According to Leepoint.net, a simple java program is required to run a simple calculator. The program required is divided into two source files that allows the simple calculator to function.
As experienced Java programmers know, the first source file that allows the simple calculator to run is Calc.java which is a subclass of a JFrame and contains a moderately small main program. Calc.java also builds what is known as the user interface, or the part that of the calculator that is visible, as well as the "controller" that allows the buttons to work. The second source file, known as Calclogic.java, is responsible for making the actual calculations happen.