Java lab comission

import javax.swing.JOptionPane;
import java.text.DecimalFormat;
public class Commission
{
public static void main(String args[])
{
double dollars, answer;
int empCode;

dollars = getSales();
empCode = getCode();
answer = getComm(dollars,empCode);
output(answer,dollars);
finish();
}


public static double getSales()
{
//delcare
double sales = 0.0;
boolean done = false;
while(!done)
{
String answer = JOptionPane.showInputDialog(null,"Enter the sales amount\n(don't use commas or dollar)\n or click Cancel to exit:");
if(answer == null) finish();
try
{
sales = Double.parseDouble(answer);
if(sales <= 0)throw new NumberFormatException();
else done = true;
}
catch(NumberFormatException e)
{
JOptionPane.showMessageDialog(null,"Your entry was not in the proper format.","Error",JOptionPane.INFORMATION_MESSAGE);
}
}
return sales;

}
public static int getCode()
{
int code = 0;
boolean done = false;
while(!done)
{
try
{
String message = "Enter the commission code :"+"\n\n1)Telephone Sales\n2) Instore Sales\n3) Outside Sales \n\n";
code = Integer.parseInt(JOptionPane.showInputDialog(null,message));
//valid code
if(code<1||code>3) throw new NumberFormatException();
else done = true;
}
catch(NumberFormatException e)
{
JOptionPane.showMessageDialog(null,"Please enter 1,2,3","Error",JOptionPane.INFORMATION_MESSAGE);
}
}
return code;
}

public static double getComm(double employeeSales,int employeeCode)
{
double commission =0.0;
switch(employeeCode)
{
case 1: commission = .10*employeeSales;
break;
case 2: commission = .14*employeeSales;
break;
case 3: commission = .18*employeeSales;
break;
}
return commission;
}

public static void output(double commission,double sales)
{
DecimalFormat twoDigits = new DecimalFormat("$#,000.00");
JOptionPane.showMessageDialog(null,"Your commission on sales of" + twoDigits.format(sales)+" is "+twoDigits.format(commission),"Commission Totals",JOptionPane.INFORMATION_MESSAGE);
}
public static void finish()
{
System.exit(0);
}
}

โพสทำไมไม่บอก แก้ error ตั้งนาน -3-

โอ้ แจ่ม

ถ้าหนูยังเรียนไม่ได้แล้วอยากทำบ้างนี่ต้องทำยังไงคระ?