How to make chart

import java.awt.*;
import javax.swing.*;

class ChartPanel extends JPanel
{ public ChartPanel(double[] v, String[] n, String t)
{ names = n;
values = v;
title = t;
}

public void paintComponent(Graphics g)
{ super.paintComponent(g);
if (values == null || values.length == 0) return;
int i;
double minValue = 0;
double maxValue = 0;
for (i = 0; i < values.length; i++) { if (minValue > values[i]) minValue = values[i];
if (maxValue < values[i]) maxValue = values[i]; } Dimension d = getSize(); int clientWidth = d.width; int clientHeight = d.height; int barWidth = clientWidth / values.length; Font titleFont = new Font("SansSerif", Font.BOLD, 20); FontMetrics titleFontMetrics = g.getFontMetrics(titleFont); Font labelFont = new Font("SansSerif", Font.PLAIN, 10); FontMetrics labelFontMetrics = g.getFontMetrics(labelFont); int titleWidth = titleFontMetrics.stringWidth(title); int y = titleFontMetrics.getAscent(); int x = (clientWidth - titleWidth) / 2; g.setFont(titleFont); g.drawString(title, x, y); int top = titleFontMetrics.getHeight(); int bottom = labelFontMetrics.getHeight(); if (maxValue == minValue) return; double scale = (clientHeight - top - bottom) / (maxValue - minValue); y = clientHeight - labelFontMetrics.getDescent(); g.setFont(labelFont); for (i = 0; i < values.length; i++) { int x1 = i * barWidth + 1; int y1 = top; int height = (int)(values[i] * scale); if (values[i] >= 0)
y1 += (int)((maxValue - values[i]) * scale);
else
{ y1 += (int)(maxValue * scale);
height = -height;
}

g.setColor(Color.red);
g.fillRect(x1, y1, barWidth - 2, height);
g.setColor(Color.black);
g.drawRect(x1, y1, barWidth - 2, height);
int labelWidth
= labelFontMetrics.stringWidth(names[i]);
x = i * barWidth + (barWidth - labelWidth) / 2;
g.drawString(names[i], x, y);
}
}

private double[] values;
private String[] names;
private String title;
}

public class Chart extends JApplet
{ public void init()
{ String v = getParameter("values");
if (v == null) return;
int n = Integer.parseInt(v);
double[] values = new double[n];
String[] names = new String[n];
int i;
for (i = 0; i < n; i++)
{ values[i] = Double.parseDouble
(getParameter("value_" + (i + 1)));
names[i] = getParameter("name_" + (i + 1));
}

Container contentPane = getContentPane();
contentPane.add(new ChartPanel(values, names,
getParameter("title")));
}
}