GregorianCalendar to read the time of day & then drawing hands on clock

Question

I am currently working on a program that displays an analog clock. The program uses an object of type GregorianCalendar to read the hours, mins, and secs, and then I need to draw hands on a clock accordingly. I can read the time using GregorianCalendar, but once i have the time, I am unsure how to draw the hands that coordinate with the time. i already have the clock face drawn, and I am implementing the Icon interface's paintIcon(....) method for that. Any suggestions would be greatly appreciated.
Thanks.

Answer 1

thats what i was trying to do but something isnt working out right. I've
attached my code.
//splits the clock into sections for seconds
double radians_per_second = ((2 * Math.PI)/3600);Are you sure that's correct...? It should have the same amount of sections as the minute hand, so I think this is incorrect... No biggy, though...
double x_hour = ((Math.cos(hours))*sizeHourHand);
double y_hour = ((Math.sin(hours))*sizeHourHand);
double x_minute = (((Math.cos(minutes))*sizeMinuteHand)); //to correct for rotation
double y_minute = (((Math.sin(minutes))*sizeMinuteHand));
double x_second = (((Math.cos(seconds))*sizeSecondHand));
double y_second = (((Math.sin(seconds))*sizeSecondHand));Here, you're calculating the size of one of the sides of the triangle, not the point itself!! Thus...
//creating the face of the clock
Ellipse2D.Double clockFace= new Ellipse2D.Double(0, 0, clockHeight, clockWidth);
Point2D.Double hourHandPoint= new Point2D.Double(x_hour, y_hour);
Point2D.Double minuteHandPoint= new Point2D.Double(x_minute, y_minute);
Point2D.Double secondHandPoint= new Point2D.Double(x_second, y_second);
Point2D.Double center= new Point2D.Double(radius, radius);
Line2D.Double hourHand= new Line2D.Double(center, hourHandPoint);
Line2D.Double minuteHand= new Line2D.Double(center, minuteHandPoint);
Line2D.Double secondHand= new Line2D.Double(center, secondHandPoint);
What you're drawing here is incorrect...
//drawing the clock
g2.setColor(Color.WHITE);
g2.draw(clockFace);
g2.fill(clockFace);
g2.setColor(Color.BLACK);
g2.draw(hourHand);
g2.draw(minuteHand);
g2.draw(secondHand);I'll explain using degrees instead of radians:
The angle for the hands' apperture should give you something between 0 and 360 degrees (non-inclusive), depending on the value, you should determine wether the hand will sit on one of quadrants 1 through 4...
Substract whatever amount of degrees to reduce the angle to anything from 0 to 90 (non-inclusive), otherwise those calculations I suggested won't work!! We need an angle that fits with a right triangle here...
From there, calculate the size of the triangle's sides (as suggested previously) and add or substract to the center point, the X and Y coords of the newly calculated sides, depending on the quadrant....
This should give you the second point to draw the line with...
I know it's long and boring, but I told you so, didn't I...?
There must be an easier way...