Java Variables3 min read

What is Variable in Java?

The variable is the basic unit of storage which holds the value while the program is executed. We can also say that it is a name given to the memory location. A variable is defined by data-types provided by Java.
It may be string, int, float, char, and boolean.

Declaring a Variable in Java:

Certain rules are needed to be followed before declaring the variables:

  • The first character must be a letter.
  • A variable name can consist of letters A-Z, a-z, digits 0-9, and two special characters such as underscore(_) and dollar Sign($).
  • Blank spaces cannot be used in variable names.
  • Java keywords cannot be used as variable names.
  • Variable names are case-sensitive.

Syntax to declare Variables:

Here, data_type means one of the Java data-types mentioned above. variable_name is the name that must be assigned to it, you can give any name suitable for it. The equal sign(=) is an assignment Operator used to assign the value of R.H.S. to L.H.S.

Example: Demonstration of assigning value to different data-types

Types of Variables in Java:

  • local variable
  • instance variable
  • static variable

Following declaration help us to understand the position of each of these three variables:

1. Local Variable:

A variable that is declared within the body of the method or constructor is called a local variable. This variable is used only within that block or method where it was created other classes cannot access it. And is destroyed after exiting the method or block. Initialization of Local Variables is necessary.

Example of Local variable in Java:

Output of local variable in Java:

2. Instance Variable:

These are the non-static variable that is declared within the class but outside the method or constructor. With the creation of Objects, Instance Variable is created and destruction of an object destroys the variables. And can be accessed only by creating objects. Initialization of Instance Variable is not necessary as it is 0 by default.

Example of Instance variable in Java:

Output of Instance variable in Java:

3. Static variable:

These variables are also known as class Variables. These are declared just like Instance Variable that within the class but outside the constructor or method but the difference is that static variable is declared using static keyword. Unlike Instance variable, only one static variable is created its value remains the same for all objects no matter how many objects user creates. Here initialization is not mandatory, it is 0 by default.

Example of Static variable in Java:

Output of Static variable in Java:

Scope of a Variable in Java