Need help debugging my java assignment

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Java

import javax.swing.JOptionPane;


public class Text

	{
		public static void main(String[] args)
		{
		String amount;
		double stateSalesTax;
		double countySalesTax;
		double totalSalesTax;
		double totalSalesAmount;
		double amt;
		JOptionPane.showInputDialog("Enter the amount of purchase");
		amt = Double.parseDouble(amount);
		
		stateSalesTax = 0.055;
		countySalesTax = 0.02;
		totalSalesTax = stateSalesTax + countySalesTax;
		totalSalesAmount = amt + totalSalesTax;
		
		JOptionPane.showMessageDialog (null, "The purchase amount is: " + amt + 
										"The state sales tax is:" + stateSalesTax + 
										"The county sales tax is:" + countySalesTax +
										"The total amount of sales is:" + totalSalesAmount);
		}
	}

Command prompt tells me my problem is on the line that reads amt = Double.parseDouble(amount);

What I have tried:

I have tried to use a cast operator to tell the program that the string type can coexist with the double type, but alas, it was to no avail.

Posted 10-Oct-16 12:14pm

Member 12786304

Updated 10-Oct-16 21:39pm

CPallini

v2

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[no name] 10-Oct-16 18:18pm

What "problem" are you talking about? We can't see your screen from here. amount is probably null. null is not a double.

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Patrice T · Answer 1 · 2016-10-10T13:01:00

Use the debugger to see what is the value of amount at error position.

Quote:
I have tried to use a cast operator to tell the program that the string type can coexist with the double type, but alas, it was to no avail.

Obviously, you don't understand how it works, further study is in order.

You should learn to use the debugger as soon as possible. Rather than guessing what your code is doing, It is time to see your code executing and ensuring that it does what you expect.

The debugger allow you to follow the execution line by line, inspect variables and you will see that there is a point where it stop doing what you expect.
Debugger - Wikipedia, the free encyclopedia[^]
Mastering Debugging in Visual Studio 2010 - A Beginner's Guide[^]
http://docs.oracle.com/javase/7/docs/technotes/tools/windows/jdb.html[^]
https://www.jetbrains.com/idea/help/debugging-your-first-java-application.html[^]

The debugger is here to show you what your code is doing and your task is to compare with what it should do.

Amol Wankhede · Answer 2 · 2016-10-10T14:24:00

Here is working code.
Two errors amount is not defined and second thing is that you need to import javax.swing.JOptionPane;

Java

<pre lang="java">
import javax.swing.JOptionPane;

public class Text {

    public static void main(String[] args) {
        String amount;
        double stateSalesTax;
        double countySalesTax;
        double totalSalesTax;
        double totalSalesAmount;
        double amt;
        amount = JOptionPane.showInputDialog("Enter the amount of purchase");
        amt = Double.parseDouble(amount);

        stateSalesTax = 0.055;
        countySalesTax = 0.02;
        totalSalesTax = stateSalesTax + countySalesTax;
        totalSalesAmount = amt + totalSalesTax;

        JOptionPane.showMessageDialog(null, "The purchase amount is: " + amt
                + "The state sales tax is:" + stateSalesTax
                + "The county sales tax is:" + countySalesTax
                + "The total amount of sales is:" + totalSalesAmount);
    }
}

Need help debugging my java assignment

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