atharva-0109 / loanassitant.java Goto Github PK

/ *

• LoanAssistant.java
  /
  package loanassistant;
  import javax.swing.;
  import java.awt.;
  import java.awt.event.;
  import java.text.;
  public class LoanAssistant extends JFrame
  {
  JLabel balanceLabel = new JLabel();
  JTextField balanceTextField = new JTextField();
  JLabel interestLabel = new JLabel();
  JTextField interestTextField = new JTextField();
  JLabel monthsLabel = new JLabel();
  JTextField monthsTextField = new JTextField();
  JLabel paymentLabel = new JLabel();
  JTextField paymentTextField = new JTextField();
  JButton computeButton = new JButton();
  JButton newLoanButton = new JButton();
  JButton monthsButton = new JButton();
  JButton paymentButton = new JButton();
  JLabel analysisLabel = new JLabel();
  JTextArea analysisTextArea = new JTextArea();
  JButton exitButton = new JButton();
  Font myFont = new Font("Arial", Font.PLAIN, 16);
  Color lightYellow = new Color(255, 255, 128);
  boolean computePayment;
  public static void main(String args[])
  / Complete Project Code */
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  {
  // create frame
  new LoanAssistant().show();
  }
  public LoanAssistant()
  {
  // frame constructor
  setTitle("Loan Assistant");
  setResizable(false);
  addWindowListener(new WindowAdapter()
  {
  public void windowClosing(WindowEvent evt)
  {
  exitForm(evt);
  }
  });
  getContentPane().setLayout(new GridBagLayout());
  GridBagConstraints gridConstraints;
  balanceLabel.setText("Loan Balance");
  balanceLabel.setFont(myFont);
  gridConstraints = new GridBagConstraints();
  gridConstraints.gridx = 0;
  gridConstraints.gridy = 0;
  gridConstraints.anchor = GridBagConstraints.WEST;
  gridConstraints.insets = new Insets(10, 10, 0, 0);
  getContentPane().add(balanceLabel, gridConstraints);
  balanceTextField.setPreferredSize(new Dimension(100, 25));
  balanceTextField.setHorizontalAlignment(SwingConstants.RIGHT);
  balanceTextField.setFont(myFont);
  gridConstraints = new GridBagConstraints();
  gridConstraints.gridx = 1;
  gridConstraints.gridy = 0;
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  gridConstraints.insets = new Insets(10, 10, 0, 10);
  getContentPane().add(balanceTextField, gridConstraints);
  balanceTextField.addActionListener(new ActionListener ()
  {
  public void actionPerformed(ActionEvent e)
  {
  balanceTextFieldActionPerformed(e);
  }
  });
  interestLabel.setText("Interest Rate");
  interestLabel.setFont(myFont);
  gridConstraints = new GridBagConstraints();
  gridConstraints.gridx = 0;
  gridConstraints.gridy = 1;
  gridConstraints.anchor = GridBagConstraints.WEST;
  gridConstraints.insets = new Insets(10, 10, 0, 0);
  getContentPane().add(interestLabel, gridConstraints);
  interestTextField.setPreferredSize(new Dimension(100, 25));
  interestTextField.setHorizontalAlignment(SwingConstants.RIGHT);
  interestTextField.setFont(myFont);
  gridConstraints = new GridBagConstraints();
  gridConstraints.gridx = 1;
  gridConstraints.gridy = 1;
  gridConstraints.insets = new Insets(10, 10, 0, 10);
  getContentPane().add(interestTextField, gridConstraints);
  interestTextField.addActionListener(new ActionListener ()
  {
  public void actionPerformed(ActionEvent e)
  {
  interestTextFieldActionPerformed(e);
  }
  });
  monthsLabel.setText("Number of Payments");
  monthsLabel.setFont(myFont);
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  gridConstraints = new GridBagConstraints();
  gridConstraints.gridx = 0;
  gridConstraints.gridy = 2;
  gridConstraints.anchor = GridBagConstraints.WEST;
  gridConstraints.insets = new Insets(10, 10, 0, 0);
  getContentPane().add(monthsLabel, gridConstraints);
  monthsTextField.setPreferredSize(new Dimension(100, 25));
  monthsTextField.setHorizontalAlignment(SwingConstants.RIGHT);
  monthsTextField.setFont(myFont);
  gridConstraints = new GridBagConstraints();
  gridConstraints.gridx = 1;
  gridConstraints.gridy = 2;
  gridConstraints.insets = new Insets(10, 10, 0, 10);
  getContentPane().add(monthsTextField, gridConstraints);
  monthsTextField.addActionListener(new ActionListener ()
  {
  public void actionPerformed(ActionEvent e)
  {
  monthsTextFieldActionPerformed(e);
  }
  });
  paymentLabel.setText("Monthly Payment");
  paymentLabel.setFont(myFont);
  gridConstraints = new GridBagConstraints();
  gridConstraints.gridx = 0;
  gridConstraints.gridy = 3;
  gridConstraints.anchor = GridBagConstraints.WEST;
  gridConstraints.insets = new Insets(10, 10, 0, 0);
  getContentPane().add(paymentLabel, gridConstraints);
  paymentTextField.setPreferredSize(new Dimension(100, 25));
  paymentTextField.setHorizontalAlignment(SwingConstants.RIGHT);
  paymentTextField.setFont(myFont);
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  gridConstraints = new GridBagConstraints();
  gridConstraints.gridx = 1;
  gridConstraints.gridy = 3;
  gridConstraints.insets = new Insets(10, 10, 0, 10);
  getContentPane().add(paymentTextField, gridConstraints);
  paymentTextField.addActionListener(new ActionListener ()
  {
  public void actionPerformed(ActionEvent e)
  {
  paymentTextFieldActionPerformed(e);
  }
  });
  computeButton.setText("Compute Monthly Payment");
  gridConstraints = new GridBagConstraints();
  gridConstraints.gridx = 0;
  gridConstraints.gridy = 4;
  gridConstraints.gridwidth = 2;
  gridConstraints.insets = new Insets(10, 0, 0, 0);
  getContentPane().add(computeButton, gridConstraints);
  computeButton.addActionListener(new ActionListener()
  {
  public void actionPerformed(ActionEvent e)
  {
  computeButtonActionPerformed(e);
  }
  });
  newLoanButton.setText("New Loan Analysis");
  newLoanButton.setEnabled(false);
  gridConstraints = new GridBagConstraints();
  gridConstraints.gridx = 0;
  gridConstraints.gridy = 5;
  gridConstraints.gridwidth = 2;
  gridConstraints.insets = new Insets(10, 0, 10, 0);
  getContentPane().add(newLoanButton, gridConstraints);
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  newLoanButton.addActionListener(new ActionListener()
  {
  public void actionPerformed(ActionEvent e)
  {
  newLoanButtonActionPerformed(e);
  }
  });
  monthsButton.setText("X");
  monthsButton.setFocusable(false);
  gridConstraints = new GridBagConstraints();
  gridConstraints.gridx = 2;
  gridConstraints.gridy = 2;
  gridConstraints.insets = new Insets(10, 0, 0, 0);
  getContentPane().add(monthsButton, gridConstraints);
  monthsButton.addActionListener(new ActionListener()
  {
  public void actionPerformed(ActionEvent e)
  {
  monthsButtonActionPerformed(e);
  }
  });
  paymentButton.setText("X");
  paymentButton.setFocusable(false);
  gridConstraints = new GridBagConstraints();
  gridConstraints.gridx = 2;
  gridConstraints.gridy = 3;
  gridConstraints.insets = new Insets(10, 0, 0, 0);
  getContentPane().add(paymentButton, gridConstraints);
  paymentButton.addActionListener(new ActionListener()
  {
  public void actionPerformed(ActionEvent e)
  {
  paymentButtonActionPerformed(e);
  }
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  });
  analysisLabel.setText("Loan Analysis:");
  analysisLabel.setFont(myFont);
  gridConstraints = new GridBagConstraints();
  gridConstraints.gridx = 3;
  gridConstraints.gridy = 0;
  gridConstraints.anchor = GridBagConstraints.WEST;
  gridConstraints.insets = new Insets(0, 10, 0, 0);
  getContentPane().add(analysisLabel, gridConstraints);
  analysisTextArea.setPreferredSize(new Dimension(250, 150));
  analysisTextArea.setFocusable(false);
  analysisTextArea.setBorder(BorderFactory.createLineBorder(Color.BLACK));
  analysisTextArea.setFont(new Font("Courier New", Font.PLAIN, 14));
  analysisTextArea.setEditable(false);
  analysisTextArea.setBackground(Color.WHITE);
  gridConstraints = new GridBagConstraints();
  gridConstraints.gridx = 3;
  gridConstraints.gridy = 1;
  gridConstraints.gridheight = 4;
  gridConstraints.insets = new Insets(0, 10, 0, 10);
  getContentPane().add(analysisTextArea, gridConstraints);
  exitButton.setText("Exit");
  exitButton.setFocusable(false);
  gridConstraints = new GridBagConstraints();
  gridConstraints.gridx = 3;
  gridConstraints.gridy = 5;
  getContentPane().add(exitButton, gridConstraints);
  exitButton.addActionListener(new ActionListener()
  {
  public void actionPerformed(ActionEvent e)
  {
  exitButtonActionPerformed(e);
  }
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  });
  pack();
  Dimension screenSize =
  Toolkit.getDefaultToolkit().getScreenSize();
  setBounds((int) (0.5 * (screenSize.width - getWidth())), (int) (0.5 * (screenSize.height -
  getHeight())), getWidth(), getHeight());
  paymentButton.doClick();
  }
  private void exitForm(WindowEvent evt)
  {
  System.exit(0);
  }
  private void computeButtonActionPerformed(ActionEvent e)
  {
  double balance, interest, payment;
  int months;
  double monthlyInterest, multiplier;
  double loanBalance, finalPayment;
  if (validateDecimalNumber(balanceTextField))
  {
  balance =
  Double.valueOf(balanceTextField.getText()).doubleValue();
  }
  else
  {
  JOptionPane.showConfirmDialog(null, "Invalid or empty Loan Balance entry.\nPlease
  correct.", "Balance Input Error", JOptionPane.DEFAULT_OPTION,
  JOptionPane.INFORMATION_MESSAGE);
  return;
  }
  if (validateDecimalNumber(interestTextField))
  {
  interest =
  Double.valueOf(interestTextField.getText()).doubleValue();
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  }
  else
  {
  JOptionPane.showConfirmDialog(null, "Invalid or empty Interest Rate entry.\nPlease
  correct.", "Interest Input Error", JOptionPane.DEFAULT_OPTION,
  JOptionPane.INFORMATION_MESSAGE);
  return;
  }
  monthlyInterest = interest / 1200;
  if (computePayment)
  {
  // Compute loan payment
  if (validateDecimalNumber(monthsTextField))
  {
  months =
  Integer.valueOf(monthsTextField.getText()).intValue();
  }
  else
  {
  JOptionPane.showConfirmDialog(null, "Invalid or empty Number of Payments
  entry.\nPlease correct.", "Number of Payments Input Error",
  JOptionPane.DEFAULT_OPTION, JOptionPane.INFORMATION_MESSAGE);
  return;
  }
  if (interest == 0)
  {
  payment = balance / months;
  }
  else
  {
  multiplier = Math.pow(1 + monthlyInterest, months);
  payment = balance * monthlyInterest * multiplier / (multiplier - 1);
  }
  paymentTextField.setText(new DecimalFormat("0.00").format(payment));
  }
  else
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  {
  // Compute number of payments
  if (validateDecimalNumber(paymentTextField))
  {
  payment =
  Double.valueOf(paymentTextField.getText()).doubleValue();
  if (payment <= (balance * monthlyInterest + 1.0))
  {
  if (JOptionPane.showConfirmDialog(null, "Minimum payment must be $" +
  new DecimalFormat("0.00").format((int)(balance * monthlyInterest + 1.0)) + "\n" + "Do you
  want to use the minimum payment?", "Input Error", JOptionPane.YES_NO_OPTION,
  JOptionPane.QUESTION_MESSAGE) == JOptionPane.YES_OPTION)
  {
  paymentTextField.setText(new DecimalFormat("0.00").format((int)(balance *
  monthlyInterest + 1.0)));
  payment =
  Double.valueOf(paymentTextField.getText()).doubleValue();
  }
  else
  {
  paymentTextField.requestFocus();
  return;
  }
  }
  }
  else
  {
  JOptionPane.showConfirmDialog(null, "Invalid or empty Monthly Payment
  entry.\nPlease correct.", "Payment Input Error", JOptionPane.DEFAULT_OPTION,
  JOptionPane.INFORMATION_MESSAGE);
  return;
  }
  if (interest == 0)
  {
  months = (int)(balance / payment);
  }
  else
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  {
  months = (int)((Math.log(payment) - Math.log(payment - balance * monthlyInterest)) /
  Math.log(1 + monthlyInterest));
  }
  monthsTextField.setText(String.valueOf(months));
  }
  // reset payment prior to analysis to fix at two decimals
  payment =
  Double.valueOf(paymentTextField.getText()).doubleValue();
  // show analysis
  analysisTextArea.setText("Loan Balance: $" + new
  DecimalFormat("0.00").format(balance));
  analysisTextArea.append("\n" + "Interest Rate: " + new
  DecimalFormat("0.00").format(interest) + "%");
  // process all but last payment
  loanBalance = balance;
  for (int paymentNumber = 1; paymentNumber <= months - 1; paymentNumber++)
  {
  loanBalance += loanBalance * monthlyInterest - payment;
  }
  // find final payment
  finalPayment = loanBalance;
  if (finalPayment > payment)
  {
  // apply one more payment
  loanBalance += loanBalance * monthlyInterest - payment;
  finalPayment = loanBalance;
  months++;
  monthsTextField.setText(String.valueOf(months));
  }
  analysisTextArea.append("\n\n" + String.valueOf(months - 1) + " Payments of $" + new
  DecimalFormat("0.00").format(payment));
  analysisTextArea.append("\n" + "Final Payment of: $" + new
  DecimalFormat("0.00").format(finalPayment));
  analysisTextArea.append("\n" + "Total Payments: $" + new
  DecimalFormat("0.00").format((months - 1) * payment + finalPayment));
  analysisTextArea.append("\n" + "Interest Paid $" + new
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  DecimalFormat("0.00").format((months - 1) * payment + finalPayment - balance));
  computeButton.setEnabled(false);
  newLoanButton.setEnabled(true);
  newLoanButton.requestFocus();
  }
  private void newLoanButtonActionPerformed(ActionEvent e)
  {
  // clear computed value and analysis
  if (computePayment)
  {
  paymentTextField.setText("");
  }
  else
  {
  monthsTextField.setText("");
  }
  analysisTextArea.setText("");
  computeButton.setEnabled(true);
  newLoanButton.setEnabled(false);
  balanceTextField.requestFocus();
  }
  private void monthsButtonActionPerformed(ActionEvent e)
  {
  // will compute months
  computePayment = false;
  paymentButton.setVisible(true);
  monthsButton.setVisible(false);
  monthsTextField.setText("");
  monthsTextField.setEditable(false);
  monthsTextField.setBackground(lightYellow);
  monthsTextField.setFocusable(false);
  paymentTextField.setEditable(true);
  paymentTextField.setBackground(Color.WHITE);
  paymentTextField.setFocusable(true);
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  computeButton.setText("Compute Number of Payments");
  balanceTextField.requestFocus();
  }
  private void paymentButtonActionPerformed(ActionEvent e)
  {
  // will compute payment
  computePayment = true;
  paymentButton.setVisible(false);
  monthsButton.setVisible(true);
  monthsTextField.setEditable(true);
  monthsTextField.setBackground(Color.WHITE);
  monthsTextField.setFocusable(true);
  paymentTextField.setText("");
  paymentTextField.setEditable(false);
  paymentTextField.setBackground(lightYellow);
  paymentTextField.setFocusable(false);
  computeButton.setText("Compute Monthly Payment");
  balanceTextField.requestFocus();
  }
  private void exitButtonActionPerformed(ActionEvent e)
  {
  System.exit(0);
  }
  private void balanceTextFieldActionPerformed(ActionEvent e)
  {
  balanceTextField.transferFocus();
  }
  private void interestTextFieldActionPerformed(ActionEvent e)
  {
  interestTextField.transferFocus();
  }
  private void monthsTextFieldActionPerformed(ActionEvent e)
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  {
  monthsTextField.transferFocus();
  }
  private void paymentTextFieldActionPerformed(ActionEvent e)
  {
  paymentTextField.transferFocus();
  }
  private boolean validateDecimalNumber(JTextField tf)
  {
  // checks to see if text field contains
  // valid decimal number with only digits and a single decimal point
  String s = tf.getText().trim();
  boolean hasDecimal = false;
  boolean valid = true;
  if (s.length() == 0)
  {
  valid = false;
  }
  else
  {
  for (int i = 0; i < s.length(); i++)
  {
  char c = s.charAt(i);
  if (c >= '0' && c <= '9')
  {
  continue;
  }
  else if (c == '.' && !hasDecimal)
  {
  hasDecimal = true;
  }
  else
  {
  // invalid character found
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  valid = false;
  }
  }
  }
  tf.setText(s);
  if (!valid)
  {
  tf.requestFocus();
  }
  return (valid);
  }
  }