Can you help me plzzz with a graph?

[dorjee gyaltsen]

hi!
can anyone give me the basic java code to create a simple line graph for output of my java program.
thanks a lot in advance.
cheers!

[Craig Wood]

This is a modification to some older code and should run okay in j2se 1.4
If using j2se 1.5 try compiling to an earlier version with the source flag, eg,

    >javac -source 1.4 simplelinegraph.java

import java.awt.*;
import java.awt.font.*;
import java.awt.geom.*;
import java.util.*;
import java.util.List;
import javax.swing.*;
 
public class SimpleLineGraph
{
    public SimpleLineGraph()
    {
        float[] data = {
            100f, 220f, 12.9f, 65f, 47.3f, 175f, 190f, -18f
        };
        Plotter plotter = new Plotter();
        for(int j = 0; j < data.length; j++)
            plotter.plot(data[j]);
        JFrame f = new JFrame("Plot +/- Values");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.add(plotter);
        f.pack();
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }
 
    public static void main(String[] args)
    {
        new SimpleLineGraph();
    }
}
 
class Plotter extends JPanel
{
    final double PAD = 30.0;
    Font font;
    List dataList;
 
    public Plotter()
    {
        font = new Font("dialog", Font.PLAIN, 14);
        dataList = new ArrayList();
        setBackground(Color.white);
        setPreferredSize(new Dimension(600,400));
    }
 
    public void paintComponent(Graphics g)
    {
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D)g;
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                            RenderingHints.VALUE_ANTIALIAS_ON);
        g2.setFont(font);
        double width = getWidth();
        double height = getHeight();
        double xStep = (width - 2*PAD)/(dataList.size() - 1);
 
        // scale data
        double max = ((Double)Collections.max(dataList)).doubleValue();
        double min = ((Double)Collections.min(dataList)).doubleValue();
        double vertSpace = height - 2*PAD;
        double yOffset = height - PAD;
        double yDataOffset = (min >= 0 ? min : max > 0 ? 0 : max);
        double scale = vertSpace/(max - min);
        double yOrigin = yOffset +
                            (min > 0 ? 0 : max > 0 ? scale * min : - vertSpace);
 
        // draw ordinate
        g2.draw(new Line2D.Double(PAD, PAD, PAD, yOffset));
 
        // label ordinate limits
        g2.drawString(String.valueOf(max), 10, (float)(PAD - 10));
        g2.drawString(String.valueOf(min), 10, (float)(yOffset + PAD*2/3));
 
        // draw abcissa
        g2.draw(new Line2D.Double(PAD, yOrigin, width - PAD, yOrigin));
 
        // abcissa tick marks
        FontRenderContext frc = g2.getFontRenderContext();
        double textWidth = font.getStringBounds("8", frc).getWidth();
        LineMetrics lm = font.getLineMetrics("8", frc);
        double textHeight = lm.getHeight();
        double x = PAD + xStep;
        double y = yOrigin;
        for(int j = 1; j < dataList.size(); j++)
        {
            g2.draw(new Line2D.Double(x, y, x, y + 3));
            x += xStep;
        }
 
        // label abcissa
        String s;
        double sx = PAD + xStep - textWidth/2;
        float sy = (float)(yOrigin + textHeight);
        for(int j = 1; j < dataList.size(); j++)
        {
            s = String.valueOf(j + 1);
            g2.drawString(s, (float)sx, sy);
            sx += xStep;
        }            
 
        // plot data 
        x = PAD;
        double lastX = 0, lastY = 0, value;
        for(int j = 0; j < dataList.size(); j++)
        {
            value = ((Double)dataList.get(j)).doubleValue();
            y = yOrigin - scale * (value - yDataOffset);
            g2.setPaint(Color.red);
            g2.draw(new Ellipse2D.Double(x - 2, y - 2, 4, 4));
            if( j > 0)
            {
                g2.setPaint(Color.black);
                g2.draw(new Line2D.Double(lastX, lastY, x, y));
            }
            lastX = x;
            lastY = y;
            x += xStep;
        }
    }
 
    protected void plot(double input)
    {
        dataList.add(new Double(input));
        repaint();
    }
}