I'm trying to animate a square moving in a circle within the canvas. I have gotten a square to move back and forth within the frame but I'm having some difficulty laying out the circular motion. I created a variable theta which changes of a swing timer, therefore altering the overall position of the shape. However when I run it nothing happens. I'm also not sure if I should be using doubles or ints since the drawRectangle command only accepts ints but the math is complex enough to require double values. Here's what I have so far:
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
public class Circle extends JPanel implements ActionListener{
Timer timer = new Timer(5, this);
Double theta= new Double(0);
Double x = new Double(200+(50*(Math.cos(theta))));
Double y = new Double(200+(50*(Math.sin(theta))));
Double change = new Double(0.1);
int xp = x.intValue();
int yp = y.intValue();
public void paintComponent(Graphics g){
super.paintComponent(g);
g.setColor(Color.BLUE);
g.fillRect(xp, yp, 50, 50);
timer.start();
}
public void actionPerformed(ActionEvent e) {
theta=theta+change;
repaint();
}
public static void main(String[] args){
Circle a = new Circle();
JFrame frame = new JFrame("Circleg");
frame.setSize(600, 600);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(a);
}
}
theta=theta+change;
repaint();
You don't change the xp, yp values. They will not magically update themselves just because the theta value changes.
Move the code calculating the x/y location right into the paintComponent() method.
Double x = new Double(200+(50*(Math.cos(theta))));
Double y = new Double(200+(50*(Math.sin(theta))));
int xp = x.intValue();
int yp = y.intValue();
g.fillRect(xp, yp, 50, 50);
Also,
timer.start();
Do NOT start the Timer in the painting method. Painting methods are for painting only.
The Timer should be started in the constructor of your class.
Collected from the Internet
Please contact [email protected] to delete if infringement.
Comments