Graphics2D / Swing Density Issues

Question

Hi all,
I'm relativley new to coding in java and first time posting in the forums so please be gentle.... I am writing a program that will work in unison w/ a graph drawing algorithm that was written in C. Java does the drawing and my C code does the calculations. The problem seems to be that my GUI when dealing with very large dense graphs starts to lag like crazy (long delay when buttons / menus are clicked). At first i thought it was constantly repainting the graph which would cause a lag but that does not seem to be the case. Can the graphics2d library just not handle something like a dense graph (like over 100,000 lines drawn to represent the edges)? Or have i fouled up my code. If you'd like, here is a link to it, it's not terribly complex (like i said, i'm new):
http://www.rpi.edu/~boceke/Drawer.java
Perhaps i'm going about drawing huge graphs in an inefficent way, like using a library i shouldn't be, and if that's the case please let me know what library i should be using to draw really dense graphs.
Thanks much in advance,
-Eli

Answer 1

Just running this code, it takes about 1.5 - 2 seconds to draw 100,000 lines from random numbers. There's 2 versions, one which generates random numbers each time thru the loop, one that generates them before painting. Either case, the results are the same, so that tells me that painting that much is really slow.
My only thought is that maybe somehow you can lessen what actually needs to be drawn. How you can do that, I don't know... I suppose it depends on the data.
import java.awt.*;
import javax.swing.*;
import java.util.*;
public class Draw extends JPanel {
     public static void main(String[] args) {
          JFrame f = new JFrame();
          f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          f.getContentPane().add(new Draw());
          f.pack();
          f.setSize(500, 500);
          f.setVisible(true);
     private Random r = new Random();
     public void paintComponent(Graphics g) {
          System.out.println("start " + System.currentTimeMillis());
          g.setColor(Color.black);
          g.fillRect(0, 0, getSize().width, getSize().height);
          g.setColor(Color.yellow);
          int size = 100000;
          int x1, y1, x2, y2 = 0;
          for(int j = 0; j < size; j++) {
               x1 = r.nextInt(400) + 50;
               y1 = r.nextInt(400) + 50;
               x2 = r.nextInt(400) + 50;
               y2 = r.nextInt(400) + 50;
               g.drawLine(x1, y1, x2, y2);
          System.out.println("end " + System.currentTimeMillis());
import java.awt.*;
import javax.swing.*;
import java.util.*;
public class Draw extends JPanel {
     public static void main(String[] args) {
          JFrame f = new JFrame();
          f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          f.getContentPane().add(new Draw());
          f.pack();
          f.setSize(500, 500);
          f.setVisible(true);
     private static int size = 100000;
     private static int[] X1 = new int[size];
     private static int[] Y1 = new int[size];
     private static int[] X2 = new int[size];
     private static int[] Y2 = new int[size];
     private static Random r = new Random();
     static {
          for(int i = 0; i < size; i++) {
               X1[i] = r.nextInt(400) + 50;
               Y1[i] = r.nextInt(400) + 50;
               X2[i] = r.nextInt(400) + 50;
               Y2[i] = r.nextInt(400) + 50;
     public void paintComponent(Graphics g) {
          System.out.println("start " + System.currentTimeMillis());
          g.setColor(Color.black);
          g.fillRect(0, 0, getSize().width, getSize().height);
          g.setColor(Color.yellow);
          for(int j = 0; j < size; j++) {
               g.drawLine(X1[j], Y1[j], X2[j], Y2[j]);
          System.out.println("end " + System.currentTimeMillis());
}