I didn't say not to use that method. I'm saying you need to study how it works and use it correctly.
You say you want to add something to a total based on what's selected. That's fine, but that doesn't mean that method knows anything about that. You can't just pass a number to a method that takes no arguments and expect it to magically know what you want it to do with that number.
You said:
Then when check boxes are selected and a button is pressed the selected check box's values will be added to make a total.
all the "if" statements are check boxes, sml, med, lrg, etc.
Before you try to write code, you should spell out that process in complete, precise detail in English and/or psuedocode, without regard to
Java's syntax or API, but keeping in mind that if you do it right--that is if you're precise enough and your steps are simple enough--it will be easy to translate directly to Java.