How to catch errors in java?

Question

I created a basic binary calculator that has two inputs however, i have a problem. what if the user accidentally entered a symbol sign like ? + ( ) and more. how to prevent this?

heres my code:
https://code.sololearn.com/cp1Due5742B4/?ref=app

please open my code using netbeans or eclipse or whatever. i really need help for this.

Answer 1

Hope this can help you
https://www.sololearn.com/learn/Java/2175/