double casting not producing expected value

Question

I'm trying to use a double that has a very small value to produce one of a more regular size. For example, dividing 1/(double) would produce something like 14.12848572.... I then cast this double into an int to produce a number which I can use to draw an image in a JPanel.

The issue I've been having is that the image does not draw how I expect it to draw. I think this is because there's something I don't understand about how casting doubles works. Anyone who can tell me a bit about how this process actually goes down would be very helpful.

EDIT:
The purpose of this code is translating a monetary value into the size of a bar on a graph. The size of these bars should change as the value changes so that they utilize space in the most efficient manner.

Therefore...

Due to the nature of the monetary values, max will never be less than 430.
I want the image to be bigger the smaller xscale is. If there are fewer values to graph, xscale is smaller, and then the bars are drawn bigger.

EDIT: The following image shows what my program is currently drawing. What I would like to draw is a series of bars on a bar graph. The xscale and associated variables are what I am primarily concerned with right now.

EDIT: The SSCCE is completed (I think)! If you run this code, you will see the drawing I don't want. If you change barwidth to equal 7 or some normal int, you will see something that is more along the lines of what I want drawn. Please let me know if there is anything more I should do to make things easier!

EDIT: Copy/pasted wrong code, has been corrected (derp)

import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;


  public class castingexample extends JPanel
{   
private static int ypoint;
private static int barheight;
private static Color color;

private static int bars = 10;
private static int xpoint = 0;
private static int barwidth = 7;
private static double xscale = 7;
private static int yscaleplus = 10000;
private static int yscaleneg = 0;

public static void main(String[] args)
{
    JFrame frame = new JFrame();
    frame.add(new castingexample());
    frame.setVisible(true);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(500,500);
}

public castingexample()
{   
    new Timer(100, new ActionListener()
    {
        @Override
        public void actionPerformed(ActionEvent e)
        {
            resize();
            repaint();
        }
    }).start();
}

public void resize()
{

        xscale = bars/(800 - bars*5);
        xscale = 1/xscale;
}


public void paintComponent (Graphics g)
{
    super.paintComponent(g);

    for (int i = 0; i < bars; i++)
    {
        barheight = 200;
        barwidth = (int) (xscale);
        ypoint = 450 - barheight;
        xpoint = 105+(barwidth + 5)*i;

        if(ypoint < 450)
            color = Color.green;
        else
            color = Color.red;

        g.setColor(color);
        g.fillRect(xpoint, ypoint, barwidth, barheight);
    }
}

}

Here's some relevant code:

    public void resize()
{
    int max = 0;
    int min = 0;

        for (int i = 0; i < bars; i++)
        {
            if (getTime(i) > max)
                max = (int)getTime(i);
        }
        yscaleplus = max/430;

        /*
        for (int i = (int)(getLife() - getRetire() + 1); i < bars; i++)
        {
            if (getTime(i) < min)
                min = (int)getTime(i);
        }
        yscaleneg = Math.abs(min/200);
        */

        xscale = bars/(800 - bars*5);
        xscale = 1/xscale;
}


public void paintComponent (Graphics g)
{
    super.paintComponent(g);

    g.drawLine(100, 20, 100, 630);
    g.drawLine(100, 450, 900, 450);

    for (int i = 0; i < bars; i++)
    {
        barheight = (int) (getTime(i)/yscaleplus);
        barwidth = (int) (xscale);
        ypoint = 450 - barheight;
        xpoint = 105+(barwidth + 5)*i;

        if(ypoint < 450)
            color = Color.green;
        else
            color = Color.red;

        g.setColor(color);
        g.fillRect(xpoint, ypoint, barwidth, barheight);
    }
}

1) For better help sooner, post an [SSCCE](http://sscce.org/). 2) One way to get image(s) for an example is to hot-link to the images seen in [this answer](http://stackoverflow.com/a/19209651/418556). — Andrew Thompson, Dec 14 '13 at 22:43
Maybe it's me, but I'm just confused by your code snippets. If you could create a small compilable and runnable program that demonstrates just your problem, (as @AndrewThompson has already recommended above), I think many of us would be better equipped to help you. — Hovercraft Full Of Eels, Dec 14 '13 at 22:44
@HovercraftFullOfEels *"Maybe it's me"* No, you're not alone there. The population of 'Confusionville' is at least 2. — Andrew Thompson, Dec 14 '13 at 22:46
if `max` is less than 430, `max/430` will always be 0 because it's an integer division. That may be your issue, in which case you can simply add: `max/430d` to do a double division. — assylias, Dec 14 '13 at 22:48
I am also confused, but you do realize that if `xscale` is lower than 1, then the smaller `xscale` is, the bigger it's gonna get when you do `xscale = 1/xscale`, right? I really don't know what your code does, but this could just mean that the smaller the image should be, the bigger you're actually gonna draw it... — zbr, Dec 14 '13 at 22:49
I'm working on adding more things besides the edits I just made to help you guys help me out. — Christian Baker, Dec 14 '13 at 22:56
-1 for not posting an [sscce](http://sscce.org). The construct is well worth the effort, and so you won't regret creating and posting it. — Hovercraft Full Of Eels, Dec 14 '13 at 23:01
I have no clue how to post an sscce, I'm trying to figure it out, but until then I just posted an image. EDIT: I'm trying to find all the relevant code, but it's taking a little bit. — Christian Baker, Dec 14 '13 at 23:02
Please read the several links you've been given to the [sscce](http://sscce.org) page. They explain what you need. — Hovercraft Full Of Eels, Dec 14 '13 at 23:03
We don't need 'more' stuff. We need *less* stuff. One line of code with the cast in it would do. All this Swing stuff is irrelevant. You need to take @AndrewThompson's advice. — user207421, Dec 14 '13 at 23:17
I'm just gonna kill this page and see if I can figure some more stuff out with the answer that has been provided, which is pretty helpful actually. If I still can't figure it out, I'll post another question with the appropriate formatting and information. Sorry to screw this up so badly, I'm still pretty new to the site. — Christian Baker, Dec 14 '13 at 23:22
No sweat -- you're not screwing anything up, and in fact it looks like you've got your answer. But when you get a chance, do look over the sscce site as you will find it helpful in the future. In fact if done well, the process will help you yourself isolate and solve errors. — Hovercraft Full Of Eels, Dec 15 '13 at 01:54

score 2 · Accepted Answer · answered Dec 14 '13 at 23:14

2

doubles do not store information as you seem to think, they store information as a value followed by an exponential value of 2^x, this removes the capability you are trying to use

take a look at Math.round(x) instead.

answered Dec 14 '13 at 23:14

Kent

713
2
8
19

What capability does it remove exactly? The ability to turn a very small value into a moderately sized one, or the ability to round that moderately sized value? – Christian Baker Dec 14 '13 at 23:17
as you tend towards smaller -or- larger numbers, double values become less accurate, leading to what you see here. – Kent Dec 14 '13 at 23:19
Should I use float or long instead? Or do those suffer from the same issues? – Christian Baker Dec 14 '13 at 23:23
long, int, short, & byte store information in integer format float & double store information in floating-point format again, take a look at Math.round() it should work well in this case – Kent Dec 14 '13 at 23:34

double casting not producing expected value

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