Need Java help with graphics2d

[ROAD_DOGG33J]

The program has to draw 15 lines of different color, length and thickness using Line2D.Double.
However, when I run the program no lines are drawn, so I need help with that.

Here is the LinePanel file:

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

class LinePanel extends JPanel
{
	int numberOfLines;
	int maxLength;
	Random generator;
	
	public LinePanel(int lines, int maxL)
	{
		super();
		numberOfLines = lines;
		maxLength = maxL;
	}
	
	
	public void draw(Graphics g)
	{
		System.out.println("running draw");
		generator = new Random();
		
		Line2D.Double [] lines = new Line2D.Double[15];
				
		Graphics2D g2 = (Graphics2D)g;
		
		for(int x = 0; x< numberOfLines; x++)
		{
			lines[x] = new Line2D.Double(x + 20, x + 10, x+20, generator.nextInt(maxLength));				
		}
		
		for(int x = 0 ; x< numberOfLines; x++)
		{
			g2.setColor(new Color(generator.nextInt(256),generator.nextInt(256),generator.nextInt(256)));
         	g2.setStroke(new BasicStroke(generator.nextInt(5)));
         	g2.draw(lines[x]);
		}	   
		
		g2.draw(new Line2D.Double(10,35,65,56));
		
	}
}

Here is the Lines file:

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


public class Lines extends JFrame
{
	// Variables declaration
	private JButton cmdDraw;
	private JPanel contentPane;
	LinePanel drawingPanel;
	// End of variables declaration


	public Lines()
	{
		super("Title");
		initializeComponent();
		//
		// TODO: Add any constructor code after initializeComponent call
		//

		this.setVisible(true);
	}

	/**
	 * This method is called from within the constructor to initialize the form.
	 * WARNING: Do NOT modify this code. The content of this method is always regenerated
	 * by the Windows Form Designer. Otherwise, retrieving design might not work properly.
	 * Tip: If you must revise this method, please backup this GUI file for JFrameBuilder
	 * to retrieve your design properly in future, before revising this method.
	 */
	private void initializeComponent()
	{
		
		drawingPanel = new LinePanel(15, 200);
		this.getContentPane().add(drawingPanel,BorderLayout.CENTER);
		cmdDraw = new JButton();
		contentPane = (JPanel)this.getContentPane();

		//
		// cmdDraw
		//
		cmdDraw.setText("Draw Lines");
		cmdDraw.setMaximumSize(new Dimension(90, 25));
		cmdDraw.setMinimumSize(new Dimension(90, 25));
		cmdDraw.setPreferredSize(new Dimension(90, 25));
		cmdDraw.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e)
			{
				cmdDraw_actionPerformed(e);
			}

		});
		//
		// contentPane
		//
		contentPane.setLayout(null);
		addComponent(contentPane, cmdDraw, 2,300,390,25);
		//
		// Lines
		//
		this.setTitle("Lines");
		this.setLocation(new Point(0, 0));
		this.setSize(new Dimension(400, 350));
	}

	/** Add Component Without a Layout Manager (Absolute Positioning) */
	private void addComponent(Container container,Component c,int x,int y,int width,int height)
	{
		c.setBounds(x,y,width,height);
		container.add(c);
	}

	//
	// TODO: Add any appropriate code in the following Event Handling Methods
	//
	private void cmdDraw_actionPerformed(ActionEvent e)
	{
		drawingPanel.draw(drawingPanel.getGraphics());
		System.out.println("\ncmdDraw_actionPerformed(ActionEvent e) called.");
		// TODO: Add any handling code here

	}

//============================= Testing ================================//
//=                                                                    =//
//= The following main method is just for testing this class you built.=//
//= After testing,you may simply delete it.                            =//
//======================================================================//
	public static void main(String[] args)
	{
		JFrame.setDefaultLookAndFeelDecorated(true);
		JDialog.setDefaultLookAndFeelDecorated(true);
		try
		{
			UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
		}
		catch (Exception ex)
		{
			System.out.println("Failed loading L&F: ");
			System.out.println(ex);
		}
		new Lines();
	}
//= End of Testing =


}

 

[skip0110]

In LinePanel.java, you need to overload "paint(Graphics g)" not "draw(Graphics g)", and cast the Graphics paseed into paint to Graphics2D.

 

[ROAD_DOGG33J]

In LinePanel.java, you need to overload "paint(Graphics g)" not "draw(Graphics g)", and cast the Graphics paseed into paint to Graphics2D.

I tried the paint thing, but aren't the graphics already cast into Graphics2D?

 

[skip0110]

In JDK 1.2 and above, the JRE will pass a Graphics2D object to paint, but you must cast it down to be able to access any Graphics2D functionality. Like below

public void paint(Graphics g) {
   Graphics2D g2d = (Graphics2D) g;
   g2d.draw(...
   ....
}

Such a cast will throw an Exception in an older JRE.

 

[ROAD_DOGG33J]

I got rid of the lines file and just used JFrame.