Constructors in Java programming| Zhullyblog

CONSTRUCTORS

In this tutorial, you would learn about constructurs in Java programming.

A constructor in Java is a block of code that is similar to a method that's invoked when an instance of an object is created .

Note:A constructor is not the same as a method but it's quite similar to method. A constructor must have the same name with the class name and must not return any value.

Take a look at this;

class Sample {

void Sample() {

// method body

}

Sample( ) Is a constructor. It has exactly the same name as the class name and have no return type. Let's take an example.

class Sample {

private int x;

// The constructor

private Sample(){

System.out.println("This is the constructor");

x = 5;

}

public static void main(String[] args){

// Here we will call the constructor

Sample obj = new Sample();

System.out.println("Value of x = " + obj.x);

}

Snippet

Types of constructor

There are two different types of constructor namely;

NO ARGUMENT

PARAMETERIZED

NO ARGUMENT:When a constructor does not accept parameters,it is known as NO ARGUMENT constructors. A NO ARGUMENT constructors is quite similar but entirely different from default constructor. The body of a default constructor is empty but a NO ARGUMENT can have any code.

Here is an example

class Main {

int x;

// constructor with no parameter

private Main(){

// body of the constructor

x = 5;

System.out.println("x = " + x);

}

public static void main(String[] args) {

// calling the constructor with no parameter

Main obj = new Main();

}

Screenshot

PARAMETERIZED:A constructor that accept a parameter is known as a parameterized constructor. Unlike the NO ARGUMENT constructor that doesn't accept any argument. Parameterized constructor accept argument. In parameterized constructor, the parameters to be added are declared inside the parenthesis after the constructors name.

Let's take an example

class Staff {

int code;

// constructor accepting single value

private Staff(int age){

this.code = code;

System.out.println(code + " staff .");

}

public static void main(String[] args) {

// calling the constructor by passing single value

Staff s1 = new Staff(2);

Staff s2 = new Staff(3);