Types Of Variables in Java With Example

Variable in Java is a data container that stores the data values during Java program execution. Variable is a memory location name of the data. . Every variable is assigned data type which designates the type and quantity of value it can hold. The Java variables have three types of variables - local, instance and static.

To indicate the storage area, each variable should be given a unique name (identifier).

1.      Variable Declaration

2.    Variable Initialization 

Variables Declaration in Java

Here's how we create a variable in Java, To declare a variable, you must specify the data type & give the variable a unique name.

Examples of other Valid Declarations are

int var ;
float floatvar;
double doublevar;

 

Note – int , float , double are data types and after that var, floatvar , doublevar are variable name you can put any others name as you want according data types :

 

Variable

Variable is name of reserved area allocated in memory. In other words, it is a name of memory location. It is a combination of "vary + able" that means its value can be changed.

 

Variable Initialization:

To initialize a variable, you must assign it a valid value.

Example of other Valid Initializations are

var = 89;
floatvar = 89.98f;
doublevar = 76.9;

 

You can combine variable declaration and initialization.

int var = 89;
float floatvar = 89.98f;
double doublevar = 76.9;

 

Change values of variables

The value of a variable can be changed in the program, hence the name variable. For example,

 


// before
        int var = 89;
        float floatvar = 89.98f;
        double doublevar = 76.9;

        // after
       
        int var = 898;
        float floatvar = 879.98f;
        double doublevar = 976.9;

 

Rules for Naming Variables in Java

Java programming language has its own set of rules and conventions for naming variables. Here's what you need to know:

Java is case sensitive. Hence, age and AGE are two different variables. For example,

int age = 8;
int Age = 87;

 

Variables must start with either a letter or an underscore, _ or a dollar, $ sign. For example,

int Age = 8;
int _Age = 87;
int $Age = 87;

Variable names cannot start with numbers. For example,

int 1Age = 8;

 

Variable names can't use whitespace. For example,


int _Age Rahul = 87;

There are types of variables in Java programming language:

  • Instance Variables (Non-Static Fields)
  • Class Variables (Static Fields)
  • Local Variables
  • Parameters

 

1) Local Variables

Local Variables are a variable that are declared inside the body of a method. A local variable declared inside the body of the method is called local variable. You can use this variable only within that method and the other methods in the class aren't even aware that the variable exists.

A local variable cannot be defined with "static" keyword

 

2) Instance Variables

A variable declared inside the class but outside the body of the method, is called instance variable. It is not declared as static.

It is called instance variable because its value is instance specific and is not shared among instances.

 

3) Static Variables

Static variables are initialized only once, at the start of the program execution. These variables should be initialized first, before the initialization of any instance variables.

 

Example: Types of Variables in Java

static int ab = 91; //static variable 
int intiger = 7; //instance variable 
void method() {
    int a = 9; //local variable 

 

 

Java literals

Literals are data used for representing values. They can be used directly in the code. For example,

int var = 89;
float floatvar = 89.98f;

 

Here, 89, 89.98f,  are literals.

Here are different types of literals in Java.

 

1. Boolean Literals

In Java, boolean literals are used to initialize boolean data types. They can store two values: true and false. For example,

boolean holiday = false;
boolean holiday = true;

 

2. Integer Literals

An integer literal is a numeric value. There are 4 types of integer literals in Java:

1.    binary (base 2)

2.    decimal (base 10)

3.    octal (base 8)

4.    hexadecimal (base 16)

 

For example:


        // binary Number
        int binaryNumber = 0b110;
// octal  Number
        int OctalNumber = 027;

// decimal Number
        int DecNumber = 34;

// hexadecimal Number
        int HexNumber = 0x2Fsd3; // 0x represents hexadecimal
// binary
        int BinNumber = 0b010; // 0b represents binary

 

In Java, binary starts with 0b, octal starts with 0, and hexadecimal starts with 0x.

 

3. Floating-point Literals

A floating-point literal is a numeric. For example,

 

float $Age = 87.6f;
double doublevar = 976.9;

 

 

4. Character Literals

Character literals are unicode character enclosed inside single quotes. For example,

 

char A = 'a';

 

 

5. String literals

A string literal is a sequence of characters enclosed inside double-quotes. For example,

 

String var = "Programming";
String va2 = "androidpro.in";

 

Here, Programming and androidpro.in are two string literals.