Java code to find out operative system, : I am very new at coding in Java and I want to write a code to find out my operative system through a dialogue box (Windows 10). I through this code but I am not sure how to completely implement it.

Please let me know what I am doing wrong in simple terms as I am a beginner ;D.

Thank you in advance.[![enter image description here][1]][1] 


  [1]: https://i.stack.imgur.com/WRupV.png