/** package EVPIApp; */

import java.awt.*;
import java.awt.event.*;
import java.applet.*;
import com.sun.java.swing.*;
import javax.swing.*;
import java.lang.Float;
import java.lang.Double;


/** Expected Value of Perfect Infromation evpi) applet is to make a
  * decision under risk. In this applet user will be able to enter some
  * values into the textedit fields, after entering the values they will
  * be able to see how the calculations are calculated. If they choose
  * the 'Calculate' button then it will show the result at once, which is
  * the Expected Value of Perfect Information using the best alternative
  * or consequence by chossing their best State of Nature. If they choose
  * the 'Step' button then they will be able to see all the steps of the
  * calculations. There is also a 'Default' button, which will input some
  * default values to the textfield. If the user wish to clear all the
  * area they will be able to do just by clicking ont the 'Clear' button. */


public class evpi extends JApplet {
  boolean isStandalone = false;
  JLabel titleLabel = new JLabel();
  JLabel tableLabel1 = new JLabel();
  JLabel tableLabel2 = new JLabel();
  JLabel tableLabel3 = new JLabel();
  JLabel tableLabel4 = new JLabel();
  JLabel tableLabel5 = new JLabel();
  JLabel tableLabel6 = new JLabel();
  JLabel tableLabel7 = new JLabel();
  JLabel tableLabel8 = new JLabel();
  JLabel tableLabel9 = new JLabel();
  JLabel tableLabel10 = new JLabel();
  JLabel tableLabel11 = new JLabel();
  JLabel tableLabel12 = new JLabel();
  JLabel tableLabel13 = new JLabel();
  JLabel tableLabel14 = new JLabel();
  JLabel tableLabel15 = new JLabel();
  JLabel tableLabel16 = new JLabel();
  JLabel tableLabel17 = new JLabel();
  JLabel tableLabel18 = new JLabel();
  JLabel tableLabel19 = new JLabel();
  JLabel tableLabel110 = new JLabel();
  JTextField favorableLarge = new JTextField();
  JTextField unfavorableLarge = new JTextField();
  JTextField favorableSmall = new JTextField();
  JTextField unfavorableSmall = new JTextField();
  JTextField favorableNothing = new JTextField();
  JTextField unfavorableNothing = new JTextField();
  JTextArea emvComputedLarge = new JTextArea();
  JTextArea emvComputedSmall = new JTextArea();
  JTextArea emvComputedNothing = new JTextArea();
  JTextField favorableProbability = new JTextField();
  JTextField unfavorableProbability = new JTextField();
  JLabel displayAreaLabel = new JLabel();
  JButton defaultButton = new JButton();
  JButton calculateButton = new JButton();
  JButton stepButton = new JButton();
  JButton clearButton = new JButton();
  TextArea displayArea = new TextArea();


  /** variable to step through the applet calculation */
  int step=1;

  /** variables to hold the maximum values of each state */
  double maxFirstState=0.0, maxSecondState = 0.0;

  /** variable to hold the maximum value of the emv */
  double maxProfit = 0.0;

  JLabel tableLabel20 = new JLabel();
  JLabel tableLabel21 = new JLabel();
  JLabel tableLabel111 = new JLabel();
  JTextArea evpiComputed = new JTextArea();
  JPanel jPanel1 = new JPanel();
  JPanel jPanel2 = new JPanel();
  JPanel jPanel3 = new JPanel();
  JPanel jPanel4 = new JPanel();
  JPanel jPanel5 = new JPanel();

  /** Construct the applet  */

  public evpi() {
  }

  /** Initialize the applet */

  public void init() {
    try {
    jbInit();
    }
    catch (Exception e) {
    e.printStackTrace();

    }
  }


  /** Component initialization, GUI of the evpi applet */

  private void jbInit() throws Exception {
    titleLabel.setText("Expected Value of Perfect Information");
    titleLabel.setForeground(Color.blue);
    titleLabel.setFont(new Font("Dialog", 1, 20));
    titleLabel.setBounds(new Rectangle(142, 9, 362, 37));
    tableLabel1.setText("Decision Table with Probabilities, EMVs, and EVPI");
    tableLabel1.setBackground(Color.red);
    tableLabel1.setFont(new Font("Dialog", 1, 14));
    tableLabel1.setBounds(new Rectangle(9, 5, 350, 26));
    tableLabel2.setFont(new Font("Dialog", 0, 14));
    tableLabel2.setBackground(Color.red);
    tableLabel2.setText("STATE OF NATURE");
    tableLabel2.setBounds(new Rectangle(226, 82, 140, 26));
    tableLabel3.setFont(new Font("Dialog", 0, 14));
    tableLabel3.setBackground(Color.red);
    tableLabel3.setText("ALTERNATIVE");
    tableLabel3.setBounds(new Rectangle(19, 139, 99, 26));
    tableLabel4.setBounds(new Rectangle(185, 105, 89, 26));
    tableLabel5.setBounds(new Rectangle(304, 105, 110, 26));
    tableLabel6.setBounds(new Rectangle(456, 105, 36, 26));
    tableLabel7.setBounds(new Rectangle(196, 123, 60, 26));
    tableLabel8.setBounds(new Rectangle(324, 122, 61, 26));
    tableLabel9.setBounds(new Rectangle(431, 121, 85, 26));
    tableLabel10.setBounds(new Rectangle(215, 138, 21, 26));
    tableLabel11.setBounds(new Rectangle(342, 138, 21, 26));
    tableLabel12.setBounds(new Rectangle(460, 137, 21, 26));
    tableLabel13.setBounds(new Rectangle(182, 89, 247, 18));
    tableLabel14.setBounds(new Rectangle(8, 142, 651, 26));
    tableLabel15.setBounds(new Rectangle(10, 6, 151, 26));
    tableLabel16.setFont(new Font("Dialog", 1, 13));
    tableLabel16.setBackground(Color.red);
    tableLabel16.setText("Construct a small plant");
    tableLabel16.setBounds(new Rectangle(7, 8, 154, 26));
    tableLabel17.setBounds(new Rectangle(7, 7, 136, 26));
    tableLabel18.setFont(new Font("Dialog", 0, 14));
    tableLabel18.setBackground(Color.red);
    tableLabel18.setText("_______________________________________________________________________________");
    tableLabel18.setBounds(new Rectangle(8, 257, 643, 26));
    tableLabel19.setFont(new Font("Dialog", 1, 13));
    tableLabel19.setBackground(Color.red);
    tableLabel19.setText("Probabilities");
    tableLabel19.setBounds(new Rectangle(8, 8, 89, 26));
    tableLabel110.setBounds(new Rectangle(8, 296, 641, 26));
    favorableLarge.setBounds(new Rectangle(168, 4, 99, 29));
    unfavorableLarge.setBounds(new Rectangle(295, 4, 99, 29));
    favorableSmall.setBounds(new Rectangle(169, 4, 99, 29));
    unfavorableSmall.setBounds(new Rectangle(296, 4, 99, 29));
    favorableNothing.setBounds(new Rectangle(168, 5, 99, 29));
    unfavorableNothing.setBounds(new Rectangle(296, 5, 99, 29));
    emvComputedLarge.setDisabledTextColor(Color.black);
    emvComputedLarge.setBounds(new Rectangle(413, 4, 100, 29));
    emvComputedSmall.setDisabledTextColor(Color.black);
    emvComputedSmall.setBounds(new Rectangle(413, 4, 100, 29));
    emvComputedNothing.setDisabledTextColor(Color.black);
    emvComputedNothing.setBounds(new Rectangle(413, 5, 100, 29));
    favorableProbability.setBounds(new Rectangle(169, 4, 99, 29));
    unfavorableProbability.setBounds(new Rectangle(296, 5, 99, 29));
    displayAreaLabel.setText("Display Area");
    displayAreaLabel.setForeground(Color.red);
    displayAreaLabel.setFont(new Font("Dialog", 0, 16));
    displayAreaLabel.setBounds(new Rectangle(278, 323, 94, 28));

    /** set up for the default button */
    defaultButton.setText("Default");
    defaultButton.setFont(new Font("Dialog", 1, 12));
    defaultButton.setBounds(new Rectangle(130, 540, 91, 37));
    defaultButton.addActionListener(new java.awt.event.ActionListener() {

      /** action performed for the default button. */
      public void actionPerformed(ActionEvent e) {
        defaultButton_actionPerformed(e);
      }
    });

    /** set up for the calculate button */
    calculateButton.setFont(new Font("Dialog", 1, 12));
    calculateButton.setText("Calculate");
    calculateButton.setBounds(new Rectangle(230, 540, 91, 37));
    calculateButton.addActionListener(new java.awt.event.ActionListener() {

     /** action performed for the calculate button. */
      public void actionPerformed(ActionEvent e) {
        calculateButton_actionPerformed(e);
      }
    });

    /** set up for the step button */
    stepButton.setFont(new Font("Dialog", 1, 12));
    stepButton.setText("Step");
    stepButton.setBounds(new Rectangle(329, 540, 91, 37));
    stepButton.addActionListener(new java.awt.event.ActionListener() {

     /** action performed for the step button. */
      public void actionPerformed(ActionEvent e) {
        stepButton_actionPerformed(e);
      }
    });

    /** set up for the clear button */
    clearButton.setFont(new Font("Dialog", 1, 12));
    clearButton.setText("Clear");
    clearButton.setBounds(new Rectangle(428, 540, 91, 37));
    clearButton.addActionListener(new java.awt.event.ActionListener() {

     /** action performed for the clear button. */
      public void actionPerformed(ActionEvent e) {
        clearButton_actionPerformed(e);
      }
    });

    /** set up for the display area */
    displayArea.setBackground(Color.white);
    displayArea.setBounds(new Rectangle(82, 353, 483, 177));

    /** set up for the table label */
    tableLabel20.setBounds(new Rectangle(567, 105, 36, 26));
    tableLabel21.setBounds(new Rectangle(542, 121, 85, 26));
    tableLabel111.setBounds(new Rectangle(572, 137, 21, 26));
    evpiComputed.setDisabledTextColor(Color.black);
    evpiComputed.setBounds(new Rectangle(524, 4, 100, 29));
    jPanel1.setLayout(null);
    jPanel1.setBackground(new Color(46, 170, 178));
    jPanel1.setBounds(new Rectangle(8, 47, 633, 38));
    jPanel2.setLayout(null);
    jPanel2.setBackground(new Color(46, 170, 178));
    jPanel2.setBounds(new Rectangle(8, 163, 633, 38));
    jPanel3.setLayout(null);
    jPanel3.setBackground(new Color(46, 170, 178));
    jPanel3.setBounds(new Rectangle(8, 239, 633, 38));
    jPanel4.setBounds(new Rectangle(8, 201, 633, 38));
    jPanel5.setLayout(null);
    jPanel5.setBackground(new Color(85, 201, 255));
    jPanel5.setBounds(new Rectangle(8, 278, 633, 38));
    jPanel4.setBackground(new Color(85, 201, 255));
    jPanel4.setLayout(null);
    tableLabel111.setText("($)");
    tableLabel111.setBackground(Color.red);
    tableLabel111.setFont(new Font("Dialog", 0, 14));
    tableLabel21.setText("COMPUTED");
    tableLabel21.setBackground(Color.red);
    tableLabel21.setFont(new Font("Dialog", 0, 14));
    tableLabel20.setText("EVPI");
    tableLabel20.setBackground(Color.red);
    tableLabel20.setFont(new Font("Dialog", 0, 14));
    tableLabel110.setText("_______________________________________________________________________________");
    tableLabel110.setBackground(Color.red);
    tableLabel110.setFont(new Font("Dialog", 0, 14));
    tableLabel17.setText("Construct nothing");
    tableLabel17.setBackground(Color.red);
    tableLabel17.setFont(new Font("Dialog", 1, 13));
    tableLabel15.setText("Construct a large plant");
    tableLabel15.setBackground(Color.red);
    tableLabel15.setFont(new Font("Dialog", 1, 13));
    tableLabel14.setText("_______________________________________________________________________________");
    tableLabel14.setBackground(Color.red);
    tableLabel14.setFont(new Font("Dialog", 0, 14));
    tableLabel13.setText("____________________________");
    tableLabel13.setBackground(Color.red);
    tableLabel13.setFont(new Font("Dialog", 0, 14));
    tableLabel12.setText("($)");
    tableLabel12.setBackground(Color.red);
    tableLabel12.setFont(new Font("Dialog", 0, 14));
    tableLabel11.setText("($)");
    tableLabel11.setBackground(Color.red);
    tableLabel11.setFont(new Font("Dialog", 0, 14));
    tableLabel10.setText("($)");
    tableLabel10.setBackground(Color.red);
    tableLabel10.setFont(new Font("Dialog", 0, 14));
    tableLabel9.setText("COMPUTED");
    tableLabel9.setBackground(Color.red);
    tableLabel9.setFont(new Font("Dialog", 0, 14));
    tableLabel8.setText("MARKET");
    tableLabel8.setBackground(Color.red);
    tableLabel8.setFont(new Font("Dialog", 0, 14));
    tableLabel7.setText("MARKET");
    tableLabel7.setBackground(Color.red);
    tableLabel7.setFont(new Font("Dialog", 0, 14));
    tableLabel6.setText("EMV");
    tableLabel6.setBackground(Color.red);
    tableLabel6.setFont(new Font("Dialog", 0, 14));
    tableLabel5.setText("UNFAVORABLE");
    tableLabel5.setBackground(Color.red);
    tableLabel5.setFont(new Font("Dialog", 0, 14));
    tableLabel4.setText("FAVORABLE");
    tableLabel4.setBackground(Color.red);
    tableLabel4.setFont(new Font("Dialog", 0, 14));
    this.getContentPane().setLayout(null);
    this.setSize(644,648);
    this.getContentPane().add(titleLabel, null);
    this.getContentPane().add(tableLabel20, null);
    this.getContentPane().add(tableLabel6, null);
    this.getContentPane().add(tableLabel5, null);
    this.getContentPane().add(tableLabel4, null);
    this.getContentPane().add(tableLabel111, null);
    this.getContentPane().add(tableLabel12, null);
    this.getContentPane().add(tableLabel11, null);
    this.getContentPane().add(tableLabel10, null);
    this.getContentPane().add(tableLabel21, null);
    this.getContentPane().add(tableLabel9, null);
    this.getContentPane().add(tableLabel8, null);
    this.getContentPane().add(tableLabel7, null);
    this.getContentPane().add(tableLabel13, null);
    this.getContentPane().add(tableLabel110, null);
    this.getContentPane().add(tableLabel18, null);
    this.getContentPane().add(tableLabel14, null);
    this.getContentPane().add(tableLabel3, null);
    this.getContentPane().add(tableLabel2, null);
    this.getContentPane().add(displayAreaLabel, null);
    this.getContentPane().add(clearButton, null);
    this.getContentPane().add(stepButton, null);
    this.getContentPane().add(calculateButton, null);
    this.getContentPane().add(defaultButton, null);
    this.getContentPane().add(displayArea, null);
    this.getContentPane().add(jPanel1, null);
    jPanel1.add(tableLabel1, null);
    this.getContentPane().add(jPanel3, null);
    jPanel3.add(tableLabel17, null);
    jPanel3.add(favorableNothing, null);
    jPanel3.add(unfavorableNothing, null);
    jPanel3.add(emvComputedNothing, null);
    this.getContentPane().add(jPanel4, null);
    jPanel4.add(tableLabel16, null);
    jPanel4.add(favorableSmall, null);
    jPanel4.add(unfavorableSmall, null);
    jPanel4.add(emvComputedSmall, null);
    this.getContentPane().add(jPanel2, null);
    jPanel2.add(tableLabel15, null);
    jPanel2.add(favorableLarge, null);
    jPanel2.add(evpiComputed, null);
    jPanel2.add(unfavorableLarge, null);
    jPanel2.add(emvComputedLarge, null);
    this.getContentPane().add(jPanel5, null);
    jPanel5.add(tableLabel19, null);
    jPanel5.add(favorableProbability, null);
    jPanel5.add(unfavorableProbability, null);
  }

  /** Get Applet information */

  public String getAppletInfo() {
    return "Applet Information";
  }

  /** Get parameter info */

  public String[][] getParameterInfo() {
    return null;
  }

 
   /** clearButton_actionPerformed method is to clear all the textfield
     * and display area. This will also set the background of all the
     * textfield and display area back to white. */

  void clearButton_actionPerformed(ActionEvent e) {
    displayArea.setText("");
    favorableLarge.setText("");
    favorableSmall.setText("");
    emvComputedLarge.setText("");
    unfavorableLarge.setText("");
    unfavorableSmall.setText("");
    emvComputedSmall.setText("");
    favorableNothing.setText("");
    unfavorableNothing.setText("");
    emvComputedNothing.setText("");
    favorableProbability.setText("");
    unfavorableProbability.setText("");
    displayArea.setText("");
    favorableLarge.setBackground(Color.white);
    favorableSmall.setBackground(Color.white);
    favorableNothing.setBackground(Color.white);
    unfavorableLarge.setBackground(Color.white);
    unfavorableSmall.setBackground(Color.white);
    unfavorableNothing.setBackground(Color.white);
    emvComputedLarge.setBackground(Color.white);
    emvComputedSmall.setBackground(Color.white);
    emvComputedNothing.setBackground(Color.white);
    evpiComputed.setText("");
    evpiComputed.setBackground(Color.white);
    step=1;
  }

  /** defaultButton_actionPerformed method is to input all the default
    * values into the textfield. This will also set the background of
    * all the textfield into white. */

  void defaultButton_actionPerformed(ActionEvent e) {
    displayArea.setText("");
    favorableLarge.setText("200000");
    favorableSmall.setText("100000");
    unfavorableLarge.setText("-180000");
    unfavorableSmall.setText("-20000");
    favorableNothing.setText("0");
    unfavorableNothing.setText("0");
    favorableProbability.setText("0.5");
    unfavorableProbability.setText("0.5");
    favorableLarge.setBackground(Color.white);
    favorableSmall.setBackground(Color.white);
    favorableNothing.setBackground(Color.white);
    unfavorableLarge.setBackground(Color.white);
    unfavorableSmall.setBackground(Color.white);
    unfavorableNothing.setBackground(Color.white);
    emvComputedLarge.setBackground(Color.white);
    emvComputedSmall.setBackground(Color.white);
    emvComputedNothing.setBackground(Color.white);
    emvComputedLarge.setText("");
    emvComputedSmall.setText("");
    emvComputedNothing.setText("");
    evpiComputed.setText("");
    evpiComputed.setBackground(Color.white);
    step=1;
  }

  /** calculateButton_actionPerformed method is to performed the
    * calculation of the Expected Value of Perfect Information applet.
    * This method takes the default values, which is already been set up
    * or the user input and then calculates all the necessary calculation
    * to get the alternative that gives the best result of perfect information
    * or consequence for every alternative. If no default values thenit takes
    * an user input and does the calculation for the evpi calculation as necessary.
    * To calculate the evpi, at first it calculates the emv for each alternatives.
    * It also set the background color of the emv outcome in green. Similarly, it
    * Then, it calculates the best outcomes from the favorable and unfavorable markets
    * set the background color to orange. After calculating the best alternatives, it
    * will calculate the highest emv and set the background color to orange. Finally,
    * it calculates the evpi using the best alternatives in a favorable market, an
    * unfavorable market and the highest emv computed. After, it will highlight the
    * result in green color. Which is the evpi value, by this value user will be able
    * to make a decision under risk. */

  void calculateButton_actionPerformed(ActionEvent e) {

    /** declaration of all the variables that have been used in the calculation_actionPerformed
      * method. */

    /** variables to hold all the values of the alternatives in each state of nature */
    double favLarge=0.0, favSmall=0.0, favNothing=0.0, unfavLarge=0.0, unfavSmall=0.0, unfavNothing=0.0;

    /** variables to hold the values for the probability of each state of nature */
    double favProbability=0.0, unfavProbability=0.0;

    /** variables to hold the values of the emv computed */
    double emvCompLarge=0.0, emvCompSmall=0.0, emvCompNothing=0.0;

    /** variable to hold the maximum emv computed*/
    double maxProfit=0.0;

    /** variable to hold the evpi of perfect information computed*/
    double evpiComp=0.0;

   /** variable to hold the evpi with perfect information computed*/
    double evpiCompInfo=0.0;

    /** variables to hold the maximum of each state of nature */
    double maxFirstState=0.0, maxSecondState=0.0;

    try {
      displayArea.setText("");
      favLarge = Double.parseDouble(favorableLarge.getText());
      favSmall = Double.parseDouble(favorableSmall.getText());
      favNothing = Double.parseDouble(favorableNothing.getText());
      unfavLarge = Double.parseDouble(unfavorableLarge.getText());
      unfavSmall = Double.parseDouble(unfavorableSmall.getText());
      unfavNothing = Double.parseDouble(unfavorableNothing.getText());
      favProbability = Double.parseDouble(favorableProbability.getText());
      unfavProbability = Double.parseDouble(unfavorableProbability.getText());


     if(favProbability<0||favProbability>1||unfavProbability<0||unfavProbability>1) {

      displayArea.appendText("Your values for probability must be between 0 and 1.\n");
     }

    else {
    /** calculating the emv for the alternatives. */
    emvCompLarge = ((favProbability)*(favLarge)+(unfavProbability)*(unfavLarge));
    emvCompSmall = ((favProbability)*(favSmall)+(unfavProbability)*(unfavSmall));
    emvCompNothing = ((favProbability)*(favNothing)+(unfavProbability)*(unfavNothing));

    /** setting the emv values into the table. */
    emvComputedLarge.setText(""+emvCompLarge);
    emvComputedSmall.setText(""+emvCompSmall);
    emvComputedNothing.setText(""+emvCompNothing);


    /** disabling the textfield for the emv that have been just calculated. */
    emvComputedLarge.disable();
    emvComputedSmall.disable();
    emvComputedNothing.disable();


    /** calculating the maximum emv. */
    if ((emvCompLarge>=emvCompSmall)&(emvCompLarge>=emvCompNothing)) {
      maxProfit = emvCompLarge;
      emvComputedLarge.setBackground(Color.orange);
    }
    else
      emvComputedLarge.setBackground(Color.white);


    if ((emvCompSmall>=emvCompLarge)&(emvCompSmall>=emvCompNothing)) {
      maxProfit = emvCompSmall;
      emvComputedSmall.setBackground(Color.orange);
    }
    else
      emvComputedSmall.setBackground(Color.white);


    if ((emvCompNothing>=emvCompLarge)&(emvCompNothing>=emvCompSmall)) {
      maxProfit = emvCompNothing;
      emvComputedNothing.setBackground(Color.orange);
    }
    else
      emvComputedNothing.setBackground(Color.white);

    /** calculating the best alternative from the favorable market. */
    if ((favLarge>=favSmall)&(favLarge>=favNothing)){
      maxFirstState=favLarge;
      favorableLarge.setBackground(Color.orange);
    }
    else
      favorableLarge.setBackground(Color.white);

    if ((favSmall>=favLarge)&(favSmall>=favNothing)){
      maxFirstState=favSmall;
      favorableSmall.setBackground(Color.orange);
    }
    else
      favorableSmall.setBackground(Color.white);

    if ((favNothing>=favLarge)&(favNothing>=favSmall)){
      maxFirstState=favNothing;
      favorableNothing.setBackground(Color.orange);
    }
    else
      favorableNothing.setBackground(Color.white);

    /** calculating the best alternative from the unfavorable market. */
    if ((unfavLarge>=unfavSmall)&(unfavLarge>=unfavNothing)){
      maxSecondState=unfavLarge;
      unfavorableLarge.setBackground(Color.orange);
    }
    else
      unfavorableLarge.setBackground(Color.white);

    if ((unfavSmall>=unfavLarge)&(unfavSmall>=unfavNothing)){
      maxSecondState=unfavSmall;
      unfavorableSmall.setBackground(Color.orange);
    }
    else
      unfavorableSmall.setBackground(Color.white);

    if ((unfavNothing>=unfavLarge)&(unfavNothing>=unfavSmall)){
      maxSecondState=unfavNothing;
      unfavorableNothing.setBackground(Color.orange);
    }
    else
      unfavorableNothing.setBackground(Color.white);

    /** calculating the expected value with perfect information. */
    evpiCompInfo = ((maxFirstState*favProbability)+(maxSecondState*unfavProbability));

    /** calculating the expected value of perfect information.*/
    evpiComp = evpiCompInfo - maxProfit;

    /** inserting the evpi value to the result area. */
    evpiComputed.setText(""+evpiComp);
    evpiComputed.setBackground(Color.green);
    evpiComputed.disable();

    /** displaying all the calculations into the display area. */
    displayArea.append("EMV(large plant) = ("+favProbability+")($"+favLarge+
                      ") + ("+unfavProbability+")($"+unfavLarge+") = $"+emvCompLarge+"\n");
    displayArea.append("EMV(small plant) = ("+favProbability+")($"+favSmall+
                      ") + ("+unfavProbability+")($"+unfavSmall+") = $"+emvCompSmall+"\n");
    displayArea.append("EMV(construct nothing) = ("+favProbability+")($"+favNothing+
                      ") + ("+unfavProbability+")($"+unfavNothing+") = $"+emvCompNothing+"\n\n");
    displayArea.append("The maximum of the favorable market is $" +maxFirstState+".\n");
    displayArea.append("The maximum of the unfavorable market is $" +maxSecondState+".\n");
    displayArea.append("The maximum of the EMV computed is $" +maxProfit+".\n");
    displayArea.append("EVPI = ($"+maxFirstState+")("+favProbability+")+($"+maxSecondState+")("+unfavProbability+")-"+maxProfit+"\n");
    displayArea.append("EVPI = $"+evpiComp+"\n\n");

    step=1; /** back to step 1 */
   } /** end of else */
  } /** end of try */

   /**  try to catch the exception of invalid inputs */
    catch (Exception r) {
      displayArea.append("Sorry!  One of the values you have entered may not be valid.\n");
      displayArea.append("Please check your values and re-enter any incorrect ones (non-digit).\n");
      displayArea.append("You must also have values entered in all textfields for the \n");
      displayArea.append("State of Nature, favorable and unfavorable markets. \n\n");
    } /** end of catch */

 }//end method


   /** stepButton_actionPerformed method is to performed the calculation of the
    * evpi applet when the 'Step' button has been click on. In each step it will
    * calculate one of the calculation of the evpi applet. To step through the
    * applet, user must input the default values or input some values into the
    * textfield, otherwise they will not be able to step through at all. At the
    * first step it will calculate the emv for constructing a large plant. It will
    * show all the calculation into the display area at the same time for user to
    * go through the calculation. It will also highlight the emv textfield to green color.
    * Similarlly, it will calculate the second and third steps and set the textfield to
    * green color. At the fourth step it will calculate the best alternative in a favorable
    * market. This calculation has also been shown into the display area at the same time for
    * user to go through. It will also highlight the textfield to orange color.
    * Similarly, in the next steps it will also calculte the best alternative for the unfavorable
    * market at the same time it will display them into the display area and set the textfield to
    * orange color. In the step six, it will calculate the alternatives with the highest emv, at
    * the same time dispaly it into the display area and highlight it to orange color.
    * At the final step it will calculate the evpi with perfect information and evpi of perfect
    * information. User will be able to see the calculation in the display area. It will highlight
    * the textfield to green color. If user wish to go through the step once more with the same
    * inputs, they can do that by keep clicking on the 'Step' button. */

  void stepButton_actionPerformed(ActionEvent e) {

    /** declaration of all the variables that have been used in the calculation_actionPerformed
      * method. */

    /** variables to hold all the values of the alternatives in each state of nature */
    double favLarge=0.0, favSmall=0.0, favNothing=0.0, unfavLarge=0.0, unfavSmall=0.0, unfavNothing=0.0;

    /** variables to hold the values for the probability of each state of nature */
    double favProbability=0.0, unfavProbability=0.0;

    /** variables to hold the values of the emv computed */
    double emvCompLarge=0.0, emvCompSmall=0.0, emvCompNothing=0.0;

    /** variable to hold the evpi of perfect information computed*/
    double evpiComp=0.0;

   /** variable to hold the evpi with perfect information computed*/
    double evpiCompInfo=0.0;

    try {
      favLarge = Double.parseDouble(favorableLarge.getText());
      favSmall = Double.parseDouble(favorableSmall.getText());
      favNothing = Double.parseDouble(favorableNothing.getText());
      unfavLarge = Double.parseDouble(unfavorableLarge.getText());
      unfavSmall = Double.parseDouble(unfavorableSmall.getText());
      unfavNothing = Double.parseDouble(unfavorableNothing.getText());
      favProbability = Double.parseDouble(favorableProbability.getText());
      unfavProbability = Double.parseDouble(unfavorableProbability.getText());


    /** calculation of the emv */
    emvCompLarge = ((favProbability)*(favLarge)+(unfavProbability)*(unfavLarge));
    emvCompSmall = ((favProbability)*(favSmall)+(unfavProbability)*(unfavSmall));
    emvCompNothing = ((favProbability)*(favNothing)+(unfavProbability)*(unfavNothing));


    /** Step 1 is to find the emv for constructing a large plant. */
    if (step==1){
     displayArea.setText("");
     if(favProbability<0||favProbability>1||unfavProbability<0||unfavProbability>1) {
        displayArea.appendText("Your values for probability must be between 0 and 1.\n");
     }
     else {
      emvComputedLarge.setBackground(Color.white);
      emvComputedSmall.setBackground(Color.white);
      emvComputedNothing.setBackground(Color.white);
      evpiComputed.setBackground(Color.white);
      favorableLarge.setBackground(Color.white);
      favorableSmall.setBackground(Color.white);
      favorableNothing.setBackground(Color.white);
      unfavorableLarge.setBackground(Color.white);
      unfavorableSmall.setBackground(Color.white);
      unfavorableNothing.setBackground(Color.white);
      emvComputedLarge.setText("");
      emvComputedSmall.setText("");
      emvComputedNothing.setText("");
      evpiComputed.setText("");
      emvComputedLarge.setText(""+emvCompLarge);
      emvComputedLarge.setBackground(Color.green);
      emvComputedLarge.disable();

      /** displaying the calculation into the display area. */
      displayArea.append("The first step is to calculate the Expected Monetary Value for the large plant.\n");
      displayArea.append("EMV(large plant) = ("+favProbability+")($"+favLarge+
                      ") + ("+unfavProbability+")($"+unfavLarge+") = $"+emvCompLarge+"\n\n");
      displayArea.append("Click the 'Step' button again.\n\n");
      step=2;
    } }

    /** Step 2 is to find the emv for constructing a small plant. */
    else if(step==2){
      displayArea.setText("");
      emvComputedSmall.setText(""+emvCompSmall);
      emvComputedLarge.setBackground(Color.white);
      emvComputedSmall.setBackground(Color.green);
      emvComputedSmall.disable();


      /** displaying the calculation into the display area. */
      displayArea.append("The second step is to calculate the Expected Monetary Value for the small plant.\n");
      displayArea.append("EMV(small plant) = ("+favProbability+")($"+favSmall+
                      ") + ("+unfavProbability+")($"+unfavSmall+") = $"+emvCompSmall+"\n\n");
      displayArea.append("Click the 'Step' button again.\n\n");
      step=3;
    }

    /** Step 3 is to find the emv for constructing nothing. */
    else if(step==3){
      displayArea.setText("");
      emvComputedNothing.setText(""+emvCompNothing);
      emvComputedSmall.setBackground(Color.white);
      emvComputedNothing.setBackground(Color.green);
      emvComputedNothing.disable();

      /** displaying the calculation into the display area */
      displayArea.append("The third step is to calculate the Expected Monetary Value for constructing nothing.\n");
      displayArea.append("EMV(construct nothing) = ("+favProbability+")($"+favNothing+
                      ") + ("+unfavProbability+")($"+unfavNothing+") = $"+emvCompNothing+"\n\n");
      displayArea.append("Click the 'Step' button again.\n\n");
      step=4;
    }

    /** Step 4 is to find the best alternative from the favorable market. */
    else if(step==4){
      displayArea.setText("");
      emvComputedLarge.setBackground(Color.white);
      emvComputedSmall.setBackground(Color.white);
      emvComputedNothing.setBackground(Color.white);

      displayArea.append("Find the best alternative from the favorable market.\n");

      if ((favLarge>=favSmall)&(favLarge>=favNothing)){
        maxFirstState=favLarge;
        favorableLarge.setBackground(Color.orange);
      }
      else
        favorableLarge.setBackground(Color.white);

      if ((favSmall>=favLarge)&(favSmall>=favNothing)){
        maxFirstState=favSmall;
        favorableSmall.setBackground(Color.orange);
      }
      else
        favorableSmall.setBackground(Color.white);

      if ((favNothing>=favLarge)&(favNothing>=favSmall)){
        maxFirstState=favNothing;
        favorableNothing.setBackground(Color.orange);
      }
      else
        favorableNothing.setBackground(Color.white);

      /** displaying the calculation into the display area. */
      displayArea.append("Maximum of Favorable Market = $"+maxFirstState+"\n\n");
      displayArea.append("Click the 'Step' button again.\n\n");

      step=5;
    }

    /** Step 5 is to find the best alternative from the unfavorable market. */
    else if(step==5){
      displayArea.setText("");
      displayArea.append("Find the best alternative from the unfavorable market.\n");

      if ((unfavLarge>=unfavSmall)&(unfavLarge>=unfavNothing)){
        maxSecondState=unfavLarge;
        unfavorableLarge.setBackground(Color.orange);
      }
      else
        unfavorableLarge.setBackground(Color.white);

      if ((unfavSmall>=unfavLarge)&(unfavSmall>=unfavNothing)){
        maxSecondState=unfavSmall;
        unfavorableSmall.setBackground(Color.orange);
      }
      else
        unfavorableSmall.setBackground(Color.white);

      if ((unfavNothing>=unfavLarge)&(unfavNothing>=unfavSmall)){
        maxSecondState=unfavNothing;
        unfavorableNothing.setBackground(Color.orange);
      }
      else
        unfavorableNothing.setBackground(Color.white);

      /** displaying the calculation into the display area. */
      displayArea.append("Maximum of Unfavorable Market = $"+maxSecondState+"\n\n");
      displayArea.append("Click the 'Step' button again.\n\n");

      step=6;
    }

    /** Step 6 is to find the alternative with the highest emv. */
    else if(step==6){
      displayArea.setText("");
      displayArea.append("Find the alternative with the highest Expected Monetary Value.\n");

      if ((emvCompLarge>=emvCompSmall)&(emvCompLarge>=emvCompNothing)) {
        maxProfit = emvCompLarge;
        emvComputedLarge.setBackground(Color.orange);
      }
      else
        emvComputedLarge.setBackground(Color.white);

      if ((emvCompSmall>=emvCompLarge)&(emvCompSmall>=emvCompNothing)) {
        maxProfit = emvCompSmall;
        emvComputedSmall.setBackground(Color.orange);
      }
      else
        emvComputedSmall.setBackground(Color.white);

      if ((emvCompNothing>=emvCompLarge)&(emvCompNothing>=emvCompSmall)) {
        maxProfit = emvCompNothing;
        emvComputedNothing.setBackground(Color.orange);
      }
      else
        emvComputedNothing.setBackground(Color.white);

      /** displaying the calculation into the display area. */
      displayArea.append("The highest Expected Monetary Value = $"+maxProfit+"\n\n");
      displayArea.append("Click the 'Step' button again.\n\n");

      step=7;
    } /** end elseif */

    /** Step 7 is to find the evpi using the best alternative in a favorable
      * market, an unfavorable market and the highest emv computed. */

    else if(step==7){
      displayArea.setText("");
      evpiCompInfo = ((maxFirstState*favProbability)+(maxSecondState*unfavProbability));
      evpiComp = evpiCompInfo - maxProfit;

      /** displaying the calculation into the display area. */
      displayArea.append("Calculate the EVPI using the best alternative in a favorable market,\n");
      displayArea.append("an unfavorable market, and the highest EMV computed.\n");
      displayArea.append("The maximum of the EMV computed is $" +maxProfit+".\n");
      displayArea.append("EVPI = ($"+maxFirstState+")("+favProbability+")+($"+maxSecondState+")("+unfavProbability+")-"+maxProfit+"\n");
      displayArea.append("EVPI = $"+evpiComp+"\n\n");

      /** setting the evpi into the result area.*/
      evpiComputed.setText(""+evpiComp);
      evpiComputed.setBackground(Color.green);
      evpiComputed.disable();

      step=1;  /** back to step 1 */
    } /** end elseif */

   } /** end of try */

    /**  try to catch the exception of invalid inputs */
    catch (Exception r) {
      displayArea.append("Sorry!  One of the values you have entered may not be valid.\n");
      displayArea.append("Please check your values and re-enter any incorrect ones (non-digit).\n");
      displayArea.append("You must also have values entered in all textfields for the \n");
      displayArea.append("State of Nature, favorable and unfavorable markets. \n\n");
    } /** end of catch */

   } /** end method */

} /** end class */