Reference Variables: In Java, a reference variable is a variable that holds the memory address of an object rather than the actual object itself. It acts as a reference to the object and allows manipulation of its data and methods. Reference variables are declared with a specific type, which determines the methods and fields that can be accessed through that variable.
Here’s an example that demonstrates the concept of reference variables in Java:
Reference variables example - car properties
public class Main{
public static void main(String[] args) {
// Declare a reference variable of type Car
Car myCar;
// Create a new Car object and assign its reference to myCar
myCar = new Car();
// Access and modify the object's properties
myCar.brand = "Toyota";
myCar.year = 2021;
// Use the reference variable to perform actions on the object
System.out.println("Brand: " + myCar.brand);
System.out.println("Year: " + myCar.year);
}
}
class Car {
String brand;
int year;
}
Output
Brand: Toyota
Year: 2021
In the example above, we declare a reference variable called myCar of type Car. Then, we create a new Car object using the new keyword and assign its reference to myCar. After that, we can use the myCar reference variable to access and modify the object’s properties (brand and year) as well as perform actions on the object.
Benefits and Usage of Reference Variables
Object Manipulation: Reference variables allow programmers to work with objects, access their properties, and invoke their methods. They enable object-oriented programming principles such as encapsulation, inheritance, and polymorphism.
Memory Efficiency:Reference variables only store the memory address of an object rather than the entire object itself. This approach helps conserve memory by avoiding unnecessary object duplication.
Object Passing: Reference variables are often used when passing objects as arguments to methods or returning objects from methods. This allows for efficient memory usage and facilitates modular programming."
Tutorialsbox