Problems getting Graph to show

[rhivka]

Hey guys! This is really a great forum and you people are a lot nicer than the Sun guys Anyway...I need some help with this program again. Thought I would post a new question for a new problem. Thanks to hardwired.. I've come a long way with it, but the graph is not showing after calculations are made and amortization is done...when the user clicks on Show Graph, the new window pops up but it is blank. Could someone take a look and let me know what you think? Thanks!

Code:

import java.awt.*;
import java.awt.event.*;
import java.awt.font.*;
import java.awt.geom.*;
import java.io.*;
import java.text.*;
import javax.swing.*;
import javax.swing.border.*;
import javax.swing.JComboBox;

public class MC extends JFrame implements ActionListener {
    JTextField principalTxt, termTxt, rateTxt, monthlyPaymentTxt;
    JTextArea displayArea;
    JButton calculateButton, graphButton, amortizeButton, clearButton, exitButton;
    JComboBox options;

    //formatting variables
    DecimalFormat df = new DecimalFormat("\u00A4#,##0.00"); //currency
    DecimalFormat pf = new DecimalFormat("#,##0.00%");      //percentages
    DecimalFormat mi = new DecimalFormat("#,##0.000%");     //percentages

    // Can these 6 be removed and declared as local variables?
    int term = 0;
    double principal = 0;
    double rate = 0;
    double monthlyPayment = 0;
    double interest = 0;
    int notePeriod = 0;

    int[] termArray;
    double[] rateArray;
    private float[] principalAmts;
    private float[] interestAmts;

    public MC() {
        super ("Mortgage Payment Calculator by S Kemen");
        setSize(550, 500);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        load();
        setVisible(true);

        // Initialize components.
        JPanel row1 = new JPanel();
        JLabel mortgageLabel = new JLabel("MORTGAGE PAYMENT CALCULATOR", JLabel.CENTER);

        JPanel row2 = new JPanel(new GridLayout(1, 2));
        JLabel principalLabel = new JLabel("Mortgage Principal $",JLabel.LEFT);
        principalTxt = new JTextField(10);

        JPanel row3 = new JPanel(new GridLayout(1, 2));
        JLabel termLabel = new JLabel("Mortgage Term (Yrs)",JLabel.LEFT);
        termTxt = new JTextField(10);

        JPanel row4 = new JPanel(new GridLayout(1, 2));
        JLabel rateLabel = new JLabel("Interest Rate (%)", JLabel.LEFT);
        rateTxt = new JTextField(10);

        JPanel row5 = new JPanel(new GridLayout(1, 2));
        JLabel presetLabel = new JLabel("Preset Term and Interest Rate:", JLabel.LEFT);

        JPanel row6 = new JPanel(new GridLayout(1,2));
        options = new JComboBox();
        MessageFormat mf = new MessageFormat("{0} years at {1,number,#.##}%");
        JLabel choiceLabel = new JLabel(" (choose rate)");
        for (int i = 0; i < termArray.length; i++) {
            options.addItem(mf.format(new Object[] { new Integer(termArray [i]),
                                                     new Double(rateArray[i])}));
        }

        JPanel row7 = new JPanel(new GridLayout(1, 2));
        JLabel monthlyPaymentLabel = new JLabel("Monthly Payment $", JLabel.LEFT);
        monthlyPaymentTxt = new JTextField(10);

        //create buttons
        JPanel button = new JPanel(new FlowLayout(FlowLayout.CENTER, 10, 10));
        graphButton = new JButton("Display Graph");
        amortizeButton = new JButton("Amortize Payments");
        clearButton = new JButton("Clear");
        exitButton = new JButton("Exit");
        calculateButton = new JButton("Calculate");

        //create textarea to display Amortize output
        displayArea = new JTextArea(10, 45);
        JScrollPane scroll = new JScrollPane(displayArea);

        Container pane = getContentPane();
        // Set layout before adding components.
        pane.setLayout(new BoxLayout( pane, BoxLayout.Y_AXIS));

        Border rowborder = new EmptyBorder( 3, 10, 3, 10 );

        pane.add(row1);
        row1.add(mortgageLabel);
        row1.setMaximumSize( new Dimension( 10000, row1.getMinimumSize().height));
        row1.setBorder( rowborder);

        pane.add(row2);
        row2.add(principalLabel);
        row2.add(principalTxt);
        row2.setMaximumSize( new Dimension( 10000, row2.getMinimumSize().height));
        row2.setBorder( rowborder);

        pane.add(row3);
        row3.add(termLabel);
        row3.add(termTxt);
        row3.setMaximumSize( new Dimension( 10000, row3.getMinimumSize().height));
        row3.setBorder( rowborder);

        pane.add(row4);
        row4.add(rateLabel);
        row4.add(rateTxt);
        row4.setMaximumSize( new Dimension( 10000, row4.getMinimumSize().height));
        row4.setBorder( rowborder);

        pane.add(row5);
        row5.add(presetLabel);
        row5.setMaximumSize( new Dimension( 10000, row4.getMinimumSize().height));
        row5.setBorder( rowborder);

        pane.add(row6);
        row6.add(choiceLabel);
        row6.setMaximumSize( new Dimension( 10000, row4.getMinimumSize().height));
        row6.setBorder( rowborder);

        JPanel radioPanel = new JPanel();
        radioPanel.setLayout(new FlowLayout(FlowLayout.LEFT, 4, 4 ));
        radioPanel.add(options);
        pane.add(radioPanel);
        radioPanel.setMaximumSize( new Dimension( 10000,
                                         radioPanel.getMinimumSize().height));
        radioPanel.setBorder( rowborder);


        pane.add(row7);
        row7.add(monthlyPaymentLabel);
        row7.add(monthlyPaymentTxt);
        monthlyPaymentTxt.setEnabled(false);  //set payment amount uneditable
        monthlyPaymentTxt.setFocusable(false);
        row7.setMaximumSize( new Dimension( 10000, row5.getMinimumSize().height));
        row7.setBorder( rowborder);

        //Add buttons
        button.add(calculateButton);
        button.add(clearButton);
        button.add(exitButton);
        button.add(amortizeButton);
        button.add(graphButton);
        pane.add(button);
        button.setMaximumSize( new Dimension( 10000, button.getMinimumSize().height));

        //scroll text pane for Amortize output
        scroll.setBorder(BorderFactory.createEmptyBorder(10,10,10,10));
        pane.add(scroll);
        setContentPane(pane);

        //add listeners for buttons and combo box
        options.addActionListener(this);
        clearButton.addActionListener(this);
        exitButton.addActionListener(this);
        calculateButton.addActionListener(this);
        amortizeButton.addActionListener(this);
        graphButton.addActionListener(this);

    }

    public void actionPerformed(ActionEvent event) {
        Object command = event.getSource();

        if(command == calculateButton) { //function for Calculate button
            try {
                principal = Double.parseDouble(principalTxt.getText());
            } catch(NumberFormatException e) {
                //catch null pointer exception if Principal is null
                JOptionPane.showMessageDialog(null, "Invaild Entry!  Please Try Again",
                                              "ERROR", JOptionPane.ERROR_MESSAGE);
            }
            try {
                //Get input from Term text box, checked first before combo box
                term = Integer.parseInt(termTxt.getText());
                rate = Double.parseDouble(rateTxt.getText()); //Input from Rate text box
            } catch(NumberFormatException e)  {
                //If Term and Rate are null, buttons are checked for input values
                //Set rate and term based on which item in the combobox is selected


                //If no option is selected and combo box null,
                // this is an actual error.
                JOptionPane.showMessageDialog(null, "Invaild Entry! " +
                                              "Please Try Again",
                                              "ERROR", JOptionPane.ERROR_MESSAGE);
            }
            interest = rate / 100 / 12;  //Monthly interst rate
            notePeriod = term * 12;      //Number of months over which loan is amortized

            //calculation formula
            monthlyPayment = (principal * interest) /
                                   (1 - Math.pow(1 + interest, -notePeriod));

            monthlyPaymentTxt.setText("" + df.format(monthlyPayment));
        }

        if(command == clearButton) { //Function for Clear button
            principalTxt.setText("");
            monthlyPaymentTxt.setText("");
            rateTxt.setText("");
            termTxt.setText("");
            displayArea.setText("");
        }

        if(command == exitButton) { //Function for Exit button
             System.exit(0);
        }
        if (command == amortizeButton) { //Function for Amortize button
            //Amoritization variables
            double loanBalance = notePeriod * monthlyPayment;
            // You need to use the member variables with these two names
            // so you can send them to your GraphPanel. Instantiate them
            // here and fill the elements in this loop. The member
            // variables remain null and choke up GraphPanel.
            double interestPaid = 0;       //Interest paid on the loan
            double monthlyPrincipal = 0;   //Principal in each monthly payment
            //running total of principal after payment
            double principalBalance = principal;
            //String for output
            String titles = "Month\t Principal\t\tInterest\t\tBalance\n";

            displayArea.setText(titles);
            displayArea.append("");        //Inserts a blank line

            interestAmts  = new float[term*12];
            principalAmts = new float[term*12];

            //This loop is used to calculate and display the payment schedule information
            for(int counter = 0; counter < term * 12 - 0; counter++) { //start outer loop
                //start inner loop
                interestPaid = principalBalance * interest;
                interestAmts[counter] = (float)interestPaid;
                monthlyPrincipal = monthlyPayment - interestPaid;
                principalAmts[counter] = (float)monthlyPrincipal;
                loanBalance = loanBalance - monthlyPayment;
                principalBalance = principalBalance - monthlyPrincipal;

                //formatting for output
                displayArea.setCaretPosition(0);
                displayArea.append((counter +1) + ")\t" +
                                    df.format(monthlyPrincipal)+"\t\t" +
                                    df.format(interestPaid)+"\t\t" +
                                    df.format(principalBalance)+"\n");
            }
        }
        if (command == graphButton) { //Function for Graph button
            JDialog d = new JDialog(this, false);
            d.getContentPane().add(new GraphPanel(principalAmts, interestAmts));
            d.setSize(800,600);
            d.setLocation(200,100);
            d.setVisible(true);
        }
    }

    //reading from sequential file
    private void load() {
        Reader fis;
        try {
            fis = new InputStreamReader(getClass().getResourceAsStream("data.txt"));
            BufferedReader br = new BufferedReader( fis );
            termArray = new int[4];
            rateArray = new double[4];
            String line;
            int i = 0;
            while((line = br.readLine()) != null) {
                String[] s = line.split(",");
                termArray[ i ] = Integer.parseInt(s[0].trim());
                rateArray[ i ] = Double.parseDouble(s[1].trim());
                i++;
            }

            br.close();
        } catch ( Exception e1 ) {
            e1.printStackTrace(  );
        }
    }

class GraphPanel extends JPanel
{
    final int
        HPAD = 60,
        VPAD = 40;
    int[] data;
    Font font;
    float[] principalAmts;
    float[] interestAmts;

    public GraphPanel(float[] principalAmts, float[] interestAmts)
    {

        font = new Font("lucida sans regular", Font.PLAIN, 16);
        setBackground(Color.white);
    }

    protected void paintComponent(Graphics g)
       {
           super.paintComponent(g);

           Graphics2D g2 = (Graphics2D)g;
           g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                               RenderingHints.VALUE_ANTIALIAS_ON);
           g2.setFont(font);
           FontRenderContext frc = g2.getFontRenderContext();
           int w = getWidth();
           int h = getHeight();
           // scales
           float xInc = (w - HPAD - VPAD) / (interestAmts.length - 1);//11f;  //distance between each point
           float yInc = (h - 2*VPAD) / 10f;
           int[] dataVals = getDataVals();        //min and max values for y-axis
           float yScale = dataVals[2] / 10f;

           // ordinate (y - axis)
           g2.draw(new Line2D.Double(HPAD, VPAD, HPAD, h - VPAD));
           // plot tic marks
           float x1 = HPAD, y1 = VPAD, x2 = HPAD - 3, y2;
           for(int j = 0; j < 10; j++)
           {
               g2.draw(new Line2D.Double(x1, y1, x2, y1));
               y1 += yInc;
           }
           // labels
           String text; LineMetrics lm;
           float xs, ys, textWidth, height;
           for(int j = 0; j <= 10; j++)
           {
               text = String.valueOf(dataVals[1] - (int)(j * yScale));
               textWidth = (float)font.getStringBounds(text, frc).getWidth();
               lm = font.getLineMetrics(text, frc);
               height = lm.getAscent();
               xs = HPAD - textWidth - 7;
               ys = VPAD + (j * yInc) + height/2;
               g2.drawString(text, xs, ys);
                     if(j == 0) g2.drawString("Principal", xs, ys - 15);
           }

           // abcissa (x - axis)
           g2.draw(new Line2D.Double(HPAD, h - VPAD, w - VPAD, h - VPAD));
           // tic marks
           x1 = HPAD; y1 = h - VPAD; y2 = y1 + 3;
           for(int j = 0; j < interestAmts.length; j++)
           {
               g2.draw(new Line2D.Double(x1, y1, x1, y2));
               x1 += xInc;
           }
           // labels
           ys = h - VPAD;
           for(int j = 0; j < interestAmts.length; j++)
           {
               text = String.valueOf(j + 1);
               textWidth = (float)font.getStringBounds(text, frc).getWidth();
               lm = font.getLineMetrics(text, frc);
               height = lm.getHeight();
               xs = HPAD + j * xInc - textWidth/2;
               g2.drawString(text, xs, ys + height);
                     if( j == (interestAmts.length - 1)) g2.drawString("Year", (int)w /2 , ys + height + 15);
           }

           // plot data
             float yy2 = 0, yy1 = 0, xx2 = 0, xx1;
           x1 = HPAD;
             xx1 = HPAD;
           yScale = (float)(h - 2*VPAD) / dataVals[2];

           for(int j = 0; j < interestAmts.length; j++)
           {
             g.setColor(Color.blue);
             y1 = VPAD + (h - 2*VPAD) - (principalAmts[j] - dataVals[0]) * yScale;
                 g2.fillOval((int)x1, (int)y1 - 2, 5, 5);

               if(j > 0)
               g2.draw(new Line2D.Double(x1, y1, x2, y2));
               x2 = x1;
               y2 = y1;
               x1 += xInc;

             g.setColor(Color.red);
             yy1 = VPAD + (h - 2*VPAD) - (interestAmts[j] - dataVals[0]) * yScale;
                 g2.fillOval((int)xx1, (int)yy1 - 1, 5, 5);
                  if(j > 0)
               g2.draw(new Line2D.Double(xx1, yy1, xx2, yy2));
               xx2 = xx1;
               yy2 = yy1;
               xx1 += xInc;

           }
    }

    private int[] getDataVals()
    {
        int max = Integer.MIN_VALUE;
        int min = Integer.MAX_VALUE;
          int j = interestAmts.length -1;
          max = (int)principalAmts[j];
          min = (int)interestAmts[j];
        int span = max - min;
        return new int[] { min, max, span };
    }
}

    public static void main(String[] args) {
        MC smc = new MC();
    }
 }

The data.txt file contains the following:
7,5.35
15,5.5
20,5.65
30,5.75

[hardwired]

The first thing I notice in looking at your GraphPanel class is that you did not assign the member variables (principalData, interestData) to the local variables (p, i) in the constructor. This leaves the member variables with the value of null and, when running the class liks this results in this exception in the console:

Code:

C:\jexp>java MC
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
        at GraphPanel.paintComponent(mc.java:311)

Make the assignment in your constructor with

Code:

    public GraphPanel(float[] p, float[] i) {
        principalData = p;
        interestData = i;
        font = new Font("lucida sans regular", Font.PLAIN, 16);
        setBackground(Color.white);
    }

and see what happens.

About your last thread:
When I posted a recommendation to change setEnabled to setFocusable on the monthlyPaymentTxt I meant that you should replace the first, setEnabled line with the second, setFocusable line. Use one or the other, not both.

Code:

        // Eliminate/remove this next line.
//        monthlyPaymentTxt.setEnabled(false);  //set payment amount uneditable
        // Leave this line in.
        monthlyPaymentTxt.setFocusable(false);

Also, this comment can be removed from the ActionListener

Code:

// You need to use the member variables with these two names
// so you can send them to your GraphPanel. Instantiate them
// here and fill the elements in this loop. The member
// variables remain null and choke up GraphPanel.

We handled it in the last post and I forgot to remove it.

[rhivka]

Hi again hardwired ... So if I'm understanding you correctly, the graph code should look like the following? Because it was like this before and I thought it wouldn't work for some reason and changed a lot of variables. I thought they had to be principalAmts, interestAmts.

Code:

//creates class for graphpanel
class GraphPanel extends JPanel
{
    final int
        HPAD = 60,
        VPAD = 40;
    int[] data;
    Font font;
     float[] principleData;
     float[] interestData;


    public GraphPanel(float[] p, float[] i)
    {

     principleData = p;
     interestData = i;

        font = new Font("lucida sans regular", Font.PLAIN, 16);
        setBackground(Color.white);
    }

   protected void paintComponent(Graphics g)
       {
           super.paintComponent(g);

           Graphics2D g2 = (Graphics2D)g;
           g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                               RenderingHints.VALUE_ANTIALIAS_ON);
           g2.setFont(font);
           FontRenderContext frc = g2.getFontRenderContext();
           int w = getWidth();
           int h = getHeight();
           // scales
           float xInc = (w - HPAD - VPAD) / (interestData.length - 1);//11f;  //distance between each plot
           float yInc = (h - 2*VPAD) / 10f;
           int[] dataVals = getDataVals();        //min and max values for y-axis
           float yScale = dataVals[2] / 10f;

           // ordinate (y - axis)
           g2.draw(new Line2D.Double(HPAD, VPAD, HPAD, h - VPAD));
           // plot tic marks
           float x1 = HPAD, y1 = VPAD, x2 = HPAD - 3, y2;
           for(int j = 0; j < 10; j++)
           {
               g2.draw(new Line2D.Double(x1, y1, x2, y1));
               y1 += yInc;
           }
           // labels
           String text; LineMetrics lm;
           float xs, ys, textWidth, height;
           for(int j = 0; j <= 10; j++)
           {
               text = String.valueOf(dataVals[1] - (int)(j * yScale));
               textWidth = (float)font.getStringBounds(text, frc).getWidth();
               lm = font.getLineMetrics(text, frc);
               height = lm.getAscent();
               xs = HPAD - textWidth - 7;
               ys = VPAD + (j * yInc) + height/2;
               g2.drawString(text, xs, ys);
                     if(j == 0) g2.drawString("Principle", xs, ys - 15);
           }

           // abcissa (x - axis)
           g2.draw(new Line2D.Double(HPAD, h - VPAD, w - VPAD, h - VPAD));
           // tic marks
           x1 = HPAD; y1 = h - VPAD; y2 = y1 + 3;
           for(int j = 0; j < interestData.length; j++)
           {
               g2.draw(new Line2D.Double(x1, y1, x1, y2));
               x1 += xInc;
           }
           // labels
           ys = h - VPAD;
           for(int j = 0; j < interestData.length; j++)
           {
               text = String.valueOf(j + 1);
               textWidth = (float)font.getStringBounds(text, frc).getWidth();
               lm = font.getLineMetrics(text, frc);
               height = lm.getHeight();
               xs = HPAD + j * xInc - textWidth/2;
               g2.drawString(text, xs, ys + height);
                     if( j == (interestData.length - 1)) g2.drawString("Year", (int)w /2 , ys + height + 15);
           }

           // plot data
             float yy2 = 0, yy1 = 0, xx2 = 0, xx1;
           x1 = HPAD;
             xx1 = HPAD;
           yScale = (float)(h - 2*VPAD) / dataVals[2];

           for(int j = 0; j < interestData.length; j++)
           {
             g.setColor(Color.blue);
             y1 = VPAD + (h - 2*VPAD) - (principleData[j] - dataVals[0]) * yScale;
                 g2.fillOval((int)x1, (int)y1 - 2, 5, 5);

               if(j > 0)
               g2.draw(new Line2D.Double(x1, y1, x2, y2));
               x2 = x1;
               y2 = y1;
               x1 += xInc;

             g.setColor(Color.red);
             yy1 = VPAD + (h - 2*VPAD) - (interestData[j] - dataVals[0]) * yScale;
                 g2.fillOval((int)xx1, (int)yy1 - 1, 5, 5);
                  if(j > 0)
               g2.draw(new Line2D.Double(xx1, yy1, xx2, yy2));
               xx2 = xx1;
               yy2 = yy1;
               xx1 += xInc;

           }
    }

    private int[] getDataVals()
    {
        int max = Integer.MIN_VALUE;
        int min = Integer.MAX_VALUE;
          int j = interestData.length -1;
          max = (int)principleData[j];
          min = (int)interestData[j];
        int span = max - min;
        return new int[] { min, max, span };
    }
  }
}

About the other changes... I kinda knew but forgot to make corrections and take out the comments.

One other thing... I wanted the input from the ComboBox to insert into the TextBoxes and then be calculated so I entered the following under ActionEvents:

Code:

 if (command==options){
	int index = options.getSelectedIndex();
             if (index>=0) {
             termTxt.setText(termArray[index]);
       	rateTxt.setText(pf.format(rateArray[index]));
	}
     }

But it's throwing the following error:

java:170: setText(java.lang.String) in javax.swing.text.JTextComponent cannot be applied to (int)
termTxt.setText(termArray[index]);

[rhivka]

Nvm I fixed that last one with:
termTxt.setText(Integer.toString(termArray[index]));

But now... I'm back to a blank UI when it starts. Should I post it all again?

[hardwired]

The next thing to do is check on the data that shows up in GraphPanel with something like this:

Code:

public GraphPanel(float[] p, float[] i)
{
    principleData = p;
    interestData = i;
    System.out.printf("principalData = %s%ninterestData = %s%n",
                       java.util.Arrays.toString(principalData),
                       java.util.Arrays.toString(interestData));
    font = new Font("lucida sans regular", Font.PLAIN, 16);
    setBackground(Color.white);
}

Start tracking down where things aren't going the way you'd like.

[rhivka]

I figured out why I was getting the blank screen.. I had 2 copies saved and I was running the wrong one, which didn't have the data.txt file present...which gave the blank when I ran the program. It seems to run great now, just need to adjust one area where when it takes the input from the combobox, it enters it in the textbox as ie. 556.00% instead of 5.56%. But that is minor...working on it now

[rhivka]

Thanks for the help, hardwired. You're a life saver. Have a good night!