Thread: Recursion help

Hi everyone, so I'm still trying to figure out how to get my recursive function to work to calculate my sine so I figured I'd start with a factorial function and work my way up, adding the necessary parts. I looked at http://www.javaprogrammingforums.com...-concepts.html but I can't get any of the code to work.

I get these errors

ftest.java:1: class, interface, or enum expected
public static int interativeFactorial(int n)
              ^
ftest.java:4: class, interface, or enum expected
        for(int i = 1; i < n; i++)
        ^
ftest.java:4: class, interface, or enum expected
        for(int i = 1; i < n; i++)
                       ^
ftest.java:4: class, interface, or enum expected
        for(int i = 1; i < n; i++)
                              ^
ftest.java:7: class, interface, or enum expected
        }
        ^
ftest.java:9: class, interface, or enum expected
}
^
6 errors

All I'm using is

public static int interativeFactorial(int n)
{
        int answer = 1;
        for(int i = 1; i < n; i++)
        {
                answer *= i;
        }
        return answer;
}
}

I've tried adding in

public class ftest
{
public static int interativeFactorial(int n)
{
        int answer = 1;
        for(int i = 1; i < n; i++)
        {
                answer *= i;
        }
        return answer;
}
}

but then I get the error

Exception in thread "main" java.lang.NoSuchMethodError: main

so then I tried putting in

public class ftest
{
public static void main(String args[])
{
public static int interativeFactorial(int n)
{
        int answer = 1;
        for(int i = 1; i < n; i++)
        {
                answer *= i;
        }
        return answer;
}
}
}

then I just get more errors!

ftest.java:5: illegal start of expression
public static int interativeFactorial(int n)
^
ftest.java:5: illegal start of expression
public static int interativeFactorial(int n)
       ^
ftest.java:5: ';' expected
public static int interativeFactorial(int n)
             ^
ftest.java:5: '.class' expected
public static int interativeFactorial(int n)
                                          ^
ftest.java:5: ';' expected
public static int interativeFactorial(int n)
                                           ^
5 errors

I'm pretty lost about what to do at this point if I can't even get this to compile and work right. Any clarification would be appreciated!

First off this is not recursion, you are using a loop, recursion relies on recalling the same method until some condition is met.

Your code, although not recursion is fine, except you need a main method. All classes are a series of methods, main is the entry point of a program. You don't define a method in main, instead you call methods in main. Methods are created outside of the main method

public class blah{
  public static void hello(){
    System.out.println("hello");
  }
  public static void main(String[] args){
    hello();
  }
}

Try compiling and runnning that and see if it helps you a bit with what you did wrong in your code.

This is an example of a program to recursively add two numbers.

public class Add{
  public static int add(int x, int y){
    if(y == 0){
      return x;
    }
    else{
      return add(x + 1, y - 1);
    }
  }
  public static void main(String[] args){
    System.out.println(add(5, 6));
  }
}

Originally Posted by sunde

First off this is not recursion, you are using a loop, recursion relies on recalling the same method until some condition is met.

Your code, although not recursion is fine, except you need a main method. All classes are a series of methods, main is the entry point of a program. You don't define a method in main, instead you call methods in main. Methods are created outside of the main method

public class blah{
  public static void hello(){
    System.out.println("hello");
  }
  public static void main(String[] args){
    hello();
  }
}

Try compiling and runnning that and see if it helps you a bit with what you did wrong in your code.

Thanks for clarifying that, I stated that it was recursion based off the topic of the tutorial I found the code in. The example code was very helpful to show how recursion actually works. I think I understand why it didn't work now. I'm still pretty new to java and all, so thanks you for all your help!