Answer:

Either, or both. This is a design decision.

Variables

Floating point would probably be best for a real application, but, to simplify things let us:

This work will by done by a FahrConvert object. Here is a sketch of the code:

public class FahrConvert . . .
{  
  int fahrTemp ;  // input from the user: Fahrenheit temperature
  int celsTemp ;  // result: Celsius temperature
  
  public FahrConvert()   // constructor for FahrConvert
  {  
    . . . . .
  }
   
  // The application
  public void convert( )  
  {
    celsTemp = ((fahrTemp-32) * 5) / 9;
  }
   
  public static void main ( String[] args )
  {
     . . . . .
  }
}   

You could continue on from here and develop a non-GUI application where the main() method does input and output with the keyboard and monitor. You might do this if you wanted to debug the application code first before working on the GUI. However, this example will do input and output with GUI components.

QUESTION 3:

Now give some thought to the graphical interface.