Question

I have notice that you can specify <package /> properties in JNLP like described here:
http://lopica.sourceforge.net/ref.html#package

What are the advantages of explicitelly defining them over letting the applet classloader do the job?

Answer 1

The JSR-56 spec explains the reasons:

http://jcp.org/aboutJava/communityprocess/mrel/jsr056/index5.html

4.5 Package Element

…

The package element only makes sense to use with lazily-downloaded
resources, since all other resources will already be available to the
JVM. Thus, it will already know what packages are implemented in those
JAR files. However, it can direct the JNLP Client to download the
right lazy JAR resources, instead of having to download each
individual resource one at a time to check.