Constructors in Java with example

Constructors in Java

It would be simpler and more concise to initialize an object when it is first created, Java supports a special type of method that enables an object to initialize itself when it is created which is called Constructor.

Rule of Constructors in Java

1. The constructor has the same name as the class itself.
2. A constructor doesn’t specify a return type, not even void.
3. In Java, a constructor can’t be abstract, final and static.

Example:

class square
{
int length, width;
square(int x, int y) // creating constructor
{
length=x;
width=y;
}
int area()
{
return(length*width);
}
}

Types of Constructors in Java

1. Default Constructor
2. Parameterized Constructor

Default Constructor:

When a constructor doesn’t have any parameter, then it is called Default Constructor.

Example:

class Car
{
Car() // Default Constructor
{
System.out.println("Car is moving");
}
public static void main(String args[])
{
Car c1=new Car(); // Calling Default Constructor
}
}

Output:
Car is moving

Parameterized Constructor:

A constructor which has a specific number of parameters is called a parameterized constructor.
Example:

class Integer
{
int n;
Integer(int e) // Parameterized Constructor
{n=e;}
void Palindrome()
{
int rem, q, rev=0;
q=n;
while(n!=0)
{
rem=n%10;
rev=(rev*10)+rem;
n=n/10;
}
if(q==rev)
{
System.out.println("It is a Palindrome Number");
}
else
{
System.out.println("It is Not a Palindrome Number");
}
}
}
public class Test
{
public static void main(String args[])
{
Integer i1=new Integer(121);
i1.Palindrome();
}
}

Output:
It is a Palindrome Number