Download: java1.zip.
Test2.java
// Test2.java import java.awt.Graphics; import java.awt.Color; import javax.swing.JPanel; import javax.swing.JFrame; import java.util.ArrayList; public class Test2 extends JPanel { ArrayList<Ball> balls = new ArrayList<Ball>(); Test2() { balls.add(new Ball(50,50,Color.RED)); balls.add(new Ball(100,120,Color.BLUE)); balls.add(new Ball(160,50,Color.YELLOW)); System.out.println("Balls:"); for (Ball b: balls) System.out.println(b); } public void paintComponent(Graphics g) { super.paintComponent( g ); for (Ball b: balls) b.draw(g); } public static void main(String args[] ) { Test2 panel = new Test2(); JFrame application = new JFrame("Test2"); application.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); application.add(panel); application.setSize(200,200); application.setVisible(true); } }
Ball.java
import java.awt.*; public class Ball { double px, py; int radius; double mass; Color color; Ball() { color = new Color(255,0,0); set_position(50,50); set_radius(17); } Ball(double px, double py, Color color) { this.color = color; set_position(px,py); set_radius(17); } void set_position(double px, double py) { this.px = px; this.py = py; } void set_radius(int r) { radius = r; mass = r*r; } public String toString() { String str = "("+px+", "+py+") " + color; return str; } public void draw(Graphics g) { g.setColor(color); g.fillOval((int)(px-radius), (int) (py-radius), (int)2*radius, (int)2*radius); } }
Maintained by John Loomis, updated Thu Jun 02 16:50:01 2016