Facts about Constructor with an example...............

Some facts that you should know about Constructor.....................

• It has the same name as the classname.
• It is used to initialize the object that means it is used to construct the object.
• It does not have any return type.
• It can have arguments.
• The constructor without argument is called default constructor.
• A class can have more than one constructor but they must be different from each other by  

     - Number of arguments or
     - Type of arguments or
     - Sequence of arguments
This concept is called constructor overloading.  

• It is automatically called when an object is created.

Simple example to explain constructor in program.

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import java.io.*;

class cons

{

int a,b;

cons()//defulat constructer

{

a=10;

b=20;

System.out.println("default constructer");

}

cons(int p,int q)//parametrised constructer

{

a=p;

b=q;

System.out.println("parametrised constructer");

}

cons(int p)//one parametrised constructer

{

a=p;

b=25;

System.out.println("one parametrised constructer");

}

void show()

{

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

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

}

public static void main(String arg[])throws IOException

{

cons c1=new cons(); 

c1.show();

cons c2=new cons(10); 

c2.show();

cons c3=new cons(100,200); 

c3.show();

cons c4=new cons(); 

c4.show();

cons c5=new cons(); 

c5.show();

cons c6=new cons(1000,2000); 

c6.show();

cons c7=new cons(5000,10000); 

c7.show();

}

}