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.

For new Java programmers, the JOptionPane class is a great visual and user-friendly introduction to user input and Swing-based programming. Here's how to get started.

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.