Java画余弦曲线，哪里错误了？

ruinjoy 2007-10-16 07:36:18

import java.awt.*;

import java.awt.event.*;

import javax.swing.*;

public class yuxian extends JFrame implements ComponentListener,ItemListener

{

    p rivate JComboBox combobox_color;

    public yuxian()

    {

        super("");

        this.setSize(500,500);

        this.setDefaultCloseOperation(EXIT_ON_CLOSE);

        this.setLayout(new FlowLayout());

        

        Object data[]={Color.red,Color.green,Color.blue};

        combobox_color=new JComboBox(data);

        combobox_color.addItemListener(this);

        this.add(combobox_color);

        

        this.addComponentListener(this);

        this.setVisible(true);

    }

    public void paint(Graphics g)

    {        g.setColor((Color)combobox_color.getSelectedItem());

        double f(double x) 

        {  

          return (Math.cos(x/12.0)*200.0/4+100);  

        }  

        for(int x=0;x<this.getWidth();x++)

        {

            g.drawLine(x,(int)f(x),x+1,(int)f(x+1));

        }

    }

    public void itemStateChanged(ItemEvent e)

    {

        repaint();

    }

    public void componentResized(ComponentEvent e)

    {

        repaint();

    }

    public void componentMoved(ComponentEvent e){}

    public void componentHidden(ComponentEvent e){}

    public void componentShown(ComponentEvent e){}

    public static void main(String arg[])

    {

        new yuxian();

    }

}