Thread: method inside main()

Hi,
In structured programming language like c we could create a method in main().In java its not possible.Why? Or is there any way we can create a method in main using keywords like static or something of that sort.

class A{
public static void main(String args[]){
System.out.println("In main()  ");
 
met();
 
void met(){
System.out.println("In met()   ");
 
}
 
}
 
}

Output:

In main()
Exception in thread "main" java.lang.RuntimeException: Uncompilable source code - Erroneous sym type: met
at A.main().java:5

BUILD SUCCESSFUL (total time: 3 seconds)


Yes i know if we place the met() method outside main() and within class A scope then it will run.But cant we do it like a simple c program with methods inside main.I don't need to know what can be the use of it.But can we do it in any other way or not?Let
me know if there is any possible way.

Thanks in advance

Please use the code tags or highlight tags. Also, please properly format your code. It's much easier to read when it has the proper spacings and tabbings.

I've never heard of being able to define a function inside of another function in C or C++. There are closures/lambda functions in the new C++0x language specifications, but I would consider those to operate differently.

You can declare function prototypes inside of another method, but personally I don't see any practical applications of that (typically you want to declare function prototypes either in an external header file, or at the top of your source file).

Since Java does not require you to declare a method "above" the point where you use it, there is no need to declare a method prototype.

// the function prototype is necessary in C/C++ to tell the compiler that such a method exists
void doIt(void);
 
int main(void)
{
     doIt();
}
 
// ... doIt() is defined somewhere below main in the source, but is NOT inside of another function
void doIt(void)
{
    std::cout << "doIt" << std::endl;
}

alternatively, simply switch the order of the function declarations/definitions and you won't need any prototype at all.

// no function prototype is required since doIt is declared and defined before it's used. This won't work if there's a mutual dependency, you'll need to use function prototypes if there are mutual dependencies.
// again, doIt's definition is not inside of any other function
void doIt(void)
{
    std::cout << "doIt" << std::endl;
}
 
int main(void)
{
     doIt();
}

This same idea is instantly captured in Java because the ordering of method declarations/definitions is not important.

Originally Posted by rohan22

But cant we do it like a simple c program with methods inside main

Of course you can, you just need to compile your code. Oh wait, no you can't! I guess you cannot have a method inside another method then. The reason Java cannot do what C can is because it is Java not C. If you want a programming language that does things like C then use C.