The Fibbonacci Series

The Fibbonacci Series

   March 31, 2018       Unknown

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Write a program in an applet that enables a user to input an integer in a textfield and the applets indicates the ith Fibonacci number to calculate.

The Fibonacci series begins with 0 and 1 and has the property that each subsequent Fibonacci number is the sum of the previous two Fibonacci numbers.

The Fibonacci series may be defined recursively as follows:
fibonacci(0) = 0
fibonacci(1) = 1

fibonacci(n) = fibonacci(n-1) + fibonacci (n-2)

The Program

import java.awt.*;
import java.awt.event.*;

import javax.swing.*;

public class FibonacciTest extends JApplet implements ActionListener {
 JLabel numberLabel, resultLabel;                     //initialize variable for the gui
 JTextField numberField, resultField;

 //set up gui (Graphics User Interface)
 public void init()
 {
  Container container = getContentPane();
  container.setLayout(new FlowLayout());

  //create numberLabel and attach it to the content pane
  numberLabel = new JLabel ("Enter an integer and press Enter");
  container.add(numberLabel);

  //create numberField and attach it to the content pane
  numberField = new JTextField(10);
  container.add(numberField);

  //register this applet as numberField's ActionListener
  numberField.addActionListener(this);

  //create resultLabel and attach it to the content pane
  resultLabel = new JLabel("Fibonacci Value is");
  container.add(resultLabel);

  //create resultField and attach it to the content pane
  resultField = new JTextField(15);
  resultField.setEditable(false);
  container.add(resultField);

 }

 //obtain user input and call method fibonacci
 public void actionPerformed (ActionEvent event)
 {
   //Fibonacci numbers tend to become large quickly, therefore, we use long as the parameter type and return type of the Fibonacci.

  long number, fibonacciValue;

  //obtain user's input and convert to long
  number = Long.parseLong(numberField.getText() );

  showStatus("Calculating.........");

  //Calculate fibonacci value for number input
  fibonacciValue = fibonacci(number); //method fibonacci is called here

  //indicate processing complete and display result
  showStatus("Done!");
  resultField.setText(Long.toString(fibonacciValue) );
 }


 public long fibonacci(long n) //Note n is the number chosen to represent number in method fibonacci(number);
 { //Note all method that has the arguments long, int, double, float must return its answer to the called method.
  //base case
  if(n== 0 || n == 1)
   return n;

  //recursive step
  else
   return fibonacci(n-1) + fibonacci(n-2);


 }

}