In both cases the display reads 7. RPN is in many areas superior to an algebraic calculator, just as OOP is in many areas superior to procedural languages. Java will not sound the death knell of structured programming. It will, however, give programmers a viable choice. Classes Classes are the backbone of Java.
Classes are the manner in which objects are created and modified.
When you create an instance of a class, you create an object. Classes have methods and inheritance the same as objects. In many ways classes are merely objects by another name. To use a class, the class must be declared and constructed. By this I mean the first step in utilizing a class in a Java program is to declare it.