Fibonacci Generators and the loop commands.

[Brandon Choate]

Hello!

I'm trying to create a program that uses the Fibonacci series.
You are supposed to be able to input a number into the program, then use a while or for loop to keep adding the number for the fibonaci generator.

   import javax.swing.JOptionPane;
/*
 Tests the FibonacciGenerator program 
 */
public class FibonacciGeneratorTest
{ 
  public static void main(String[] args)
   {
	 String n = JOptionPane.showInputDialog
	 ("Enter a Number or hit ''Cancel'' to exit:");
    n = n.toUpperCase();

FibonacciGenerator aFibonacciGenerator = new FibonacciGenerator();


while ()
{ aFibonacciGenerator.nextNumber();
 }

 
 System.out.println(n); 

.... and here is the other half.

   public class FibonacciGenerator
{ 
 /* Construct a FibonacciGenerator object
  to generate a Fibonacci number. */
public FibonacciGenerator()
 { 
 fold1 = 1;
 fold2 = 1;
 fnew = 1;
 count = 0;
  }
 
 /** Method used to calculate a fibonacci number */
 public int nextNumber()
   { if(count < 2)
	  { count++;
	  return 1; 
	  }
	  else 
	   { 
		 fnew = fold1 + fold2;
		 fold2 = fold1;
		 fold1 = fnew;
		 return fnew;
	   }  
	} 

/* Instance Fields */
private int fold1;
private int fold2;
private int count;
private int fnew;

                 } 

This is what I have so far. Where should I go from here? the "while" command doesn't recognize anything from the second program.

On a related note, how would I be able to get the program to loop back around and ask for another number after it is finished with the calculations?

[Larry Frissell]

1) Your while loop needs a boolean condition, like while(x>5).
2) you are not doing anything with the int return from nextNumber()
3) it is not clear what you are doing with n ( other than printing it)

Try this, but this will only print " while loop ", this will get you started, but you will need to think about where you want the program to go from here.

public class FibonacciGeneratorTest {
    Boolean t = true;
 public static void main(String[] args)
   {
     String n = JOptionPane.showInputDialog
     ("Enter a Number or hit ''Cancel'' to exit:");
    n = n.toUpperCase();
new FibonacciGeneratorTest().dostuff();
System.out.println(n);
 }
public void dostuff(){
    FibonacciGenerator aFibonacciGenerator = new FibonacciGenerator();
while (aFibonacciGenerator.nextNumber()<50)
{
    System.out.println("while loop ");
 }

 }
}    

[Varun Goenka]

let me suggets a far simpler algorithm.
Declare 2 variables t1 and t2 with values 0 and 1 respectively.
Then within the loop write this
{
t3=t1+t2;
t2=t3;
t1=t2;
}

Let the loop work till accepted value is less than t3.

Simple isnt it. .
No sweat.

[Brandon Choate]

Thanks! That helped quite alot!

My new program now looks like:

  import javax.swing.JOptionPane;
/*
 Tests the FibonacciGenerator program 
 */
public class FibonacciGeneratorTest
{ double n;
  public static void main(String[] args)
   {
	 String n = JOptionPane.showInputDialog
	 ("Enter a Number or hit ''Cancel'' to exit:");
    n = n.toUpperCase();
	 
new FibonacciGeneratorTest().doCalculation();

	System.out.print("Fib(");
   System.out.print(n);
   System.out.print(") =" );
	System.out.print(" ");

}
public void doCalculation()
{
 FibonacciGenerator aFibonacciGenerator = new FibonacciGenerator();
 while (aFibonacciGenerator.nextNumber()<n)
            {
				System.out.println(aFibonacciGenerator.nextNumber());
				}
		
  }
   }  

If I were to input the number 3, it'd output "fib(3) = ".
Problem is, I can't get the the last number to output after the equals sign (in this case, it'd be 2).

">

[Larry Frissell]

Have you tried running the code? I ask because there appears to be some issues you have not addressed. "n" is declare as a double, then as a String within the main method. Since the double n is not initialized, I do not think the loop will end

I would suggest taking this one step at a time, first looking at what your while loop is doing and using some System.out.print() statements to see if the loop is doing what you expect.