How to call value from one jFrame to another

I use netbeans IDE 8.1
I means I create 3 jFrame , one for entering data a=1, b=2 , c=3 , d=4 ,
the second jFrame I want to call the value to use it in some formula e.g. addition . Also, for third jFrame I want to call the vulue for another formula.
Could to help me,,
Thank you