With interface reference variable, an object of a class that implemented an interface can reference this name and call the method. The effect is that it's just like you are using the interface ...

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 example, you can start a Java variable with a dollar sign or an underscore -- but nobody does that. Sometimes machine-generated code prepends a dollar sign or underscores a Java variable to ...

Java’s interface feature lets you reference an object without concern for the object’s class type. ... Variables that store references are often called reference variables.