Arrays in Java are variables that contain multiple ... Variables also act differently depending on how they interact with their class (instance variables vs static variables).

Can have instance mutable fields, parameters, or local variables. Only functional interfaces can use the lambda feature in Java. Abstract classes with only one abstract method cannot use lambdas.

The static keyword often confuses junior Java developers. A static variable is one that is not attached to an instance, and a static method is one that does not require an instance to be invoked.