What loads the java system classloader?

Question

We know that we can override the System classloader with:

java -Djava.system.class.loader=com.test.MyClassLoader xxx

Then, since com.test.MyClassLoader itself is a class, by whom is it loaded?

How do we get the class file of this "meta" classloader?

Answer 1

Bootstrap classloader is the parent of all classloaders and loads the standard JDK classes in lib directory of JRE (rt.jar and i18n.jar). All the java.* classes are loaded by this classloader.

Extensions Classloader is the immediate child of Bootstrap classloader. This classloader loads the classes in libext directory of the JRE.

System-Classpath classloader is the immediate child of Extensions classloader. It loads the classes and jars specified by the CLASSPATH environment variable

You could try to inject your custom class loader by means of the "java.system.class.loader" property (see ClassLoader#getSystemClassLoader).

Default System class loader is parent for MyClassLoader instances,