Simple Graph

[Marcus Senna]

Hey, i am trying to find a way to draw a simple graph in a frame. Your help would be greatly appreciated as i am new to Java Swing. Thanks!!!

[Craig Wood]

import java.awt.*;
import javax.swing.*;
 
public class PlotTest extends JPanel {
    int[] data = { 25, 60, 42, 75 };
    final int PAD = 20;
 
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D)g;
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                            RenderingHints.VALUE_ANTIALIAS_ON);
        int w = getWidth();
        int h = getHeight();
        g2.drawLine(PAD, PAD, PAD, h-PAD);
        g2.drawLine(PAD, h-PAD, w-PAD, h-PAD);
        double xScale = (w - 2*PAD)/(data.length + 1);
        double maxValue = 100.0;
        double yScale = (h - 2*PAD)/maxValue;
        // The origin location.
        int x0 = PAD;
        int y0 = h-PAD;
        g2.setPaint(Color.red);
        for(int j = 0; j < data.length; j++) {
            int x = x0 + (int)(xScale * (j+1));
            int y = y0 - (int)(yScale * data[j]);
            g2.fillOval(x-2, y-2, 4, 4);
        }
    }
 
    public static void main(String[] args) {
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.getContentPane().add(new PlotTest());
        f.setSize(400,400);
        f.setLocation(200,200);
        f.setVisible(true);
    }
}

[Ulf Dittmer]

Craig, that's pretty neat and simple. I've taken the liberty of incorporating it into our FAQ: PlotTest

[mohsin anssari]

Hi ... i seems quite simple code.. but i dont understand whn i try to compile it with eclipse ... an error comes
Java virtual machine launcher
"could not find the main class.Program exits"

can any one can help me with that error am out of my options