class-loader.

　　　　　　　　　　the jdk hierarchical relationship of class-loader

　　　　　　

----Module Class Loading and Bootstrapping----

bootstrap loader:

　　 *loads primordial classes and core module system classes.

Base module loader

　　*loads non-core module system classes and all other classes in the base module.

ref:

Project Jigsaw: Module Class Loading and Bootstrapping

----How Classes are Found----

　　how the 'java(java launcher)' finds classes:

　　the vm searches for and loads classes in the order of:

　　a,bootstrap classes,which compriss the java platform,including the classes in the rt.jar and other important .jar files.

　　b,extension classes,which use the java extension mechanism,bundled as .jar files in the “lib/ext” extension directory.

　　c,user(defined) classes,which were definded by developers and third parties that does not take advantage of the extension mechanism(identify these classes using the -classpath option).

　　more info for How Classes are Found