Java Classloaders by Simon Maple

Class loaders are at the core of the Java language. Java EE containers, OSGi, NetBeans modules, Tapestry 5, Grails and many others use class loaders heavily. Yet when something goes wrong, would you know how to solve it?
In this session we'll take a tour of the Java class loading mechanism, both from JVM and developer point of view. We will look at typical problems that you get with class loading and how to solve them. ClassNoDefError, IncompatibleClassChangeError, LinkageError and many others are symptoms of specific things going wrong that you can usually find and fix. For each problem we'll go through a hands on demo with a corresponding solution.
We'll also take a look at how and why class loaders leak and how can you remedy that.

Simon Maple is a Developer Advocate at ZeroTurnaround, a Java Champion since 2014, JavaOne Rockstar speaker in 2014, Virtual JUG founder and organiser, London Java Community co-leader and RebelLabs author. He is an experienced speaker, having presented at JavaOne, JavaZone, Jfokus, DevoxxUK, DevoxxFR, JavaZone, JMaghreb and many more including many JUG tours. His passion is around user groups and communities. When not traveling, Simon enjoys spending quality time with his family, cooking and eating great food.

[Satenc]

I still have a question that I can only illustrate through the next example: Suppos we have ClassLoader1 which extends from ClassLoader, we also have ClassLoader2 which also extends from ClassLoader, then, at application bootstrap ClassLoader1 requests a Zip File which contains many classes and then loads them all to the JVM, then at some point ClassLoader2 also gets a Zip file with other classes, and it is going to load them too to the jvm, but some of them depend on classes that where loaded previously by ClassLoader1 (some of them might extend or use stuff from those classes), my question is, will ClassLoader2 be capable of loading the classes that depend on classes loaded by ClassLoader1 on bootstrap? (my guess is yes because they are on the jvm)

[sathishrtskumar]

Well explained, got better understanding... Congrats

[makarandb]

Great video. Can you share the GitHub link for the code used in the video?