Initial Template Which Converts Fahrenheit To Celsius

I am new to Java, programming, and intelliJ. I am trying to make a BMI Calculator using this code as my initial template which converts Fahrenheit to Celsius.

import javax.swing.JFrame;
public class Fahrenheit
{
//-----------------------------------------------------------------
// Creates and displays the temperature converter GUI.
//-----------------------------------------------------------------

[code]....

I created a local field within BMIButtonListener for weight, height, resultLabel, and was able to compile but it did not calculate and listed exceptions.