Hi,
You have heard correctly, Java is more secure, if and only if application is developed securely.
I have 4 year of experience for developing billing solution web application.
If you are interested let me.
I am not wrong, you need to develop eCommerce site to sell your product, which will have product upload, discount, coupons, category, cart, payment gateway integration like features. Is it so? If yes, I suggest not to go with Java, as it is not fully built for such applications, as per my experience. You can go with BigCommerce, Shopify etc which are also, and easy to manage,
Finally, If you are interested, I can do both Java Development and Shopify/BigCommerce Application development.
Thanks..