Mortgage calculator with GUI- Clear button not working

You are not initialzing "loanField" variable.

>                loanField.setText(null);
>                termField.setText(null);
>                rateField.setText(null);
>                paymentField.setText(null);
try changing this to:

            p.setText(null);
            t.setText(null);
            r.setText(null);
            m.setText(null);

the function mortCal() should also be changed as:


    public void mortCal() {
        if (p.getText().trim().length() == 0 || r.getText().trim().length() == 0 || t.getText().trim().length() == 0) {
            paymentLabel.setText("Payment:");
            return;
        }

        double principle = Double.parseDouble(p.getText());
        double rate = Double.parseDouble(r.getText());
        double term = Double.parseDouble(t.getText());
        double interest = (rate / 100 / 12);
        double payment = (principle * interest) / (1 - Math.pow(1 / (1 + interest), term * 12));
        displayPayment.setText("" + NumberFormat.getCurrencyInstance(Locale.US).format(payment));
    }

In my last comment,
> paymentLabel.setText("Payment:");
should be:
displayPayment.setText(null);

>>The mortcal() need no te changed
mortcalc() need not be changed

Thanks. It compiled without errors, but now the Calculate button is not working. This the program with your suggested changes.

import javax.swing.*;
   import java.awt.*;
   import java.awt.event.*;
   import java.io.*;
   import java.text.DecimalFormat;
   import javax.swing.JTextField.*;

   import java.text.NumberFormat;

    public class MortgagePay extends JFrame implements ActionListener
   {
         private static String default_loan = null;
         private static String default_term = null;
         private static String default_rate = null;
         private static String default_payment = null;



      //setup format for currency
          DecimalFormat money = new DecimalFormat("$###,###.00");


          //Declare output stream
          DataOutputStream output;

          //Construct a panel for each row
          private JPanel firstRow = new JPanel();
          private JPanel secondRow = new JPanel();
          private JPanel thirdRow = new JPanel();
          private JPanel fourthRow = new JPanel();

          //Construct a panel for the fields and buttons
          JPanel fieldPanel = new JPanel();
          JPanel buttonPanel = new JPanel();

          private JTextField loanField;
          private JTextField termField;
          private JTextField rateField;
          private JTextField paymentField;

          //Construct labels and text boxes
          private JLabel loanLabel = new JLabel("Mortgage Amount:          ");
          private JTextField p  = new JTextField(15);
          private JLabel termLabel = new JLabel("Term (in years):");
          private JTextField t = new JTextField(5);
          private JLabel rateLabel = new JLabel("Interest Rate:");
          private JTextField r = new JTextField(5);
          private JLabel paymentLabel = new JLabel("Payment:");
          private JTextField m = new JTextField(15);
          private JLabel displayPayment = new JLabel();

          //Construct Buttons
          private JButton calculateButton = new JButton("Calculate Payment");
          private JButton clearButton = new JButton("Clear");
          private JButton quitButton = new JButton ("Quit");


       public static void main(String[] args)
      {

      //Set look and feel for the interface
         try
         {
            UIManager.setLookAndFeel("com.sun.java.swing.plaf.motif.MotifLookAndFeel");
         }

         catch (Exception e)
         {


            }
         MortgagePay f = new MortgagePay();

         f.setSize(450,350);
         f.setTitle("Mortgage Payment Calculator");
         f.setResizable(false);
         f.setLocation(200,200);
         f.setVisible(true);
      }

       public MortgagePay()
      {
          //Bulid Container
          Container c = getContentPane();
              c.setLayout((new BorderLayout()));
          fieldPanel.setLayout(new GridLayout(8,1));
          FlowLayout rowSetup = new FlowLayout(FlowLayout.LEFT,5,3);
               firstRow.setLayout(rowSetup);
               secondRow.setLayout(rowSetup);
               thirdRow.setLayout(rowSetup);
               fourthRow.setLayout(rowSetup);

          buttonPanel.setLayout(new FlowLayout(FlowLayout.CENTER));
          buttonPanel.setLayout(new FlowLayout(FlowLayout.RIGHT));



          //add fields to rows
          firstRow.add(loanLabel);
          firstRow.add(p);
          secondRow.add(termLabel);
          secondRow.add(t);
          thirdRow.add(rateLabel);
          thirdRow.add(r);
          fourthRow.add(paymentLabel);
          fourthRow.add(m);
          fourthRow.add(displayPayment);

          //Add rows to panel
          fieldPanel.add(firstRow);
          fieldPanel.add(secondRow);
          fieldPanel.add(thirdRow);
          fieldPanel.add(fourthRow);
          //add button to panel
          buttonPanel.add(calculateButton);
          buttonPanel.add(clearButton);
          buttonPanel.add(quitButton);

          //Add panels to frame
          c.add(fieldPanel, BorderLayout.CENTER);
          c.add(buttonPanel, BorderLayout.SOUTH);

          //add fuctionality to the button
          calculateButton.addActionListener(this);
          clearButton.addActionListener(this);
          quitButton.addActionListener(this);

     }

       public void actionPerformed(ActionEvent e)
      {
              Object source = e.getSource();


               if(source == clearButton)
                  {
                  p.setText(null);
                  t.setText(null);
                  r.setText(null);
                  m.setText(null);

                  }
               if(source == quitButton)
               {
                     System.exit(0);
               }


               //This is going to call the method for doing the math
               mortCal();


       }

        public void mortCal()
        {
      {
            if(p.getText().trim().length()==0||r.getText().trim().length()==0||t.getText().trim().length()==0)
            {
                  displayPayment.setText(null);
                  return;
            }


               double principle = Double.parseDouble(p.getText());
               double rate = Double.parseDouble(r.getText());
               double term = Double.parseDouble(t.getText());
               double interest = (rate/100/12);
               double payment = (principle*interest)/(1-Math.pow(1/(1+interest), term*12));
               displayPayment.setText("" + NumberFormat.getCurrencyInstance().format(payment));
               displayPayment.setText(null);
               }
               }
   }

have you tried mine??

its working