Homework: for loop output to jTextPane based on jTextBox variables

FIRST: I do not want a hand out, or the answer. I just need a few comments so I can find out where I am going wrong.

Second, my code is sloppy. I did not rename my GUI fields so a lot of them are default. I have been working on this for roughly 15 hours.

What I had is a non-GUI mortgage calculator from Java 1 which implemented a loop and displayed monthly payments in various forms such as principal payment, interest payment, etc.

For Java 2 I need to put this in a GUI.

What I have now is a GUI which has 3 radio buttons. Clicking these buttons populate text fields with "default" loan variables. When I press calculate the result is displayed in another text box. I also have a TextPane- this pane needs to show the scroll of my output, the monthly payments broken down. When I run my program it calculates correctly except only shows the last calculated payment in the text pane. It is also number incorrectly, being short by the initial month.

I understand my code is ugly- I do not need a rewrite, but I would and do appreciate any advice on what I am doing incorrectly or sloppily.

I believe the problem lies in my for loop near the bottom.

Code:

---

package mortgageweek2;

//MortgageWeek2GUI.java
//Created on Dec 11, 2011, 7:06:53 PM
//@author Chris
import javax.swing.*;
import java.awt.*;
import java.text.DecimalFormat; //Added import to output currency correctly
public class MortgageWeek2GUI extends javax.swing.JFrame {
    /** Creates new form MortgageWeek2GUI */
    int loanAmount; //Declare all variables.
float result;
double rateR;
double termT;

    public MortgageWeek2GUI() {
        initComponents();
    }
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">
    private void initComponents() {

        buttonGroup1 = new javax.swing.ButtonGroup();
        jLabel1 = new javax.swing.JLabel();
        jLabel2 = new javax.swing.JLabel();
        jButton1 = new javax.swing.JButton();
        jTextField1 = new javax.swing.JTextField();
        jTextField2 = new javax.swing.JTextField();
        jTextField3 = new javax.swing.JTextField();
        jTextField4 = new javax.swing.JTextField();
        jLabel3 = new javax.swing.JLabel();
        jLabel4 = new javax.swing.JLabel();
        jLabel5 = new javax.swing.JLabel();
        jLabel6 = new javax.swing.JLabel();
        jButton2 = new javax.swing.JButton();
        jButton3 = new javax.swing.JButton();
        jRadioButton1 = new javax.swing.JRadioButton();
        jRadioButton2 = new javax.swing.JRadioButton();
        jRadioButton3 = new javax.swing.JRadioButton();
        jLabel7 = new javax.swing.JLabel();
        jSeparator1 = new javax.swing.JSeparator();
        jSeparator2 = new javax.swing.JSeparator();
        jScrollPane1 = new javax.swing.JScrollPane();
        jTextArea1 = new javax.swing.JTextArea();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        jLabel1.setText("Java II Mortgage Calculator with GUI");

        jLabel2.setText("Christopher Dill 12/11/2011");

        jButton1.setText("Exit");
        jButton1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton1ActionPerformed(evt);
            }
        });

        jLabel3.setText("Principle Loan Amount:");

        jLabel4.setText("Interest Rate:");

        jLabel5.setText("Loan Term in Years:");

        jLabel6.setText("Monthly Payment: ");

        jButton2.setText("Calculate");
        jButton2.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton2ActionPerformed(evt);
            }
        });

        jButton3.setText("Clear");
        jButton3.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton3ActionPerformed(evt);
            }
        });

        buttonGroup1.add(jRadioButton1);
        jRadioButton1.setText("7 years at 5.35%");
        jRadioButton1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jRadioButton1ActionPerformed(evt);
            }
        });

        buttonGroup1.add(jRadioButton2);
        jRadioButton2.setText("15 years at 5.5%");
        jRadioButton2.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jRadioButton2ActionPerformed(evt);
            }
        });

        buttonGroup1.add(jRadioButton3);
        jRadioButton3.setText("30 years at 5.75%");
        jRadioButton3.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jRadioButton3ActionPerformed(evt);
            }
        });

        jLabel7.setText("Use the radio buttons to calculate some predetermined loan values");

        jTextArea1.setColumns(20);
        jTextArea1.setRows(5);
        jScrollPane1.setViewportView(jTextArea1);

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(layout.createSequentialGroup()
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                            .addComponent(jLabel1)
                            .addComponent(jLabel2)
                            .addGroup(layout.createSequentialGroup()
                                .addComponent(jButton2)
                                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                                .addComponent(jButton3)
                                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                                .addComponent(jButton1)))
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 125, Short.MAX_VALUE))
                    .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                        .addComponent(jSeparator1)
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addComponent(jRadioButton1)
                            .addComponent(jRadioButton3)
                            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                                .addComponent(jRadioButton2)
                                .addGap(125, 125, 125)))
                        .addComponent(jLabel7)
                        .addComponent(jSeparator2, javax.swing.GroupLayout.DEFAULT_SIZE, 326, Short.MAX_VALUE))
                    .addGroup(layout.createSequentialGroup()
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addComponent(jLabel6)
                            .addComponent(jLabel5)
                            .addComponent(jLabel4)
                            .addComponent(jLabel3, javax.swing.GroupLayout.PREFERRED_SIZE, 122, javax.swing.GroupLayout.PREFERRED_SIZE))
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addComponent(jTextField1, javax.swing.GroupLayout.DEFAULT_SIZE, 194, Short.MAX_VALUE)
                            .addComponent(jTextField2, javax.swing.GroupLayout.DEFAULT_SIZE, 194, Short.MAX_VALUE)
                            .addComponent(jTextField3, javax.swing.GroupLayout.DEFAULT_SIZE, 194, Short.MAX_VALUE)
                            .addComponent(jTextField4, javax.swing.GroupLayout.PREFERRED_SIZE, 78, javax.swing.GroupLayout.PREFERRED_SIZE))))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(jScrollPane1, javax.swing.GroupLayout.DEFAULT_SIZE, 259, Short.MAX_VALUE)
                .addContainerGap())
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(layout.createSequentialGroup()
                        .addComponent(jLabel1)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                        .addComponent(jLabel2)
                        .addGap(18, 18, 18)
                        .addComponent(jLabel7)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                        .addComponent(jSeparator1, javax.swing.GroupLayout.PREFERRED_SIZE, 12, javax.swing.GroupLayout.PREFERRED_SIZE)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                        .addComponent(jRadioButton1)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                        .addComponent(jRadioButton2)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                        .addComponent(jRadioButton3)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                        .addComponent(jSeparator2, javax.swing.GroupLayout.PREFERRED_SIZE, 10, javax.swing.GroupLayout.PREFERRED_SIZE)
                        .addGap(34, 34, 34)
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                            .addComponent(jLabel3))
                        .addGap(18, 18, 18)
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addComponent(jTextField2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                            .addComponent(jLabel4))
                        .addGap(18, 18, 18)
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addComponent(jLabel5)
                            .addComponent(jTextField3, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                        .addGap(18, 18, 18)
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addComponent(jTextField4, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                            .addComponent(jLabel6))
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 55, Short.MAX_VALUE)
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addComponent(jButton1, javax.swing.GroupLayout.Alignment.TRAILING)
                            .addComponent(jButton3, javax.swing.GroupLayout.Alignment.TRAILING)
                            .addComponent(jButton2, javax.swing.GroupLayout.Alignment.TRAILING)))
                    .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 387, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addContainerGap())
        );

        pack();
    }// </editor-fold>

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                       
// This is the code for the EXIT button.
        System.exit(0);
}                                       

private void jButton3ActionPerformed(java.awt.event.ActionEvent evt) {                                       
// This is the code for the CLEAR button.
        jTextField1.setText("");
        jTextField2.setText("");
        jTextField3.setText("");
        jTextField4.setText("");
        jTextArea1.setText("");
        buttonGroup1.clearSelection(); // Make the clear button unselect all radio buttons.
}                                       

private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {                                       
// Code here will make the calculation run and conver types.

//Link variables to text fields in the GUI.
    loanAmount = Integer.parseInt(jTextField1.getText());
    rateR = Double.parseDouble(jTextField2.getText());
    termT = Double.parseDouble(jTextField3.getText());
    DecimalFormat Currency = new DecimalFormat("$#0.00");  // Provides 2 decimal place format for output.
// Perform calculations.
    result = (float) ((loanAmount * (rateR /100/12)) / (1 - Math.pow((1 + (rateR/100/12)), -(termT*12)))); // Perform entire calculation.
    jTextField4.setText(String.valueOf(Currency.format(result))); // Change value to string and output. Also apply formatting for $ and 2 decimal places.
        double termTotal = termT * 12;
        double monthlyInterest = loanAmount * (rateR / (12 * 100));
        double monthlyPrincipal = result - monthlyInterest;
        double balanceLeft = loanAmount - monthlyPrincipal;
        double rateCalc = rateR/100/12;
        int lineCount = 0;
    for (int Number=1; Number < termTotal; Number++) {

            // Begin array.
                balanceLeft += (balanceLeft * rateCalc);  // Changes to the balance throughout the loop processing.                                       
                balanceLeft -= result;                                                                                                       
                monthlyInterest = balanceLeft * rateCalc;                               
                monthlyPrincipal = result - monthlyInterest;
                lineCount++;
        if (lineCount > 1000) {  // This will display 1000 lines at a time.                                                                                               
        try {Thread.sleep (0);  // Pauses for 0 millaseconds
                lineCount = 0;}
        catch(InterruptedException e){} // This does nothing except provide Java with a needed argument.

}                                       
        jTextArea1.setText(Number + "  " +Currency.format(balanceLeft) + // Main output
                "  " +Currency.format(monthlyInterest) +
                "  " +Currency.format(monthlyPrincipal)); 
        //jTextArea1.setText(String.valueOf(Currency.format(result))); // Used to text my TextArea1

}}
private void jRadioButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                             
       
    if (jRadioButton1.isSelected()) { // Apply field choices based on radio button selection.
        jTextField1.setText("200000");
        jTextField2.setText("5.35");
        jTextField3.setText("7");}
}                                           

private void jRadioButton2ActionPerformed(java.awt.event.ActionEvent evt) {
if (jRadioButton2.isSelected()) { // Change field variables.
        jTextField1.setText("200000");
        jTextField2.setText("5.5");
        jTextField3.setText("15"); }
}

private void jRadioButton3ActionPerformed(java.awt.event.ActionEvent evt) {
    if (jRadioButton3.isSelected()) { // Change to last field variables.
        jTextField1.setText("200000");
        jTextField2.setText("5.75");
        jTextField3.setText("30"); }
}

    public static void main(String args[]) {
        /* Set the Nimbus look and feel */
        //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
        /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
        * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html
        */
        try {
            for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
                if ("Nimbus".equals(info.getName())) {
                    javax.swing.UIManager.setLookAndFeel(info.getClassName());
                    break;
                }
            }
        } catch (ClassNotFoundException ex) {
            java.util.logging.Logger.getLogger(MortgageWeek2GUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(MortgageWeek2GUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(MortgageWeek2GUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(MortgageWeek2GUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }
        //</editor-fold>

        /* Create and display the form */
        java.awt.EventQueue.invokeLater(new Runnable() {

// End of variable Declaration and calculation lines.
            public void run() {
                new MortgageWeek2GUI().setVisible(true);
            }
        });
    }
    // Variables declaration - do not modify
    private javax.swing.ButtonGroup buttonGroup1;
    private javax.swing.JButton jButton1;
    private javax.swing.JButton jButton2;
    private javax.swing.JButton jButton3;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel jLabel2;
    private javax.swing.JLabel jLabel3;
    private javax.swing.JLabel jLabel4;
    private javax.swing.JLabel jLabel5;
    private javax.swing.JLabel jLabel6;
    private javax.swing.JLabel jLabel7;
    private javax.swing.JRadioButton jRadioButton1;
    private javax.swing.JRadioButton jRadioButton2;
    private javax.swing.JRadioButton jRadioButton3;
    private javax.swing.JScrollPane jScrollPane1;
    private javax.swing.JSeparator jSeparator1;
    private javax.swing.JSeparator jSeparator2;
    private javax.swing.JTextArea jTextArea1;
    private javax.swing.JTextField jTextField1;
    private javax.swing.JTextField jTextField2;
    private javax.swing.JTextField jTextField3;
    private javax.swing.JTextField jTextField4;
    // End of variables declaration
}

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Welcome to forum. Do not post the same question multiple times.

Hey Eranga, you killed my post! ;)

Abbreviated version:

setText() performs as advertised and sets the text in the text area - effectively replacing what was there. SO you end up with a single line. Check out the JTextArea API docs for something more appropriate.

Do you intend the for loop to run from Number=1? Count how many times the loop will execute. If anything, it'll be the *last* month that is missed.

Number should be number, and readable method names would improve the code.

I could have sworn I had tried the append method. Anyhow, I changed it to append, changed the formatting around, and made it a lower case n- and the code runs correctly, though it still displays one less than correct line numbers and the last result is a negative. Thanks for the help!

And sorry for the double post it was unintentional.

Quote:

---

it still displays one less than correct line numbers and the last result is a negative

---

What is the for loop now? And what does the text area display when it's finished?

Your question is about a JTextPane, which doesn't have an append() method.

Also, there is no such thing as a JTextBox.

Be specific and use proper class names when asking a question.

Also, next time post an Short, Self Contained, Correct Example with your question. We don't have time to read through 300+ lines of code to guess what you are doing.