Applets

**santiagomez** · July 29th, 2010, 07:02 AM

Hey, I've been set the following question as part of my programming class:
Write an applet that draws a series of concentric circles, alternating between red and blue in colour, the largest of which fits exactly within the applet drawing area. Use loops as appropriate. The number of circles should be specified as a parameter to the applet; if unspecified or invalid, it should default to 2.
You may need to use the following methods of the Graphics class: setColor(Color c): set the drawing colour drawOval(x,y,xdia,ydia): draws an oval

I'm able to draw the concentric circles with no problem but the changing of the colour for every second one is the part that is causing me problems....any help welcome
Santiagomez

**Norm** · July 29th, 2010, 07:18 AM

changing of the colour for every second one is the part that is causing me problems

You need some logic to select a color for every circle. Many ways to do this.
Have a method that returns a color and call that for the next color to use.
Now use some brain power and think how the method can return a different color every time it is called.
How about an array of colors that it steps thru with an index.

**Asido** · July 31st, 2010, 04:05 PM

Here is one way. Changes the green color from the RGB. This way it goes from nearly white to violet and vice versa. Just the timer is missing which would repaint the oval after particular delay.

RGBgreen = 2;
direction = 1;
---------------------------------------------------
RGBgreen += direction;
if(RGBgreen <= 1 || RGBgreen >= 254)
            direction = -direction;
Color theColor = new Color(192, RGBgreen, 192);
g.setColor(theColor);
g.drawOval(x, y, width, height);

EDIT: sorry if helped you too much. I gave you the answer.

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