Constructor in Java

Constructor In Java

Constructor is a special method that is used to initialize objects in Java. It is called when we create the object of a class. It can be used to set initial values for objects.

Rules For Creating Java Constructor

Constructor name must be the same as its class name.
Constructor does not have any return type.
Constructors are only called once at object creation.

Example

class Computer{
    // properties
    int id;
    String name;
    double price;

    // constructor
    public Computer(int id, String name, double price) {
        this.id = id;
        this.name = name;
        this.price = price;
    }
    // methods
    void printDetails(){
        System.out.println("ID is "+this.id);
        System.out.println("Name is "+this.name);
        System.out.println("Price is "+this.price);
    }

}
// Main class
public class Main {
    // main method
    public static void main(String[] args) {
        //Creating a object from class Computer. We must give parameter value here
        Computer com1 = new Computer(1, "MSI",233.0);
        // Assign value to class properties
        System.out.println(com1.id);
        System.out.println(com1.name);
        System.out.println(com1.price);
    }
}

Constructor Overloading In Java

Constructor overloading in Java is a technique of having more than one constructor with different parameter lists. They are arranged in a way that each constructor performs a different task. The compiler differentiates them by the number of parameters in the list and their types.

Example

class Computer{
    // properties
    int id;
    String name;
    double price;

    // constructor
    public Computer(int id, String name, double price) {
        this.id = id;
        this.name = name;
        this.price = price;
    }
    public Computer(int id, String name) {
        this.id = id;
        this.name = name;
        this.price = 0;
    }
    // methods
    void printDetails(){
        System.out.println("ID is "+this.id);
        System.out.println("Name is "+this.name);
        System.out.println("Price is "+this.price);
    }

}
// Main class
public class Main {
    // main method
    public static void main(String[] args) {
        //Creating a object from class Computer. We must give parameter value here
        Computer com1 = new Computer(1, "MSI",233.0);
        // Assign value to class properties
       com1.printDetails();
    }
}

Show Output