Class Loaders
#runtime #jvm
Every Class object contains a reference to the ClassLoader that defined it. In addition to loading classes, a class loader is also responsible for locating resources (e.g. properties, images, .class files). When a class loader finds a class by URL, it needs to link it.
Linking is the process of taking a binary form of a class or interface type and combining it into the run-time state of the JVM, so that it can be executed.
The Java SE Platform API historically specified two class loaders:
•
Bootstrap class loader — the logical classloader that has responsibility for loading the classes (and resources) that are found in the boot-classpath - typically the core Java platform classes (
/jre/lib). Usually it's implemented in native code.
• System class loader — the default delegation parent for new class loaders and, typically, the class loader used to load and start the application. This one loads your application's classes and libraries's classes from the classpath.
