Databases
StackOverflow2013
Postsdbo
POJava Applets- creating a interactive traffic light without using 'canvas'?
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POJava Applets- creating a interactive traffic light without using 'canvas'?
    primarykey
    data
    text
    <p>To make it short I want to design a java applet that shows a traffic light with three adjacent buttons. One that says red light, one that says amber light and one for green.</p> <hr> <p>My problem is: is that I don't know how to link each button with the right oval. All of the ovals belong to the same Graphics variable g. If I change the color all three would be changed. </p> <p>There is a superclass called canvas that helps separate each object in its own entity from my knowledge but I know there is an easier way. </p> <p>How can I do this?</p> <pre><code>import java.awt.*; import java.awt.event.*; import java.applet.*; import java.applet.Applet; public class Traffic extends Applet implements ActionListener { int colourNum; //global variable which is responible for changing the light Button bttn1 = new Button ("Stop Traffic"); Button bttn2 = new Button ("Caution"); Button bttn3 = new Button ("Proceed"); public void init () { setBackground (Color.lightGray); bttn1.addActionListener (this); // stop light bttn2.addActionListener (this); // yellow light bttn3.addActionListener (this); // green light add (bttn1); add (bttn2); add (bttn3); } public void paint (Graphics g) // responsible for graphics "within" the window { g.setColor (Color.black); switch (colourNum) { case 1: g.setColor (Color.red); break; } g.fillOval (30, 40, 20, 20); // red light g.fillOval (30, 70, 20, 20); // yello light g.fillOval (30, 100, 20, 20); // green light } public void actionPerformed (ActionEvent evt) { if (evt.getSource () == bttn1) colourNum = 1; else if (evt.getSource () == bttn2) colourNum = 2; else colourNum = 3; repaint (); } } </code></pre>
    singulars
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. This table or related slice is empty.
    1. USFryon Alexandra
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. COYou should avoid overriding paint on top level containers like Appet. You should also be calling super.paint to honour the paint chain
      singulars
      1. POJava Applets- creating a interactive traffic light without using 'canvas'?
      1. USMadProgrammer
    2. COIt would be better to create new `Canvas`-based components to individually handle the painting of the traffic signals.
      singulars
      1. POJava Applets- creating a interactive traffic light without using 'canvas'?
      1. USReimeus
    3. COThe best strategy might be to have a `TrafficLights` class that knows how to draw itself and its state (e.g. red, green, blinking yellow. When it comes time to draw it. Call `TrafficLights.draw(Graphics)` from within paint in order to paint the current state.
      singulars
      1. POJava Applets- creating a interactive traffic light without using 'canvas'?
      1. USAndrew Thompson
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload