Hi folks, I have to answer the following question:

"Write an applet which contains a panel whose background colour varies as the elevators of three Scrollbar objects are varied. Each Scrollbar object affects one colour constituent."

I think I'm pretty close, but I can't figure out why only one of the scrollbars changes colour. They should change red, green, and blue respectively.
I'd be really grateful for any help on this one. Thanks!

/*applet which demonstrates the use of a canvas*/
import java.awt.*;


public class u extends java.applet.Applet
{
Canvas can;
Scrollbar s;
Color bg;
int b;
int g;
int r;


public void init()
{
setLayout(new GridLayout(1, 2, 10, 10));


bg = new Color(0, 0, 255);
can = new Canvas();
s = new Scrollbar(Scrollbar.VERTICAL, 0, 0, 0, 255);
can.setBackground(bg);
add(can);
add(s);
bg = new Color(0, 255, 0);
s = new Scrollbar(Scrollbar.VERTICAL, 0, 0, 0, 255);
can.setBackground(bg);
add(s);
bg = new Color(255, 0, 0);
s = new Scrollbar(Scrollbar.VERTICAL, 0, 0, 0, 255);
can.setBackground(bg);
add(s);
}


public boolean handleEvent(Event evt)
{
if (evt.target instanceof Scrollbar)
{
r = s.getValue();
g = s.getValue();
b = s.getValue();
bg = new Color(r, g, b);
can.setBackground(bg);
can.repaint();
}
return true;
}
}

Edited 3 Years Ago by pyTony: fixed formating

This is your problem, you only have one instance of a scrollbar. You'll need to have 3 of them, and fix the handleevent so that it will check to see which one was fired.

hi bigriggers,

as server crash had mentioned u have only one instance.

I have attached a running version. Hope this is what you are looking for:
I have made this into a awt standalone application

import java.awt.*;
import java.awt.event.*;

public class u extends Frame
{
Canvas can;
Scrollbar s1,s2,s3;
Color bg;
int b;
int g;
int r;

    public u()
    {
    setLayout(new GridLayout(1, 2, 10, 10));
    bg = new Color(0, 0, 255);
    can = new Canvas();
    s1 = new Scrollbar(Scrollbar.VERTICAL, 0, 0, 0, 255);
    can.setBackground(bg);
    add(can);
    add(s1);

    bg = new Color(0, 255, 0);
    s2 = new Scrollbar(Scrollbar.VERTICAL, 0, 0, 0, 255);
    can.setBackground(bg);
    add(s2);

    bg = new Color(255, 0, 0);
    s3 = new Scrollbar(Scrollbar.VERTICAL, 0, 0, 0, 255);
    can.setBackground(bg);
    add(s3);


    setSize(300,300);
    setVisible(true);
}

    public boolean handleEvent(Event evt)
    {
        if (evt.target instanceof Scrollbar)
        {
            r = s1.getValue();
            g = s2.getValue();
            b = s3.getValue();
            bg = new Color(r, g, b);
            can.setBackground(bg);
            can.repaint();
        }
    return true;
    }

    public static void main(String args[])
    {
        new u();
    }
}

Edited 3 Years Ago by pyTony: fixed formating

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