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Java Variables With Types and Examples

Java Variables: In this tutorial, we are going to learn about the variables, various types of variables in Java. By Karan Ghai Last updated : January 02, 2024

Java Variables

Java variables are the user-defined names of the memory blocks, and their values can be changed at any time during program execution. They play an important role in a class/program as they help in to store, retrieve a data value.

Declaring a variable

To declare a variable, write the variable name followed by the type and assign a value (if you want to initialize it).

Syntax

type variable_name;
type variable_name = value;

Types of Java Variables

There are three types of Java variables,

1. Instance Variables
2. Local Variables
3. Class/Static Variables

1. Java Instance Variables

• Instance variables are declared in a class but outside a Method, Block or Constructor.
• Instance variables have a default value 0.
• These variables can be created only when the object of a class is created.

Java example of instance variables

public class Bike {
    public String color;

    Bike(String c) {
        color = c;
    }

    public void display() {
        System.out.println("color of the bike is " + color);
    }

    public static void main(String args[]) {
        Bike obj = new Bike("Red");
        obj.display();
    }
}

Output

Color of the bike is Red

2. Java Local Variables

• Local variables are the variables which are declared in a class method.
• We can use these variables within a block only.

Java example of local variables

public class TeacherDetails {
    public void TeacherAge() {
        int age = 0;
        age = age + 10;
        System.out.println("Teacher age is : " + age);
    }

    public static void main(String args[]) {
        TeacherDetails obj = new TeacherDetails();
        obj.TeacherAge();
    }
}

Output

Teacher age is : 10

3. Java Class/Static Variables

• This can be called Both Class and Static Variable.
• These variables have only one copy that is shared by all the different objects in a class.
• It is created during the start of program execution and destroyed when the program ends.
• Its Default value is 0.

Java example of class/static variables

public class Bike {
    public static int tyres;
    public static void main(String args[]) {
        tyres = 6;
        System.out.println("Number of tyres are " + tyres);
    }
}

Output

Number of tyres are 6