Question

Two questions in one, but I have a very short test case demonstrating my problems:

import java.awt.*;
import java.awt.image.*;
import java.io.*;
import java.text.*;
import java.util.*;
import javax.imageio.*;

public class Numbers {

    public static void main(String[] args) throws IOException {
        double[] numbers = { 10000.12, 20000.23, 3000.45 };
        DecimalFormat format = new DecimalFormat("0.00");
        format.setGroupingUsed(false);
        BufferedImage image = new BufferedImage(400, 150, BufferedImage.TYPE_INT_ARGB);
        Graphics2D g2d = image.createGraphics();
        g2d.setColor(Color.BLACK);
        g2d.setBackground(Color.YELLOW);
        g2d.clearRect(0, 0, image.getWidth(), image.getHeight());
        g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
        g2d.setFont(new Font(Font.SANS_SERIF,Font.BOLD, 24));
        FontMetrics metrics = g2d.getFontMetrics();

        for (int i = 0; i < numbers.length; i++) {
            String str = format.format(numbers[i]);
            System.out.println(i + ": " + str);

            int w = metrics.stringWidth(str);
            int h = metrics.getHeight();
            int x = 100 * i;
            g2d.drawString(str, x - w/2, 0);
        }

        g2d.dispose();
        ImageIO.write(image, "PNG", new File("Numbers.png"));
    }
}

When I use it I get:

C:\Temp>javac -version
javac 1.6.0_24

C:\Temp>javac Numbers.java

C:\Temp>java Numbers
0: 10000,12
1: 20000,23
2: 3000,45

and this image produced:

My questions:

1. How to force the DecimalFormat to use dot and not comma, without switching locale?
2. The w seems to be correct, but what is wrong with 0 as the height – why are numbers printed offscreen?

Thank you! Alex

UPDATE:

I’ve ended up using Locale. The str.replace(“.”, “,”) comment is cool too.

import java.awt.*;
import java.awt.image.*;
import java.io.*;
import java.text.*;
import java.util.*;
import javax.imageio.*;

public class Numbers {

    public static void main(String[] args) throws IOException {
        double[] numbers = { 10000.12, 20000.23, 3000.45 };
        BufferedImage image = new BufferedImage(400, 150, BufferedImage.TYPE_INT_ARGB);
        Graphics2D g2d = image.createGraphics();
        g2d.setColor(Color.WHITE);
        g2d.setBackground(Color.GRAY);
        g2d.clearRect(0, 0, image.getWidth(), image.getHeight());
        g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
        g2d.setFont(new Font(Font.SANS_SERIF,Font.BOLD, 24));
        FontMetrics metrics = g2d.getFontMetrics();
        NumberFormat format = NumberFormat.getInstance(Locale.US);
        format.setGroupingUsed(false);
        if (format instanceof DecimalFormat) {
            ((DecimalFormat) format).applyPattern("0.00");
        }

        for (int i = 0; i < numbers.length; i++) {
            String str = format.format(numbers[i]);
            System.out.println(i + ": " + str);

            int w = metrics.stringWidth(str);
            int h = metrics.getHeight();
            int x = 100 * i;
            g2d.drawString(str, x - w/2, h);
        }

        g2d.dispose();
        ImageIO.write(image, "PNG", new File("Numbers.png"));
    }
}

Answer 1

For 1: You can specify the format using format.applyLocalizedPattern("#00.0#"); instead of format.setGroupingUsed(false);

Another option is to use custom format symbols:

DecimalFormatSymbols decimalSymbol = new DecimalFormatSymbols(Locale.getDefault());
decimalSymbol.setDecimalSeparator('.');
format.setGroupingUsed(false);

More information about localized patterns and some examples can be found here:
http://download.oracle.com/javase/tutorial/i18n/format/decimalFormat.html and http://download.oracle.com/javase/tutorial/i18n/format/decimalFormat.html#numberpattern

For your second question, When you use g2d.drawString(str, x, y) the baseline is at x,y not the top left position as when you draw a rectangle. The baseline is basically the bottom of letters like a, b, c. Commas and letters like g, j, y extend below the baseline. You basically need to add the height of the text to the y position where you want to display the text.