Instance Variable in Java

In any programming language, the program needs identifiers for storing different values that can be used throughout the program. These identifiers are variables.

Variable in Java

• A variable is a name assigned to a value that is stored inside the system memory. The value can be updated during the program execution.
• In Java programming, the variables used for the program need to declare them first.
• The variable is declared using a data type followed by the identifier name. The variable can be initialized at the time of declaration or it can be assigned a value taken from the user during the program execution.
• There are basically three types of variables in Java,
  1. Java Local variable
  2. Java Instance variable
  3. Java Static variable / Java class variable

Java Instance Variable

• The variables that are declared inside the class but outside the scope of any method are called instance variables in Java.
• The instance variable is initialized at the time of the class loading or when an object of the class is created.
• An instance variable can be declared using different access modifiers available in Java like default, private, public, and protected.
• Instance variables of different types have default values that are specified in the next point.

Features

1. To use an instance variable an object of the class must be created.
2. An instance variable is destroyed when the object it is associated with is destroyed.
3. An instance variable does not compulsory need to be initialized.
4. Instance variables are accessible inside the same class that declares them.

Limitations of Instance Variable

1. It cannot be declared static, abstract, striftp, synchronized, and native.
2. It can be declared final and transient.
3. It can be of any of the four access modifiers available in Java (private, public, protected, and default).

Default Values of Instance Variables in Java

The instance variables in Java are of different data types as follows;

Let's use instance variable in Java program.

Using Instance Variable in a Java Program

In the following Java program, a class Studentsrecords is declared and instance variables are created using different access modifiers.

Studentsrecords.java

Output:

Student Name: Monica
Student Division: B
Student Age: 14

The above Java program initializes the instance variables by declaring an object of the class Studentsrecords. The values of instance variables name, division, and age are displayed using printstud() method.

Difference between Local, Instance and Static variables in Java