Constructor Method in Java

In Java, a constructor method is a special type of method that is automatically called when an object of a class is created using the "new" keyword.

Constructors are used to initialize the newly created object, typically by setting initial values for its attributes or performing other setup tasks.

Here's an overview of constructors methods in Java:

Constructor Declaration:

A constructor method has the same name as the class name in which it is defined.

Constructors do not have a return type, not even void.

Example:

public class YourClass {

    // Constructor method
    public YourClass() {
        // Constructor body
    }

}

Default Constructor:

If a class does not explicitly define any constructors, Java provides a default constructor automatically.

Example:

public class YourClass {

    // Default constructor method provided by Java
    // public YourClass() {
        // Empty Body
    // }

}

The default constructor initializes the object's attributes to their default values (e.g., 0 for numeric types, null for reference types).

Parameterized Constructor:

Example:


public class Vehicle {
    String manufacturer;
    String model;
    int year;

    // Parameterized constructor method
    public Vehicle(String manufacturer, String model, int year) {
        this.manufacturer = manufacturer;
        this.model = model;
        this.year = year;
    }

}

We can define constructors with parameters to initialize object attributes with specific values provided during object creation.

Parameterized constructors allow us to customize the initialization of objects.

Example:

public class Vehicle {
    String manufacturer;
    String model;
    int year;

    // Parameterized constructor method
    public Vehicle(String manufacturer, String model, int year) {
        this.manufacturer = manufacturer;
        this.model = model;
        this.year = year;
    }

}

Example:


class Vehicle {
    String manufacturer;
    String model;
    int year;

    // Parameterized constructor method
    public Vehicle(String manufacturer, String model, int year) {
        this.manufacturer = manufacturer;
        this.model = model;
        this.year = year;
    }

}

public class MainClass {
    public static void main(String[] args) {

    // Pass Argument while creating Instance of Vehicle
    Vehicle vehicle = new Vehicle("Volvo", "XC40", 2022); 
    

    System.out.println("Printing Model launch in which Year: " + vehicle.year);

    }
}

Initializing Object Attributes:

Constructors are commonly used to initialize object attributes to specific values passed as arguments or to perform other setup tasks required for the object.

Inside a constructor, we can use the "this" keyword to refer to the current object being initialized.

Now, if we create an instance of the `Vehicle` class then we need to pass arguments to the `Vehicle` Method so that it will initialize instance attributes of the Vehicle Class.

Output:

Printing Model launch in which Year: 2022

Note:

Constructors play a crucial role in Java programming as they ensure that objects are properly initialized before they are used.

By defining constructors, we can control how objects are created and initialized, ensuring that they are in a valid state for use.

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