Problem

Write a complete Java program Fibonacci that:

• prompts the user to enter an input n and cast it to integer
  
• get the nth fibonacci numbers using FOR loop, based on the user's input
  
• prints out the nth fibonacci number, using JOptionPane.showMessageDialog method.
  

Note that the fibonacci sequence is F(0) = 1, F(1) = 1, F(n) = F(n-1) + F(n-2) for n > 1.
Example: F(5) = 1, 1, 2, 3, 5, 8
Your output should look something like
"The 5th number of the fibonacci sequence is 5."

You may assume that the user always enters correct intenger format.

...by students

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Solution

 
In order to get the user input by JOptionPane, you will first have to import the swing package.
You can import swing package by 
import javax.swing.*; or import javax.swing.JOptionPane;

Then, the next step would be declaring variables; in this program we will need only two int variables.
current will be F(n) and previous will be F(n-1). Do NOT forget to declare them outside the for loop.

Code

Solution Code

import javax.swing.JOptionPane;

public class Fibonacci
{
    public static void main(String[] args)
    {     	
 		int current = 1;
 		int previous = 0;

		int n = Integer.parseInt(JOptionPane.showInputDialog("Please enter n"));

 		for(int i = 0; i < n; i++)
                {
 			int temp = previous;
 			previous = current;
 			current = temp + previous;
 		}
 		
 		JOptionPane.showMessageDialog(null, "The " + n + "th Fibonacci number is " + current);
    }
}