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Thread: Help me out with my code

  1. #1
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    Post Help me out with my code

    I have to display traffic lights and run dialog boxes. When I do this I get the dialog boxes to appear properly but my traffic light stays green for the whole thing, instead of going red, yellow, green. I feel I am pretty close with my code and I just think maybe I'm using repaint wrong or have to do something with the setColor. Here is my working code so far.

    //Import JComponent Graphics, Graphic2D, Color
    import java.awt.Color;
    import java.awt.Graphics;
    import java.awt.Graphics2D;
    import java.awt.Rectangle;
    import java.awt.geom.Ellipse2D;
    import java.awt.geom.Line2D;
    import javax.swing.JComponent;
    import javax.swing.JOptionPane;
     
    public class TrafficLight extends JComponent
    {
       private Color lightColor;
       private int radius;
       private int x;
       private int y;
     
     /* public TrafficLight(Color lightColor, int radius, int x, int y)
       {
       this.lightColor = lightColor;
       this.radius = radius;
       this.x = x;
       this.y = y;
       }*/
     
       public void paintComponent(Graphics g)
       {
       //convert g to graphics 2d and use to draw ellipse for circle.
       //set color to lightColor
           Graphics2D g2 = (Graphics2D) g;
            Rectangle box = new Rectangle(0,0,300,400);
            g2.setColor(lightColor.WHITE);
            g2.fill(box);    
     
            Ellipse2D.Double redRing = new Ellipse2D.Double(35,75,200,200);
            g2.setColor(lightColor.RED);
            g2.draw(redRing);
            g2.fill(redRing);
            validate();
            repaint(); 
     
           Ellipse2D.Double yellowRing = new Ellipse2D.Double(35,75,200,200);
            g2.setColor(lightColor.YELLOW);
            g2.draw(yellowRing);
            g2.fill(yellowRing);
            validate();
            repaint();
     
     
     
            Ellipse2D.Double greenRing = new Ellipse2D.Double(35,75,200,200);
            g2.setColor(lightColor.GREEN);
            g2.draw(greenRing);
            g2.fill(greenRing);
            validate();
            repaint();
     
     
     
     
            /* Rectangle body = new Rectangle(x, y + 10, 60, 10);      
             Ellipse2D.double redLight = new Ellipse2D.double(x + 40, y + 20, radius + 10, 10, 10);
             Ellipse2D.Double yellowLight 
               = new Ellipse2D.Double(x + 40, y + 20, radius + 10, 10, 10);
             Ellipse2D.Double greenLight 
               = new Ellipse2D.Double(x + 40, y + 20, radius + 10, 10, 10);*/
      }
     
       public void setColor(Color newLightColor)
       {
         lightColor = newLightColor;
          //return lightColor;
          //newLightColor = lightColor.YELLOW;
     
     
       }
       }



    //Traffic Light viewer
    import javax.swing.JFrame;
    import javax.swing.JOptionPane;
     
    public class TrafficLightViewer
    {
       public static void main(String[] args)
       {
     
          JFrame LightVisible = new JFrame();
          LightVisible.setSize(400,400);
          LightVisible.setTitle("Traffic Lights");
          LightVisible.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          TrafficLight TrafficViewerOne = new TrafficLight();
         JOptionPane.showMessageDialog(null,"Ready!");
         //LightVisible.setColor(TrafficViewerOne);
         //LightVisible.setColor(redRing);
          LightVisible.add(TrafficViewerOne);
           LightVisible.setVisible(true);
     
     
         JOptionPane.showMessageDialog(null,"Set!");
         JOptionPane.showMessageDialog(null,"Go!");
        }
     
    }

    Any help is much appreciated, just need some advice in the right direction. It's almost like there should be stop and then repaint the color but I don't know how to this. Do I have to place the showMessageDialog code in a certain spot. Thanks for your time.


  2. #2
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    Default Re: Help me out with my code

    Traffic lights don't go red, yellow, green, but I'll assume that the requirements are dictated by the assignment.

    You have all of the necessary elements, some of them unused, others used incorrectly. I'm not going to show you anything new by talking you through each of the necessary changes, so I'll mention the important changes and then post your corrected code:

    paintComponent(() should begin with a call to the super's paintComponent() method

    NEVER, NEVER, NEVER call repaint from the paintComponent() method. Doing so creates an infinite loop and indicates you don't understand Swing's painting mechanism. You can learn more about it in Oracle's Custom Painting lesson.

    Use the setColor() method between dialog boxes to change the light's color. (Should be named setLightColor().)

    You might want to move the first dialog to after the setVisible() statement and then alternate change color / new dialog, but that's up to you.

    Here's the working code:
    //Traffic Light viewer
    //Import JComponent Graphics, Graphic2D, Color
    import java.awt.Color;
    import java.awt.Graphics;
    import java.awt.Graphics2D;
    import java.awt.Rectangle;
    import java.awt.geom.Ellipse2D;
     
    import javax.swing.JComponent;
    import javax.swing.JFrame;
    import javax.swing.JOptionPane;
     
     
    public class TestClass
    {
        public static void main(String[] args)
        {
            JFrame LightVisible = new JFrame();
            LightVisible.setSize(400,400);
            LightVisible.setTitle("Traffic Lights");
            LightVisible.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            TrafficLight trafficViewerOne = new TrafficLight();
     
            JOptionPane.showMessageDialog(null,"Ready!");
     
            LightVisible.add(trafficViewerOne);
     
            LightVisible.setVisible(true);
     
     
            JOptionPane.showMessageDialog(null,"Set!");
     
            trafficViewerOne.setColor( Color.YELLOW );
     
            JOptionPane.showMessageDialog(null,"Go!");
     
            trafficViewerOne.setColor( Color.GREEN );
        }
     
    }
     
    class TrafficLight extends JComponent
    {
        private Color lightColor;
     
        public TrafficLight()
        {
            // set initial color to green
            lightColor = Color.RED;
        }
     
        public void paintComponent(Graphics g)
        {
            // always begin the paintComponent() method with:
            super.paintComponent( g );
     
            //convert g to graphics 2d and use to draw ellipse for circle.
            //set color to lightColor
            Graphics2D g2 = (Graphics2D) g;
            Rectangle box = new Rectangle(0,0,300,400);
            g2.setColor(Color.WHITE);
            g2.fill(box);    
     
            Ellipse2D.Double lightRing = new Ellipse2D.Double(35,75,200,200);
            g2.setColor( lightColor );
            g2.draw(lightRing);
            g2.fill(lightRing);
        }
     
        public void setColor(Color newLightColor)
        {
            lightColor = newLightColor;
            repaint();
        }
     
    }

  3. The Following User Says Thank You to GregBrannon For This Useful Post:

    Edmacelroy (September 29th, 2013)

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