Java™ How To Program (Early Objects), Tenth Edition

static Methods Cannot Directly Access Instance Variables and Instance Methods

A static method cannot access a class’s instance variables and instance methods, because a static method can be called even when no objects of the class have been instantiated. For the same reason, the this reference cannot be used in a static method. The this reference must refer to a specific object of the class, and when a static method is called, there might not be any objects of its class in memory.

Common Programming Error 8.5

A compilation error occurs if a static method calls an instance method in the same class by using only the method name. Similarly, a compilation ...