@edvin I was able to reproduce your code and to fix my error. However I have a question to your example. Since I need to insert a line in the middle of the list and add the line at the correct position I need somekind of iterator that specifies the position in the list. I created the following code and it works in some way but I get index out of bounds exceptions, I cannot delete in the middle of the array at a specified position and I can not use value += syntax. If you have time to day I look forward to a hint. Than you