A class declaration is a blueprint for what a class will look like, the data members it will contain, and the functions it will have. In C++ a class declaration is typically made in a "header file" or "include file." A class declaration is essentially an interface specification that says what a class will look like and what it does rather than how it does it.

Java does not have pure declarations like C++ does, and, indeed, it is possible in C++ to combine declaration (interface) with definition (implementation) in the same portion of code.

Take these two examples. The first is a C++ class declaration. It tells the compiler that "this is what an eggTimer looks like and what it can do":

• class eggTimer {
• public:
• int timeEgg (int t);
• private:
• void ringBell();
• };

It does not say anything about exactly how the egg will be timed...