Friday 14 September 2012

Java Training: -What do you mean by Bootstrap, Extension and System Class loader?

There three types of class loaders:-
  • Bootstrap Class loader also called as primordial class loader.
  • Extension Class loader.
  • System Class loader.
Let’s now try to get the fundamentals of these class loaders.

Bootstrap Class loader

Bootstrap class loader loads those classes those which are essential for JVM to function properly. Bootstrap class loader is responsible for loading all core java classes for instance java.lang.*,* etc. Bootstrap class loader finds these necessary classes from “jdk/jre/lib/rt.jar”. Bootstrap class loader cannot be instantiated from JAVA code and is implemented natively inside JVM.

Extension Class loader

The extension class loader also termed as the standard extensions class loader is a child of the bootstrap class loader. Its primary responsibility is to load classes from the extension directories, normally located the “jre/lib/ext” directory. This provides the ability to simply drop in new extensions, such as various security extensions, without requiring modification to the user's class path.

System Class loader

The system class loader also termed application class loader is the class loader responsible for loading code from the path specified by the CLASSPATH environment variable. It is also used to load an application’s entry point class that is the "static void main ()" method in a class.

See the following video on overview and working of Servlets in Java: -

Click to get Java Training


Get more Java Training from author’s blog


  1. I really appreciate this great post that you have provided us. I guarantee this will benefit most people and myself. thank you very much!
    hancom office editor
    how to take a screenshot on samsung tablet
    how many cm in a meter
    roblox error code 524

  2. Nice post, glad to visit here. If your youtube is blocked in your location, but you want to find an easy way to access it then, you should simply go through Node unblocker. Here we discussed how to unblock youtube.

  3. Thank you for giving us informative points through this blog. If you are an android user searching for how to Unlock Snapchat++ mod
    on your device? If yes, Then I suggest an article about the OGzilla. Here you get all the premium features for free. It's so helpful to work. For more points check an article.