
+            assertThat(nextCD.getId()==actualCD.getId()).describedAs(testName).isNotEqualTo(true);
+        }
+        if(cases.equals("Case4")) {
+            CD actualCdBefore=_cdPlayer.getCD();
+            for (int i = 0; i <3 ; i++) {
+                _cdPlayer.changeToNextCD();
+            }
+            CD actualCdAfter=_cdPlayer.getCD();
+            assertThat(actualCdBefore.getId()==actualCdAfter.getId()).describedAs(testName).isEqualTo(true);
+        }
+    }
+    static Stream<Arguments> changeToNextCDData () {
+        String[] audioPlayList=new String[]{"Audio 01","Audio 02","Audio 03","Audio 04","Audio 05"};
+        CD audioCD1=new CD("Audio","PopMusic",audioPlayList,"XAc20044");
+        CD audioCD2=new CD("Audio","RockMusic",audioPlayList,"BLXPP78");
+        CD audioCD3=new CD("Audio","SalsaMusic",audioPlayList,"KKRP118");
+
+        CDPlayer cdPlayer1 = new CDPlayer();
+
+        CDPlayer cdPlayer2 = new CDPlayer();
+        cdPlayer2.changePlaySource();
+        cdPlayer2.loadCDWechseler(audioCD1,0);
+        cdPlayer2.loadCDWechseler(audioCD2,1);
+        cdPlayer2.loadCDWechseler(audioCD3,2);
+
+
+        CDPlayer cdPlayer3 = new CDPlayer();
+        cdPlayer3.changePlaySource();
+        cdPlayer3.loadCDWechseler(audioCD1,0);
+        cdPlayer3.loadCDWechseler(audioCD2,1);
+        cdPlayer3.loadCDWechseler(audioCD3,2);
+
+        CDPlayer cdPlayer4 = new CDPlayer();
+        cdPlayer4.changePlaySource();
+        cdPlayer4.loadCDWechseler(audioCD1,0);
+        cdPlayer4.loadCDWechseler(audioCD2,1);
+        cdPlayer4.loadCDWechseler(audioCD3,2);
+
+        return Stream.of(
+                Arguments.of("[changeToNextCD() by CDWechselerNotSelected ] => shouldThrowAnException", "Case1", cdPlayer1,new ChangeCDOnlyOnCDWechselerException()),
+                Arguments.of("[changeToNextCD()  checking the effect ] => loadedCDShouldNotReturnNull", "Case2", cdPlayer2,null),
+                Arguments.of("[changeToNextCD()  checking the effect 2 ] => loadedCDShouldNotHaveTheSameIdAsPrev", "Case3", cdPlayer3,null),
+                Arguments.of("[3x changeToNextCD()  changing from last to first CD] => FirstCDShouldBeTaken", "Case4", cdPlayer4,null)
+        );
+    }
+
+
 
     }
\ No newline at end of file