Java

Variables in Java

A variable is a memory location that is responsible for holding data values while a Java program is being executed. A datatype is assigned to variables which tells the type and value the variable will hold. In general, Java variables can be divided into given types.

  1. Local
  2. Instance
  3. Static

Let’s discuss these variables in detail.

1. Local Variables

A local variable is specified inside a method however, other methods in the class have no access to this variable.

2. Instance Variables

Instance variables are specified outside a method but within the class and without the using the keyword static. Since these variables have instance-specific values so these are called instance variables.

3. Static Variables

Static variables are specified only once and shared wih other instances of a particular class. Moreover, these are declared at the start of the program execution.

Here is an example.

class LearningVariables {
       static int x =10; //This is a static variable
       int y = 15; // This is an instance variable
       void method ( ) {
              int z = 20; // This is a local variable
   }
}

Before you begin working with Java variables you need to be aware of two variable relevant concepts and these are:

1. Variable Declaration

Variable declaration is the procedure of specifying the data type and unique name of the variable.

Syntax:

datatype variable name;

Examples:

1. int age;

2. float pi;

3. double area;

4. char flag;

2. Variable Initialization

Variable initialization is the procedure of giving an authentic value to the variable.

Syntax

name = variable value;

Examples

1. age=25;

2. pi=3.14;

3. area=32345.65;

4. char= 'a';

Java Variable Types

Java variables can also be categorized by the type of value they store in them. On the basis of the value stored, Java variables can be classified into the following types.

  1. string
  2. int
  3. float
  4. char
  5. boolean

These are discussed in detail below.

1. string
String store text and these are always written inside inverted commas. For example,

string name= "John Doe";

2. int
Int variables store whole numbers. For example,

int num= 24;

3. float
Float is used to store decimal numbers. For example,

float pi= 3.14;

4. char
Char variables are used to store single characters and these are always written inside single quotes. For example,

char x='a';

5. boolean
Boolean variable store values that are either true or false.

boolean flag=true;

Conclusion

Variables are entities that store data values while a Java program is being executed. Java variables, in general, are of three types that are local variables, instance variables, and static variables. Java variables can also be classified into categories on the basis of the type of value they store such as string, int, float, char, and boolean. All of these variables along with suitable examples are explained in detail in this write-up.

About the author

Naima Aftab

I am a software engineering professional with a profound interest in writing. I am pursuing technical writing as my full-time career and sharing my knowledge through my words.