i want create method creates 5 balls on panel. can please me around using paint component method or creating own draw method. can see bellow, have paint component method loop loop 5 , create ball in random location, unfortunately 1 ball being created.
import java.awt.*; import java.util.random; import javax.swing.*; public class allballs extends jpanel { int number_ball=5; int x,y; graphics g; allballs(){ random r = new random(); x=r.nextint(320); y=r.nextint(550); } public static jframe frame; public static void main(string[] args) { allballs a= new allballs(); frame= new jframe("bouncing balls"); frame.setsize(400,600); frame.setdefaultcloseoperation(frame.exit_on_close); frame.setvisible(true); frame.add(a); } @override protected void paintcomponent(graphics g) { super.paintcomponent(g); for(int i=0;i<number_ball;i++){ g.filloval(x, y, 30, 30); } repaint(); } } in paintcomponent method, created loop in wanted 5 ball created, 1 being created on screen.
recommendations per comments:
- get rid of graphics g variable hurt you.
- consider creating non-gui ball class, 1 not extend swing component , has own paint(graphics) method.
- if need 5 balls, create array of ball objects in allballs class.
- in paintcomponent, iterate through balls painting each 1 calling paint or draw method (whatever name method).
- if need move balls, in swing timer moves balls , calls repaint(). whatever do, not call
repaint()within paintcomponent method results in bastardization of method, , results in uncontrolled animation. method should painting , painting , not animation or code logic. use swing timer instead. - also don't randomize ball locations within paintcomponent, recommendation made in now-deleted answer. again, paintcomponent should painting , painting , not program logic or change state of class. randomization should within swing timer or game loop.
for example:
import java.awt.color; import java.awt.dimension; import java.awt.graphics; import java.awt.graphics2d; import java.awt.renderinghints; import java.awt.event.actionevent; import java.awt.event.actionlistener; import java.util.arraylist; import java.util.list; import java.util.random; import javax.swing.*; @suppresswarnings({"serial", "unused"}) public class ballimages extends jpanel { private static final int pref_w = 800; private static final int pref_h = pref_w; private static final int ball_count = 15; private static final color[] colors = { color.red, color.black, color.blue, color.cyan, color.green, color.orange, color.pink, color.white, color.magenta, color.yellow }; private static final int min_speed = 2; private static final int max_speed = 10; private static final int min_width = 10; private static final int max_width = 30; private static final int timer_delay = 15; private list<ball> balls = new arraylist<>(); private random random = new random(); public ballimages() { (int = 0; < ball_count; i++) { int ballwidth = min_width + random.nextint(max_width - min_width); color ballcolor = colors[random.nextint(colors.length)]; int ballx = ballwidth / 2 + random.nextint(pref_w - ballwidth / 2); int bally = ballwidth / 2 + random.nextint(pref_h - ballwidth / 2); double direction = 2 * math.pi * math.random(); double speed = min_speed + random.nextint(max_speed - min_speed); ball ball = new ball(ballwidth, ballcolor, ballx, bally, direction, speed); balls.add(ball); } new timer(timer_delay, new timerlistener()).start(); } @override protected void paintcomponent(graphics g) { super.paintcomponent(g); graphics2d g2 = (graphics2d) g; g2.setrenderinghint(renderinghints.key_antialiasing, renderinghints.value_antialias_on); (ball ball : balls) { ball.draw(g2); } } @override // set component's size in safe way public dimension getpreferredsize() { if (ispreferredsizeset()) { return super.getpreferredsize(); } return new dimension(pref_w, pref_h); } private class timerlistener implements actionlistener { @override public void actionperformed(actionevent e) { if (!ballimages.this.isdisplayable()) { ((timer) e.getsource()).stop(); } (ball ball : balls) { ball.move(pref_w, pref_h); } repaint(); } } private class ball { private int width; private color color; private double x; private double y; private double direction; private double speed; private double deltax; private double deltay; public ball(int width, color color, int x, int y, double direction, double speed) { this.width = width; this.color = color; this.x = x; this.y = y; this.direction = direction; this.speed = speed; deltax = speed * math.cos(direction); deltay = speed * math.sin(direction); } public int getwidth() { return width; } public color getcolor() { return color; } public double getx() { return x; } public double gety() { return y; } public double getdirection() { return direction; } public double getspeed() { return speed; } public void draw(graphics2d g2) { g2.setcolor(color); int x2 = (int) (x - width / 2); int y2 = (int) (y - width / 2); g2.filloval(x2, y2, width, width); } public void move(int containerwidth, int containerheight) { double newx = x + deltax; double newy = y + deltay; if (newx - width / 2 < 0) { deltax = math.abs(deltax); newx = x + deltax; } if (newy - width / 2 < 0) { deltay = math.abs(deltay); newy = y + deltay; } if (newx + width / 2 > containerwidth) { deltax = -math.abs(deltax); newx = x + deltax; } if (newy + width / 2 > containerheight) { deltay = -math.abs(deltay); newy = y + deltay; } x = newx; y = newy; } } private static void createandshowgui() { ballimages mainpanel = new ballimages(); jframe frame = new jframe("ballimages"); frame.setdefaultcloseoperation(jframe.dispose_on_close); frame.getcontentpane().add(mainpanel); frame.setresizable(false); frame.pack(); frame.setlocationrelativeto(null); frame.setvisible(true); } public static void main(string[] args) { swingutilities.invokelater(new runnable() { public void run() { createandshowgui(); } }); } } 
Comments
Post a Comment