This from Murach exercise 16-1 on Page 534

Number of Years text field replaced with combobox

Future Value text field replaced with a list having a vertical scrollbar

Calculate button event listener calculates the future values for each year selected in the combobox

Calculate button event listener displays the calculated the future values for each year selected in the list

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These are the Forms gives

murach.business>FinancialCalculations.java

package murach.business;

public class FinancialCalculations { public static final int MONTHS_IN_YEAR = 12;

public static double calculateFutureValue(double monthlyPayment, double yearlyInterestRate, int years) { int months = years * MONTHS_IN_YEAR; double monthlyInterestRate = yearlyInterestRate/MONTHS_IN_YEAR/100; double futureValue = 0; for (int i = 1; i <= months; i++) { futureValue = (futureValue + monthlyPayment) * (1 + monthlyInterestRate); } return futureValue; } }

murach.ui>SwingValidator.java

package murach.ui;

import javax.swing.*; import javax.swing.text.JTextComponent;

public class SwingValidator { public boolean isPresent(JTextComponent c, String fieldName) { if (c.getText().length() == 0) { showMessage(c, fieldName + " is a required field."); c.requestFocusInWindow(); return false; } return true; }

public boolean isInteger(JTextComponent c, String fieldName) { try { int i = Integer.parseInt(c.getText()); return true; } catch (NumberFormatException e) { showMessage(c, fieldName + " must be an integer."); c.requestFocusInWindow(); return false; } }

public boolean isDouble(JTextComponent c, String fieldName) { try { double d = Double.parseDouble(c.getText()); return true; } catch (NumberFormatException e) { showMessage(c, fieldName + " must be a valid number."); c.requestFocusInWindow(); return false; } }

private void showMessage(JTextComponent c, String message) { JOptionPane.showMessageDialog(c, message, "Invalid Entry", JOptionPane.ERROR_MESSAGE); } }

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Thank you.