Sealed classes in Java let developers limit the creation and use of subclasses and preserve the class hierarchy. Here is how sealed classes in Java work.

Abstract classes and interfaces in Java serve fundamentally different purposes. Learn the differences between these Java language elements and how to use them in your programs.

To implement the Java virtual machine correctly, you need only be able to read the class file format and correctly perform the operations specified therein.

And it uses a function called Ahead-of-Time (AOT) compilation to compile Java classes and methods in advance, to shorten the startup time.