Writing If Statement With Combobox

I'm working on assignment for a class where I'm creating a home utility auditor. Basically the user has to pick from a list of appliances and then input various fields to calculate a total cost. When the user chooses "washer" from the list of appliances, they must enter in values for 2 separate fields, and will then click calculate to get total cost. I've been trying to implement this through an if, else statement, but it's not wanting to calculate a total cost and I'm running into errors. I've put the code below.

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
// The calculate button will multiply the 3 fields that the user inputs:
//cost*Kw used*hours used=total cost of operation
float num1,num2, num3, result;
//now, parse the text to a type float
num1= Float.parseFloat (costField.getText ());

[Code] ......