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