Java Methods

I do not understand Java methods at all. I was told that these were to breakdown code into simpler structures yet all it does for me is make thing that much more difficult. Does anybody know how to use Java methods properly, I looked on the website posted in earlier Java threads for help and found nothing on Java methods. I just wrote a Java program using methods and cannot get the thing to function correctly so if anybody knows any info on these things please drop any information that you have. If you would like to chat sometime that would be fine too, just name it.

 

Hey movement - or anybody else that would know. I had a chance about two weeks ago for some bonus points and didn't do them. I was supposed to write two programs. The instructions are below. Some of you might remember me asking for a Java class for quadratic equations about two weeks ago and that is because that is what one of the programs deals with. Here are the program details and by the way this is without methods. What would the code for these look like? I tried to figure them out but couldn't and are these supposed to be easy because they sure aren't for me. Thanks for any help.

Bonus #1
Write an application that will accept a series of product costs along with the quantity purchased. The program should then display a subtotal of the purchases, the amount of sales tax based on a 6.75% rate, and the total of the purchase in a single dialog message. You should direct the user how to indicate the end of input.
For example, if the input consisted of:

Cost of Product Quantity Purchased
$4.56 2
$5.98 4
$0.95 10
$9.99 5

Your output would look something like:

Your subtotal is $92.49
Sales tax is $6.24
Purchase total is $98.73


Bonus #2
Write an application for the algorithm developed for determining the actual root(s) of a Quadratic Equation using the Quadratic Formula. Your program should display the Quadratic Equation along with the answer(s) or message of no real answers in the output. There should be no assumptions made. If the equation specified is not a Quadratic Equation, your output message should so indicate.

 

BTW: Does anybody know of a free Java compiler that I can download because I am sick of executing these programs through the MS-DOS Prompt Window. That would REALLY help out. Thanks.

 

Yes movement the program is supposed to direct him to enter the information. If you have the code may I ask, what does the code look like? I would like to study it and see what mistakes I was making in the bonus projects. The quadratic equation seemed almost impossible to me.

 

I am having trouble with a while structure in one of my programs.
The while structure is:

while ( choice >= 1 ) ( choice <= 5 )




Which means "while greater than or equal to 1 but less than or equal to 5"

I get this error message though:

Menu.java48: illegal start of expression







What am I doing wrong?

 

OK that worked but why can't I get this program to execute:
If you have a java compiler paste and save this and then try to execute it.



// import Java packages
import javax.swing.JOptionPane;

public class Menu {

// OpeningInfo Method
public static void OpeningInfo ()
{
JOptionPane.showMessageDialog( null, "My name is Jackie Dotson.\nThis program takes two numbers and does the indicated operation.\nThis is program number 9." );
}

// NormalExit Method
public static void NormalExit ()
{
JOptionPane.showMessageDialog( null, "This was a normal program exit, Thank you." );
}

// Menu Method
public static String Menu ()
{
String input; // Input entered
String menu; // Menu entered as String
int choice; // Choice entered as integer

menu = "Choose from one of the choices please:\n\n " + // Menu text
"1. Add two numbers\n2. Subtract two numbers\n " + // Menu text
"3. Multiply two numbers\n4. Divide two numbers\n " + // Menu text
"5. Exit\n\n"; // Menu text

input = JOptionPane.showInputDialog( menu ); // Prompt for number
choice = Integer.parseInt( input );

// While loop
while (( choice >= 1 ) && ( choice <= 5 ))
{
JOptionPane.showMessageDialog( null, "Error, please select again." );

menu = "Choose from one of the choices please:\n\n " + // Menu text
"1. Add two numbers\n2. Subtract two numbers\n " + // Menu text
"3. Multiply two numbers\n4. Divide two numbers\n " + // Menu text
"5. Exit\n\n"; // Menu text

input = JOptionPane.showInputDialog( menu ); // Prompt for number
choice = Integer.parseInt( input );
}
return menu; // Return for menu
}

// Number Method
public static double Number ( String prompt )
{
String input; // Input entered
double number; // Number entered as double

// Prompt for first number
input = JOptionPane.showInputDialog( prompt );
number = Double.parseDouble( input );

return number;
}
}



// Execution of program begins
public static void main ( String args[] )
{

String input; // Input entered
String output; // Output shown
String menu; // Menu attained
int choice; // Choice entered as integer
double number1; // Number entered as double type
double number2; // Number entered as double type
double sum; // Sum type double
double total; // Total type double
double product; // Product type double
double quotient; // Quotient type double

OpeningInfo (); // Information

menu = Menu(); // Initializes menu

// If structures
if ( choice == 1 )
{
sum = number1 + number2; // Sum calculated

// Sum output
JOptionPane.showMessageDialog( null, "The sum is " + sum, "Results",
JOptionPane.PLAIN_MESSAGE );
}

if ( choice == 2 )
{
total = number1 - number2; // Total calculated

// Total output
JOptionPane.showMessageDialog( null, "The total is " + total, "Results",
JOptionPane.PLAIN_MESSAGE );
}

if ( choice == 3 )
{
product = number1 * number2; // Product calculated

// Product output
JOptionPane.showMessageDialog( null, "The product is " + product, "Results",
JOptionPane.PLAIN_MESSAGE );
}

if ( choice == 4 )
{
quotient = number1 / number2; // Quotient calculated

// Quotient output
JOptionPane.showMessageDialog( null, "The quotient is " + quotient, "Results",
JOptionPane.PLAIN_MESSAGE );
}

if ( choice == 5 )
{
NormalExit (); // Normal exit indicated
}



number1 = Number( "Please enter your first number." ); // First number entered by user
number2 = Number( "Please enter your second number." ); // Second number entered by user

System.exit( 0 ); // End
}

 

Also, I have this assignment where you ask the user for a large number and then the number is output but spaced:

If the user entered 1234567

The output would be 1 2 3 4 5 6 7

How would you space the numbers though?

Here is the program to get the number but how do you make the number space out?


import javax.swing.*;

public class Number {

public static void main (String args[] )
{
String input;
long number;

input = JOptionPane.showInputDialog( "Enter a number" );
number = Long.parseLong( input );

JOptionPane.showMessageDialog( null, "The number is " + number, "Result",
JOptionPane.PLAIN_MESSAGE );

System.exit( 0 );
}
}

 

Hey movement, how do you fit the space coding into the coding that I wrote?

What would the input and output look like for this program:

Bonus #2
Write an application for the algorithm developed for determining the actual root(s) of a Quadratic Equation using the Quadratic Formula. Your program should display the Quadratic Equation along with the answer(s) or message of no real answers in the output. There should be no assumptions made. If the equation specified is not a Quadratic Equation, your output message should so indicate.

 

Does anybody know what the code for the spacing of the numbers looks like and how you incorporate it into the program which I have written?