help I am having trouble getting the field to fill in

[Tami Hart]

I have my program working while I am using the drop down menue, However I want to be able to select the JCheckBox and it will allow me to enter any amounts and it will do the math and fill in the monthly payment and the chart. here is my program:

import java.io.*;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.text.NumberFormat;
import java.math.*;
  
public class scroll2t extends JFrame implements ActionListener, ItemListener
  
 {//Beginning of Program
  
   // Fields for Principle
   JPanel row1 = new JPanel();
   JLabel dollar = new JLabel("How much are you borrowing?");
   JTextField money = new JTextField(" ", 15);
  
   // Fields for Term and Rate
   JPanel row2 = new JPanel();
   JLabel choice = new JLabel("Select Year & Rate:");
   JCheckBox altchoice = new JCheckBox("Alt. Method");
   JTextField YR = new JTextField(" ", 4);
   JTextField RT = new JTextField(" ", 4);
  
   //Jcombobox R=rate,Y=year
   String[] RY =
       {"7 years at 5.35%", "15 years at 5.5 %", "30 years at 5.75%", " "};
   JComboBox mortgage = new JComboBox(RY);
 
   // Fields for Payment
   JPanel row3 = new JPanel();
   JLabel payment = new JLabel("Your monthly payment will be:");
   JTextField owe = new JTextField(" ", 15);
 
   //Scroll Pane and Text Area
   JPanel row4 = new JPanel();
   JLabel amortization = new JLabel("Amortization:");
   JTextArea chart = new JTextArea(" ", 7, 22);
   JScrollPane scroll = new JScrollPane(chart,
   JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
   JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
   StringBuffer amt = new StringBuffer();
   Container pane = getContentPane();
   FlowLayout flow = new FlowLayout(FlowLayout.LEFT);
   JButton Cal = new JButton("Calculate");
   public scroll2t()
   { //Start of JFrame
 
     // Title and Exit of JFrame
     super("Q's Mortgage and Amortization Calculator");
     setSize(475, 328);
     setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 
     //JFrame layout
     
     
     pane.setLayout(flow);
 
     //Input output fields added to JFrame
     row1.add(dollar);
     row1.add(money);
     pane.add(row1);
     mortgage.setSelectedIndex(3);
     mortgage.addActionListener(this);
     row2.add(altchoice);
     altchoice.addItemListener(this);
     row2.add(choice);
     YR.setEditable(false);
     RT.setEditable(false);
     row2.add(YR);
     row2.add(RT);
     row2.add(mortgage);
     pane.add(row2);
     row3.add(payment);
     row3.add(owe);
     pane.add(row3);
     owe.setEditable(false);
 
     //Scroll Pane added to JFrame
     row4.add(amortization);
     chart.setEditable(false);
     row4.add(scroll);
     pane.add(row4);
 
     //Executable Button- Clear,Exit, Calculate
     JPanel row5 = new JPanel();
     JButton clear = new JButton("Clear");
     clear.addActionListener(this);
     row5.add(clear);
     pane.add(row5);
 
     JButton exit = new JButton("Exit");
     exit.addActionListener(this);
     row5.add(exit);
     
     Cal.setEnabled(false);
     row5.add(Cal);
     pane.add(row5);
     
     //Column Titles for Text Area
     
     amt.append("Pmt#\tPrincipal\tInterest\tBalance\n");
     chart.setText(amt.toString());
     setContentPane(pane);
     setVisible(true);
   } //End of JFrame
public void itemStateChanged(ItemEvent ie)
{
     int status = ie.getStateChange();
     if (status == ItemEvent.SELECTED)
     {
mortgage.setEnabled(false);
YR.setEditable(true);
RT.setEditable(true);
Cal.setEnabled(true);
     }
     else 
     {
       mortgage.setEnabled(true);
       YR.setEditable(false);
       RT.setEditable(false);
       Cal.setEnabled(false);
     
     }
}
public void actionPerformed(ActionEvent ae)//Calculations and Button executions
{ //Start actionPerformed
 
  String command = ae.getActionCommand();
  // Exit program
     if (command == "Exit")System.exit(0);
     
//Define variables loan1  //Define loan2
double Principal = 0;  int Year2 = 15;
int Year = 7;          double Rate2 = 0.055;
double Rate = 0.0535;  int Year3 = 30;
double Interest = 0;      double Rate3 = 0.0575;
double Monthly = 0;
NumberFormat currency = 
NumberFormat.getCurrencyInstance();
 
  // Cal button
  if (command== "Calculate")
  {
int y = Integer.parseInt(YR.getText());
double r = Double.parseDouble(RT.getText())/1200;
double P = Double.parseDouble(money.getText());
double In = r / 100 / 12.0;
double M = P * (In / (1 - Math.pow(In + 1, -12.0 * y)));
owe.setText(currency.format(Double.toString(M)));
for (int i=0; i<y*12; i++)
     {
double interestAccrued=Principal*Interest;
double principalPaid=Monthly-interestAccrued;
amt.append(i+1 + "\t" +currency.format(principalPaid) 
+  "\t" + currency.format(interestAccrued)
+ "\t" + currency.format(Principal) + "\n");
chart.setText(amt.toString());
Principal=Principal+interestAccrued-Monthly;
     }
      
  }
  // Clear fields
     if (command == "Clear")
     {
       Principal = 0.0F;
       money.setText(null);
       mortgage.setSelectedIndex(3);
       owe.setText(null);
       chart.setText(null);
     }
     // check box
     
     //Execute Combo Array 0
     if(mortgage.getSelectedIndex()==0)
     {
     //mortgage.setSelectedIndex(0);
     mortgage.getSelectedItem().toString();
     Principal = Double.parseDouble(money.getText());
     Interest = Rate / 12.0;
     Monthly = Principal * (Interest / (1 - Math.pow(Interest + 1, -12.0 * Year)));
     owe.setText(currency.format(Monthly));
     for (int i=0; i<Year*12; i++)
     {
double interestAccrued=Principal*Interest;
double principalPaid=Monthly-interestAccrued;
amt.append(i+1 + "\t" +currency.format(principalPaid) 
+  "\t" + currency.format(interestAccrued)
+ "\t" + currency.format(Principal) + "\n");
chart.setText(amt.toString());
Principal=Principal+interestAccrued-Monthly;
     }
      
     }
     //Execute Combo Array 1
     if(mortgage.getSelectedIndex()==1)
     {
     //mortgage.setSelectedIndex(1);
     mortgage.getSelectedItem().toString();
     Principal = Double.parseDouble(money.getText());
     Interest = Rate2 / 12.0;
     Monthly = Principal * (Interest / (1 - Math.pow(Interest + 1, -12.0 * Year2)));
     owe.setText(currency.format(Monthly));
     for (int i=0; i<Year2*12; i++)
     {
double interestAccrued=Principal*Interest;
double principalPaid=Monthly-interestAccrued;
amt.append(i+1 + "\t" +currency.format(principalPaid) 
+  "\t" + currency.format(interestAccrued)
+ "\t" + currency.format(Principal) + "\n");
chart.setText(amt.toString());
Principal=Principal+interestAccrued-Monthly;
     }
     }
     //Execute Combo Array 2
     if(mortgage.getSelectedIndex()==2)
     {
     //mortgage.setSelectedIndex(2);
     mortgage.getSelectedItem().toString();
     Principal = Double.parseDouble(money.getText());
     Interest = Rate3 / 12.0;
     Monthly = Principal * (Interest / (1 - Math.pow(Interest + 1, -12.0 * Year3)));
     owe.setText(currency.format(Monthly));
     for (int i=0; i<Year3*12; i++)
     {
double interestAccrued=Principal*Interest;
double principalPaid=Monthly-interestAccrued;
amt.append(i+1 + "\t" +currency.format(principalPaid) 
+  "\t" + currency.format(interestAccrued)
+ "\t" + currency.format(Principal) + "\n");
chart.setText(amt.toString());
Principal=Principal+interestAccrued-Monthly;
     }
     }
         
} //End actionPerformed
 
   public static void main(String args[])throws IOException
   {
     scroll2 Calc = new scroll2();
   }
}

[ edited to preserve formatting using the [code] and [/code] UBB tags -ds ]
[ July 22, 2004: Message edited by: Dirk Schreckmann ]

[Dirk Schreckmann]

When posting code, please be sure to surround the code with the [code] and [/code] UBB Tags. This will help to preserve the formatting of the code, thus making it easier to read and understand.

[Dirk Schreckmann]

Moving this to the Swing / JFC / AWT forum...

[Craig Wood]

The general idea is to check to see if altchoice is selected and then figure out your variables y and r based on what you discover. Then move into your calculating and finally into the displaying of monthly data.

Note the use of the arrays terms and rates as storage devices. You get the index of the selection in method and use this to collect your term and rate data.

Rewriting your program so that blocks of repeated code (used in different places or situations) appear only once is called refactoring.

Once your gui is onscreen all the action is focused in and through the event code. If you keep the code in the listeners simple and call methods to do the work it will make the logic easy to follow, design and understand.

import java.io.*;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.text.NumberFormat;
import java.math.*;
 
public class CalcTest extends JFrame implements ActionListener, ItemListener
{
    // Fields for Principle
    JPanel row1 = new JPanel();
    JLabel dollar = new JLabel("How much are you borrowing?");
    JTextField money = new JTextField("", 15);
 
    // Fields for Term and Rate
    JPanel row2 = new JPanel();
    JLabel choice = new JLabel("Select Year & Rate:");
    JCheckBox altchoice = new JCheckBox("Alt. Method");
    JTextField YR = new JTextField("", 4);
    JTextField RT = new JTextField("", 4);
 
    //Jcombobox R=rate,Y=year
    String[] RY = {
        "7 years at 5.35%", "15 years at 5.5 %", "30 years at 5.75%", " "
    };
    JComboBox mortgage = new JComboBox(RY);
 
    // Fields for Payment
    JPanel row3 = new JPanel();
    JLabel payment = new JLabel("Your monthly payment will be:");
    JTextField owe = new JTextField(" ", 15);
 
    //Scroll Pane and Text Area
    JPanel row4 = new JPanel();
    JLabel amortization = new JLabel("Amortization:");
    JTextArea chart = new JTextArea(" ", 7, 22);
    JScrollPane scroll = new JScrollPane(chart, JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
                                         JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
    StringBuffer amt = new StringBuffer();
    Container pane = getContentPane();
    FlowLayout flow = new FlowLayout(FlowLayout.LEFT);
    JButton Cal = new JButton("Calculate");
    NumberFormat currency = NumberFormat.getCurrencyInstance();
 
    public CalcTest()
    {
        // Title and Exit of JFrame
        super("Q's Mortgage and Amortization Calculator");
        setSize(475, 328);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 
        //JFrame layout
        pane.setLayout(flow);
 
        //Input output fields added to JFrame
        row1.add(dollar);
        row1.add(money);
        pane.add(row1);
        mortgage.setSelectedIndex(3);
        mortgage.addActionListener(this);
        mortgage.setActionCommand("mortgage");
        row2.add(altchoice);
        altchoice.addItemListener(this);
        row2.add(choice);
        YR.setEditable(false);
        RT.setEditable(false);
        row2.add(YR);
        row2.add(RT);
        row2.add(mortgage);
        pane.add(row2);
        row3.add(payment);
        row3.add(owe);
        pane.add(row3);
        owe.setEditable(false);
 
        //Scroll Pane added to JFrame
        row4.add(amortization);
        chart.setEditable(false);
        row4.add(scroll);
        pane.add(row4);
 
        //Executable Button- Clear,Exit, Calculate
        JPanel row5 = new JPanel();
        JButton clear = new JButton("Clear");
        clear.addActionListener(this);
        row5.add(clear);
        pane.add(row5);
 
        JButton exit = new JButton("Exit");
        exit.addActionListener(this);
        row5.add(exit);
 
        Cal.setEnabled(false);
        Cal.addActionListener(this);
        row5.add(Cal);
        pane.add(row5);
 
        setContentPane(pane);
        setVisible(true);
    } //End of constructor
 
    private void calculate()
    {
        String loanAmount = money.getText();
        if(loanAmount.equals(""))
            return;
        double P = Double.parseDouble(loanAmount);
        int y;
        double r;
 
        if(altchoice.isSelected())
        {
            if(YR.getText().equals("") || RT.getText().equals(""))
                return;
            y = Integer.parseInt(YR.getText());
            r = Double.parseDouble(RT.getText());
        }
        else
        {
            int index = mortgage.getSelectedIndex();
            if(index == 3)
                return;
            int[] terms = { 7, 15, 30 };
            double[] rates = { 5.5, 5.35, 5.75 };
            y = terms[index];
            r = rates[index];
        }
        double In = r / (100 * 12.0);
        double M = P * (In / (1 - Math.pow(In + 1, -12.0 * y)));
        owe.setText(currency.format(M));
        //Column Titles for Text Area
        chart.setText("Pmt#\tPrincipal\tInterest\tBalance\n");
        for (int i = 0; i < y * 12; i++)
        {
            double interestAccrued = P * In;
            double principalPaid = M - interestAccrued;
            chart.append(i + 1 + "\t" + currency.format(principalPaid) 
                       + "\t" + currency.format(interestAccrued)
                       + "\t" + currency.format(P) + "\n");
            P = P + interestAccrued - M;
        }
    }
 
    public void itemStateChanged(ItemEvent ie)
    {
        int status = ie.getStateChange();
        if (status == ItemEvent.SELECTED)
        {
            mortgage.setEnabled(false);
            YR.setEditable(true);
            RT.setEditable(true);
            Cal.setEnabled(true);
        }
        else 
        {
            mortgage.setEnabled(true);
            YR.setEditable(false);
            RT.setEditable(false);
            Cal.setEnabled(false);
        }
    }
 
    public void actionPerformed(ActionEvent ae)//Calculations and Button executions
    {
        String command = ae.getActionCommand();
        // Exit program
        if (command.equals("Exit"))
            System.exit(0);
 
        // Cal button
        if (command.equals("Calculate") || command.equals("mortgage"))
            calculate();
 
        // Clear fields
        if (command.equals("Clear"))
        {
            money.setText(null);
            mortgage.setSelectedIndex(3);
            owe.setText(null);
            chart.setText(null);
        }
    } //End actionPerformed
 
    public static void main(String args[]) throws IOException
    {
        new CalcTest();
    }
}