Thread: recursion code

As I am very new to Java Programming, I'd like to make sure that this code is right!
I was trying to make a program that computes the factorial of an input integer (args[0]) using a recursive method factorial():
The following is my program

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

int k=Integer.parseInt(args[0]);
System.out.println(k + " factorial is " + factorial(k));

}
static double factorial(int n) {
if (n==1) return 1;
else return n*factorial(n-1);

}

}



I hope i have written it right, however when I complile and run, there is an Exception "Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 0". I tried changing static type to double and long. I also tried adding "import java.util*;" What difference would it make to this program? can someone please help, thanks.

when I complile and run, there is an Exception "Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 0"

The array you are trying to index has no elements in it. The length is zero. The first element at 0 does not exist.
You need to pass a commandline argument to your program
the program should test if the array that is passed to the main method is empty and if so print out a message and either exit or set a default value for the rest of the code to use.

Initialize the length of your array first and use while statement other than if statement..there are a lot of errors of the program..
I can fix it..let's do it in private if you want..
email me on macabudbudcyril@yahoo.com..I am willing to help for free..

If this is a student assignment you should not be doing the OPs work.

I'm just trying to give more ideas to make it more interesting..peace..

.let's do it in private if you want..

I was referring to that part of your post.
Why not keep it all on the forum so everyone can benefit?

Originally Posted by Norm

The array you are trying to index has no elements in it. The length is zero. The first element at 0 does not exist.
You need to pass a commandline argument to your program
the program should test if the array that is passed to the main method is empty and if so print out a message and either exit or set a default value for the rest of the code to use.

Thank you very much, I noticed it is very simple after this as I learned how to pass an argument through net beans properties bar!

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

int theNum, theFact;

System.out.println("This program computes the factorial " +
"of a number.");
System.out.print("Enter a number: ");
theNum=Console.in.readInt();

theFact = fact(theNum);

System.out.println(theNum + "! = " + theFact + ".");
}

you not yet dicribe [n] value