Variables

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

• Convert the input string to an int variable.
• Evaluate the formula using integer arithmetic.
• Save the result as an int.

All this work will be done with the methods and variables of a  FahrConvert object. With these decisions made, the application code can be sketched out:

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 )
  {
    FahrConvert fahr  = new FahrConvert() ;
    
    . . . . .
  }   
}   

We could continue on from here and develop a non-GUI application where main() does input and output. You might do this if you wanted to debug the application code before working on the GUI. Now give some thought to the graphical interface.