Why does sun.misc.Launcher$AppClassLoader.loadClass appear in the stack

Question

I have instrumented JDK and application. Entry and exit points are recorded for call graph construction.

The call graph looks like

sun.misc.Launcher$AppClassLoader.loadClass->com.example.Main.main
->sun.misc.Launcher$AppClassLoader.loadClass->com.example.Foo.foo

Source code

public class Main{
public static void main(String[] args){
  Foo.foo()
}
}

public class Foo{
  public static void foo(){};
}

This must be how classloader works but I don't see anything shows in bytecode that indicate the call site "sun.misc.Launcher$AppClassLoader.loadClass". So, how does classloader work internally?

Answer 1

Classes are loaded lazily.

You can see this by writing code to print to the console within static initialisers.

The first time a class reference is used by any code loaded by a specific class loader, the JVM request the Class from the loader in the current thread. If the parent class loader hasn't loaded a class of the fully qualified name, then the current class loader will define it (or throw an exception).

In the early days applets would make a network connection for each class file.