On 11/15/2013 12:37 PM, Ioi Lam wrote:
From sun.misc.Launcher$ExtClassLoader:
private static URL[] getExtURLs(File[] dirs) throws IOException {
Vector<URL> urls = new Vector<URL>();
for (int i = 0; i < dirs.length; i++) {
String[] files = dirs[i].list();
if (files != null) {
for (int j = 0; j < files.length; j++) {
if (!files[j].equals("meta-index")) {
File f = new File(dirs[i], files[j]);
urls.add(getFileURL(f));
}
}
}
}
URL[] ua = new URL[urls.size()];
urls.copyInto(ua);
return ua;
}
the search order is completely depending on the order of files
returned by File.list(), whose Javadoc explictly says the order is not
defined:
http://docs.oracle.com/javase/6/docs/api/java/io/File.html#list()
"There is no guarantee that the name strings in the
resulting array will appear in any specific order;
they are not, in particular, guaranteed to appear
in alphabetical order."
So, what happens when the same class file exists in two JAR files in
lib/ext?
AFAIK The extension mechanism [1] doesn't specify the ordering of files
searched in the directories listed in
java.ext.dirs system property.
If there are two JAR files in lib/ext containing the class file of the
same name, the behavior is undefined.
Mandy
[1]
http://docs.oracle.com/javase/7/docs/technotes/guides/extensions/spec.html#installed
