3 replies to this topic

[vctrshowalter]

So my prompt is this:
Design and implement an application that draws a traffic light and uses a push button to change the state of the light. Derive the drawing surface from the JPanel class and use another panel to organize the drawing surface and the button.

I understand well enough how to make buttons and listeners (i think) but the actual drawing of the circles for the light is not working out.

import javax.swing.JFrame;

import javax.swing.*;

import java.awt.*;


public class TrafficLight

{

//-------------------------------------

//Creates the main program frame

//-------------------------------------


public static void main (String[] args)

{


JFrame frame=new JFrame("Traffic Light");

frame.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);


TrafficLightPanel panel = new TrafficLightPanel();


frame.getContentPane().add(new TrafficLightPanel());


frame.pack();

frame.setVisible(true);

}

}

//************************************************************

//	Victoria Showalter		Lab 6a

//	Creates a traffic light.

//************************************************************


import java.awt.*;

import java.awt.event.*;

import javax.swing.*;


public class TrafficLightPanel extends JPanel

{

	private int count;

	private JButton status;

	private JLabel label;


	

	//--------------------------------------------------------

	//	Constructor: Sets up the GUI

	//--------------------------------------------------------

	public TrafficLightPanel ()

	{

		int red = 0;

		int yellow = 1;

		int green = 2;

		

		status = new JButton ("Change!");

		status.addActionListener (new ButtonListener());

		

		label = new JLabel ("Traffic");

		

		add (status);

		add (label);


		setPreferredSize (new Dimension (300,200));

		setBackground (Color.black);


	}

	

	//--------------------------------------------------------

	//	Represents a new listener for button push.

	//--------------------------------------------------------

	private class ButtonListener implements ActionListener

	{

		//----------------------------------------------------

		//	Changes the color of the traffic light when the 

		//	button is pushed.

		//----------------------------------------------------

		public void actionPerformed (ActionEvent event)

		{

			count++;

			count = count % 3; // take the remainder of count/3, yielding 0, 1 or 2.

		}

		

	//--------------------------------------------------------

	//	Draws traffic light

	//--------------------------------------------------------

	public void paintComponent (Graphics page)

		{

			TrafficLightPanel.super.paintComponent (page);

			

		if (count == 0)

			{

				page.setColor(Color.red);

				page.fillOval (20, 30, 50, 65);

			}

		if (count == 1)

			{

				page.setColor(Color.yellow);

				page.fillOval (20, 30, 50, 65);

			}

		if (count == 2)

			{

				page.setColor(Color.green);

				page.fillOval (20, 30, 50, 65);

			}


		page.setColor(Color.white);

		page.drawString("Ready...Set...GO!!!",10,180);

		}


	}

	


}

How do I physically make the traffic light? I have no errors thusfar and it compiles, but only displays a button that says "Change!" on a black screen. Please and thank you

[lethalwire]

It looks like you've accidentally added your paintComponent method inside of your inner class! This should fix your problem. Then you'll be able to see how to fix your lights.

[An Alien]

Do you have prof Darlene? I've got the same assignment. See this thread: http://forum.codecal...rough-help.html

[vctrshowalter]

Yes, I do have prof Darlene! and thank you, I'm fixing it now and I think I can make it work.