> 1) jdk1.1.5
> 2) classes_net
> 3) solaris 2.6 sparc
> 4) bug
> When loading many images at a time - NullPointerException in
guessContentTypeFro
> 5) (how to reproduce)
> /* $Header: ImageBugDemo.java,v 1.1 97/12/17 12:01:14 dsb Locked $ */
>
> /*
> *bcpyrght
> *****************************************************************************
> * Copyright 1993 - 1998 VERITAS Software Corporation, All Rights Reserved *
> *****************************************************************************
> *ecpyrght
> */
>
> import java.awt.*;
> import java.net.*;
>
> public class ImageBugDemo extends Component{
>
> MediaTracker tracker;
>
> public ImageBugDemo(int nImages) {
> tracker = new MediaTracker(this);
> Image Icon;
>
> for (int i = 1; i <= nImages; i++) {
> URL url = getImageURL(i);
> System.out.println("Creating Image for "+url);
> Icon = Toolkit.getDefaultToolkit().getImage(url);
> tracker.addImage(Icon,i);
> try {
> //Thread.sleep(100);
> tracker.waitForID(i);
> } catch (InterruptedException e) {
> System.out.println("interupted waiting for Icon");
> }
> }
> try {
> Thread.sleep(10000);
> } catch (InterruptedException e) {
> System.out.println("interupted sleeping after load");
> }
> }
>
> public static void main(String args[]) {
> int nImages = 50;
>
> if (args.length < 1) {
> System.out.println("Usage: java ImageBugDemo <#images>");
> System.exit(1);
> }
> try {
> nImages = Integer.parseInt(args[0]);
> } catch (Exception e) { }
>
> ImageBugDemo bug = new ImageBugDemo(nImages);
> System.out.println("Yea - we made it!");
> System.exit(0);
> }
>
> private URL getImageURL(int i) {
> return this.getClass().getResource("bug_images/i"+i+".gif");
> }
> }
> -------------------------------------------------
> create a bug_images subdirectory with lots of
> images named i0.gif, i1.gif... I used the
> following gif and just created 100 identical
> files:
> ls bug_images
> i0.gif i2.gif i31.gif i43.gif i55.gif i67.gif i79.gif i90.gif
> i1.gif i20.gif i32.gif i44.gif i56.gif i68.gif i8.gif i91.gif
> i10.gif i21.gif i33.gif i45.gif i57.gif i69.gif i80.gif i92.gif
> i100.gif i22.gif i34.gif i46.gif i58.gif i7.gif i81.gif i93.gif
> i11.gif i23.gif i35.gif i47.gif i59.gif i70.gif i82.gif i94.gif
> i12.gif i24.gif i36.gif i48.gif i6.gif i71.gif i83.gif i95.gif
> i13.gif i25.gif i37.gif i49.gif i60.gif i72.gif i84.gif i96.gif
> i14.gif i26.gif i38.gif i5.gif i61.gif i73.gif i85.gif i97.gif
> i15.gif i27.gif i39.gif i50.gif i62.gif i74.gif i86.gif i98.gif
> i16.gif i28.gif i4.gif i51.gif i63.gif i75.gif i87.gif i99.gif
> i17.gif i29.gif i40.gif i52.gif i64.gif i76.gif i88.gif
> i18.gif i3.gif i41.gif i53.gif i65.gif i77.gif i89.gif
> i19.gif i30.gif i42.gif i54.gif i66.gif i78.gif i9.gif
>
> Here is that image uuencoded:
> begin 644 bug_images/i0.gif
> M1TE&.#=A$ 0 *$ ,# P(" @/___RP $ 0 "/82"J0J]CXP
> M<,G9LLZB&S"$8MATF#: Y/6-8^F=*4BSDRO"9ZW.9HOSQ5 9X>06I)0V,Q4E
> *@$'BGI&-M0 .]AT
>
> end
>
> -------------------------------------------------
> run with: java ImageBugDemo 100
> results vary with size of image, type of machine,
> number of images, etc. Solaris 2.6 and 2.5.1 behave
> very similarly (one crashes after 24 images, the
> other after 26 images, but these machines are
> also different chips: SPARCcenter-2000 and Ultra-2)
>
> -------------------------------------------------
> **** This is the error you should see:
> Uncaught error fetching image:
> java.lang.NullPointerException
> at
java.net.URLConnection.guessContentTypeFromStream(URLConnection.java)
> at sun.net.www.URLConnection.getContentType(URLConnection.java:126)
> at sun.awt.image.URLImageSource.getDecoder(URLImageSource.java:98)
> at
sun.awt.image.InputStreamImageSource.doFetch(InputStreamImageSource.java:259)
> at sun.awt.image.ImageFetcher.fetchloop(ImageFetcher.java:151)
> at sun.awt.image.ImageFetcher.run(ImageFetcher.java:127)
> **** then, the whole application hangs (and if you
> **** are doing this within hotjava, hotjava hangs, too)
> -------------------------------------------------
>
> 6) (workaround)
> Put a Thread.sleep(100) in-between each image load
> (doesn't work in all situations. Longer pauses
> work better, but when running under hotjava, the
> pause has to be pretty substantial)