At first i just wrote code for increment and decrement button code. Then i tried to connect it with stock. Increment operation working fine.
Then i tried to do it for decrement. I got the issue as i explained above.
increment/decrement code in controller
Cart.java
These are the related codes. Please let me know do i still need to provide more information.
Actually just check my previous thread, they helped me solve the issue and i did it on my own. I am not expecting an spoon feeding here.