There are no global variables in Java

Q: Why are there no global variables in Java?

Answer: Global variables are considered bad form for a variety of reasons:

• Adding state variables breaks referential transparency (you no longer can understand a statement or expression on its own: you need to understand it in the context of the settings of the global variables).
• State variables lessen the cohesion of a program: you need to know more to understand how something works. A major point of Object-Oriented programming is to break up global state into more easily understood collections of local state.
• When you add one variable, you limit the use of your program to one instance. What you thought was global, someone else might think of as local: they may want to run two copies of your program at once.

For these reasons, Java decided to ban global variables.
here are three kinds of variables in Java: