Arrays in Java are variables that contain multiple values. These let you store things like lists of high scores or phone numbers and can also be organized, counted, and manipulated in other ways.

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.

Method and variable handles vs. Java reflection. To truly understand MethodHandles and VarHandles—what they do and why they are useful—it’s helpful to know a few things about reflection in Java.