//this shows how to convert string to upper case

    private void btnOKActionPerformed(java.awt.event.ActionEvent evt)                                      
    {                                          
            //---now decide the sales tax rate based upon the state they chose
            // be sure to include break statements when you are finished with the case blocks!
            double salesTaxRate = 0;

            
            String stateChosen = txtState.getText().toUpperCase();  //control for caps/lower case

            switch (stateChosen)                //the thing we are testing
            {
                case "CA":
                    salesTaxRate = .08;
                    break;
                
                case "AZ":                          //here, AZ and NM are the same rate. We say AZ falls through (no break)
                case "NM":    
                    salesTaxRate = .05;
                    break;
                case "NV":
                    salesTaxRate = .01;
                    break;

                case "OR":
                    salesTaxRate = .06;
                    break;

                default:                                //optional but a good idea to include it!
                     JOptionPane.showMessageDialog(this,
                        "Please enter CA, AZ, OR, NV", "Ron's Place", JOptionPane.INFORMATION_MESSAGE);
                       
                    break;
                  
            }