Question

This project involves writing a program to calculate the terms of the following sequence of numbers: 0 1 1 3 5 11 21 43 … where each term is twice the second previous term plus the previous term. The 0th term of the sequence is 0 and the 1st term of the sequence is 1.
The example below shows how to calculate the next sequence term:
Current sequence: 0 1 Calculate next term: 2 * 0 + 1 = 1
Current sequence: 0 1 1 Calculate next term: 2 * 1 + 1 = 3
Current sequence: 0 1 1 3 Calculate next term: 2 * 1 + 3 = 5
Current sequence: 0 1 1 3 5 Calculate next term: 2 * 3 + 5 = 11
… etc.

The pair of radio buttons allows the user to choose whether an iterative or recursive method is used to compute the term of the sequence (the Iterative radio button should be initially selected). When the user enters a value for n and then clicks the Compute button, the nth term of the sequence (counting from zero) should be displayed in the Result field. The Efficiency field should contain the number of calls to the recursive method when the recursive option is chosen and the number of iterations of the loop when the iterative option is selected. The program will check the validity of the user input value which should be a positive integer. A message will be shown in a JOptionPane for illegal entered values.
When the window is closed, the efficiency values should be computed with values of n from 0 to 20 and written to a text file outData.txt. Each line of the file should contain the value of n, the efficiency of the recursive method for that value of n and the efficiency of the iterative method. The values should be separated by commas so the file can be opened with Excel and used to graph the value of the efficiencies for both the recursive and iterative options along the y axis and with the value of n along the x-axis. The graph should be included in the solution description document that accompanies this project and should also contain a brief explanation of the observed results.
The program should consist of two classes: P3GUI and Sequence.
1. Class P3GUI should define the Swing based GUI and should be hand-coded and not generated by a GUI generator. In addition to the main method and a constructor to build the GUI, an event handler will be needed to handle the Compute button click and another handler will be needed to produce the file described above when the window is closed. The latter handler should be an object of an inner class that extends the WindowAdapter class.
2. Class Sequence should be a utility class meaning that all its methods must be class (static) methods and no
objects should be able to be generated for that class. It should contain three public methods:
a. The first method computeIterative should accept a value of n and return the corresponding element in
the sequence using iteration.
b. The second method computeRecursive should accept a value of n and return the corresponding element
in the sequence using recursion. This method will initialize the efficiency counter before calling the private
recursive method that will actually perform the recursive computation.
c. The third method getEfficiency will return the efficiency counter left behind by the previous call to either
of the above two methods.

Answer 1

P3GUI.java
------------------------------------------------------------
import java.awt.*;
import java.awt.event.*;
import java.io.FileWriter;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.*;

public class P3GUI extends javax.swing.JDialog implements ActionListener{
    //instance variables
    private final JFrame frame;
    private JPanel panel;
    private final JRadioButton recursiveButton;
    private final JRadioButton iterativeButton;
    private final JButton computeButton;
    private final JTextField nTextField;
    private final JTextField resultTextField;
    private final JTextField efficiencyTextField;
    private static Sequence sequence;

    /**
     *
     * Constructor to create GUI
     */
    public P3GUI(){

        frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        frame.setTitle("Project 3");
        frame.setSize(300,200);
        frame.setLocationRelativeTo(null);
        recursiveButton = new JRadioButton("Recursive");
        iterativeButton = new JRadioButton("Iterative");
        computeButton = new JButton("Compute");
        nTextField = new JTextField();
        resultTextField = new JTextField();
        efficiencyTextField = new JTextField();

        ButtonGroup group = new ButtonGroup();
        group.add(recursiveButton);
        group.add(iterativeButton);
        iterativeButton.setSelected(true);

        iterativeButton.setActionCommand("iterative");
        recursiveButton.setActionCommand("recursive");
        computeButton.setActionCommand("compute");
        iterativeButton.addActionListener(P3GUI.this);
        recursiveButton.addActionListener(P3GUI.this);
        computeButton.addActionListener(P3GUI.this);

        frame.setLayout(new GridLayout(6,2,3,3));

        frame.add(new JLabel(""));
        frame.add(iterativeButton);
        frame.add(new JLabel(""));
        frame.add(recursiveButton);
        frame.add(new JLabel("Enter n: (1-25)"));
        frame.add(nTextField);
        frame.add(new JLabel(""));
        frame.add(computeButton);
        frame.add(new JLabel("Result:"));
        frame.add(resultTextField);
        frame.add(new JLabel("Efficiency:"));
        frame.add(efficiencyTextField);
        frame.addWindowListener(new WindowAdapterImpl());

        frame.setVisible(true);
    }

    public boolean isNumeric(String str){
        try
        {
            double d = Double.parseDouble(str);
        }
        catch(NumberFormatException nfe)
        {
            JOptionPane.showMessageDialog(frame, "Please Enter a Valid Numerical Value");
            nTextField.setText("");
            return false;
        }
        return true;
    }

    public static void main(String[] args) {
        // TODO code application logic here
        P3GUI foo = new P3GUI();

    }

    /**
     * Controls the action performed when a button is clicked

     */
    @Override
    public void actionPerformed(ActionEvent e) {
        String event = e.getActionCommand();
        String text;
        String result;

        switch (event){

            case "compute":

                text = nTextField.getText();
                if(isNumeric(text) == false) break;

                if(iterativeButton.isSelected()){
                    result = ""+Sequence.computeIterative(Integer.parseInt(text));
                }
                else if(recursiveButton.isSelected()){
                    result = ""+Sequence.computeRecursive(Integer.parseInt(text));
                }
                else{
                    result = "";
                }
                resultTextField.setText(result);
                efficiencyTextField.setText(""+Sequence.getEfficiency());
                break;
        }
    }

    /**
     * Class that defines a windowAdapter to override windowClosing method to perform function on window close
     */
    private static class WindowAdapterImpl extends WindowAdapter {

        public WindowAdapterImpl() {
        }

        @Override
        public void windowClosing(WindowEvent e){
            try {
                int iterativeE;
                int recursiveE;
                FileWriter fw = new FileWriter("Efficiency Values.csv");
                for(int n = 0; n <= 10; n++){
                    Sequence.computeIterative(n);
                    iterativeE = Sequence.getEfficiency();
                    Sequence.computeRecursive(n);
                    recursiveE = Sequence.getEfficiency();
                    fw.write(n+","+iterativeE+","+recursiveE+"\n");
                }
                fw.close();
            } catch (IOException ex) {
                Logger.getLogger(P3GUI.class.getName()).log(Level.SEVERE, null, ex);
            }
        }

    }

}
-------------------------------------------------------------------------------------------
Sequence.java
-------------------------------------------------
public class Sequence {

    private static int efficiency;

    /**Constructor to initialize instance variable
     */
    public Sequence(){
        efficiency = 0;
    }

    /**Computes nth term iteratively, where the nth term is 2 times the previous number plus the next previous number
     */
    public static int computeIterative(int n){

        efficiency = 0;
        int[] s = new int[n+1];

        for(int i = 0; i <= n; i++){
            if(i==0){
                s[i]=0;
            }
            else if(i==1){
                s[i]=1;
            }
            else{
                s[i] = (s[i-1]*2 + s[i-2]);
            }

            efficiency++;
        }

        return s[n];

    }

    /**Helper method for recursive() method
     */
    public static int computeRecursive(int n){
        efficiency = 0;
        return recursive(n);

    }

    /**Computes nth term recursively, where the nth term is 2 times the previous number plus the next previous number
     */
    private static int recursive(int n){
        efficiency++;
        if(n <= 1){
            return n;
        }

        return recursive(n-1)*2+recursive(n-2);

    }

    /**
     * Returns the value of the efficiency counter
     */
    public static int getEfficiency(){
        return efficiency;
    }

}