Hi all,

I have written following code.

public class Sample {
public static void main(String[] argv) {
System.out.println("Class Sample");
}

}

public class S {
public static void main(String[] argv) {
System.out.println("Class S");
}
}

I have saved the code in the file with name Sample.java . If I compile, it will print Class Sample. I know that file(program) can have only one public class. Now my doubt is how single program can have two different main() methods. Is it leagal in java.....?

Thanks & Regards,
Abhijit

Hi Abhijith,

If u want to use more than one main method in a single pgm, make use of overriding concept.

Here is the eg:

class test
{
public static void main(String args[])
{

System.out.println("welcome ");
}
}
class test1 extends test
{
public static void main(String args[])
{
System.out.println("geekinterview member");
}

}
class javaapplication1
{
public static void main(String args[])
{
String S[]=new String[10] ;

test.main(S);
test1.main(S);
}
}

It ll give the output:
welcome
geekinterview member

Regards,
Rijus.

Hi Abhi,

In a .java file each class can have its main() method, calling of the main() method by JVM depends on the given execution command

In given example if we execute using following command

java Sample

then Sample class's main() method will be executed.

and if command is

java S

then S class's main() method will be executed.

The only benefit I can see in defining main() method in every class is we can execute each class.

A class can not have multiple main() methods but a file can have as many main() methods as it has classes.

hope it would help you

Hi Rijus,

But is it legal to override main() method

Hi Ravi,

One possible purpose of having multiple Main methods( overriding concept) in each class in a single source file is for debugging purposes.

For the same reason, some Java developers like to write main methods for multiple classes within the same package, even though only one of them is meant to be executed.

Regards,
Rijus.