NullPointerException / problem with listeners?

import java.util.*;

import java.io.*;

/**

NWSFB06.java - Receives Station Weather string extracting and formatting

data before returning it. Implements the NWS interface.

*/

public class NWSFB06 implements NWS

{

String strStationWeather, strAlt;

public NWSFB06 (String strStaWea)

{

strStationWeather = strStaWea + " ";

}

/** Returns the weather in one somewhat condensed but user friendly line

@param strAlt A 2 character string representing the altitude in thousands

@return A line with the weather for a location and altitude*/

public String getPrintLine (String strAlt)

{

return "The weather for " + getStationID() + " at " + strAlt + "000 feet is "

+ getAltWea(strAlt) + "";

}

/** Returns index of weather information for an altitude.

@param strAlt A 2 character string representing the altitude in thousands

@return An integer representing the starting point in stStationWeather for

the data associated with the altitude entered in the strAlt parameter*/

public String getStationID ()

{

String result;

result = strStationWeather.substring(0,3);

return result;

}

/** Returns weather information for an altitude.

@param strAlt A 2 character string representing the altitude in thousands

@return A 7 character string that contains weather data for a specific altitude*/

public String getAltWea(String strAlt)

{

String strOut = "";

int intPosition;

intPosition = getPos(strAlt);

/** Extracts the seven character string from Station Weather

Adds a space on the end so that we can easily work with the string */

strOut = strStationWeather.substring(intPosition,intPosition + 7) + " ";

/** We are looking for the end of the Altitude Weather and then

we pad the end with more spaces */

strOut = strOut.substring(0,strOut.indexOf(" ",0)) + "";

/** Now chop the thing down to EXACTLY seven spaces */

strOut = strOut.substring(0,7);

return strOut;

}

/** Returns index of weather information for an altitude.

@param strAlt A 2 character string representing the altitude in thousands

@return An integer representing the starting point in stStationWeather for

the data associated with the altitude entered in the strAlt parameter*/

public int getPos (String strAlt)

{

int intPos = Integer.parseInt(strAlt);

switch (intPos)

{

case 3:

intPos = 4;

break;

case 6:

intPos = 9;

break;

case 9:

intPos = 17;

break;

case 12:

intPos = 25;

break;

case 18:

intPos = 33;

break;

case 24:

intPos = 41;

break;

case 30:

intPos = 49;

break;

case 34:

intPos = 56;

break;

case 39:

intPos = 63;

break;

default:

break;

}

return intPos;

}

/** At a given altitude, returns the Wind Direction.

@param strAlt A 2 character string representing the altitude in thousands

@return A 3 character string indicating the direction of the wind in degrees*/

public String getWindDir(String strAlt)

{

String strWindDir;

int intPosition, intCompare;

intPosition = getPos(strAlt);

strWindDir = strStationWeather.substring(intPosition,intPosition + 2);

/** Checks for blanks and returns N/A if that is the case. If not, determines if the

direction is within normal parameters. If it is a zero is simply appended to the string.

Otherwise the direction is formatted first. Also checks to see if the Wind Speed is "calm"

and returns N/A for the direction in that case*/

if (strWindDir.equals(" "))

strWindDir = "N/A";

else

{

intCompare = Integer.parseInt(strWindDir);

if (intCompare >= 1 && intCompare <= 36)

{

strWindDir = intCompare + "0";

}

else if (intCompare >= 51 && intCompare <= 86)

{

intCompare -= 50;

strWindDir = intCompare + "0";

}

else if (intCompare == 99)

strWindDir = "N/A";

}

return strWindDir;

}

/** At a given altitude, returns the Wind Speed, in knots, as a two or three digit string.

@param strAlt A 2 character string representing the altitude in thousands

@return A 2-3 character string indicating the Wind Speed in knots*/

public String getWindSpeed(String strAlt)

{

String strWindSpeed, strCompare;

int intPosition, intCompare, intConversion;

intPosition = getPos(strAlt);

strWindSpeed = strStationWeather.substring(intPosition + 2,intPosition + 4);

strCompare = strStationWeather.substring(intPosition, intPosition + 2);

/** Checks for blanks and returns N/A if that is the case. Otherwise checks the

Wind Direction string to determine if the speed is over 99 knots or is calm formatting

the data if either exception occurs. If not it returns the knots as originally found

in the strStationWeather substring.*/

if (strWindSpeed.equals(" "))

strWindSpeed = "N/A";

else

{

intCompare = Integer.parseInt(strCompare);

intConversion = Integer.parseInt(strWindSpeed);

if (intCompare >= 1 && intCompare <= 36)

{

}

else if (intCompare >= 51 && intCompare <= 86)

{

intConversion += 100;

strWindSpeed = intConversion + "";

}

else if (intCompare == 99)

strWindSpeed = "calm";

}

return strWindSpeed;

}

/**Returns Wind Temperature based on altitude.

@param strAlt A 2 character string representing the altitude in thousands

@return A 3 character indicating Wind Temperature in degrees Celsius*/

public String getWindTemp(String strAlt)

{

String strWindTemp;

int intPosition, intAlt;

intPosition = getPos(strAlt);

strWindTemp = strStationWeather.substring(intPosition + 4,intPosition + 7);

/**Ensures that the temperatures returned for above 24000 feet are

automatically negative or if the altitude is 3000 "N/A" is returned

at there is no temperature information for this altitude.*/

intAlt = Integer.parseInt(strAlt);

if (intAlt > 24)

strWindTemp = "-" + strWindTemp;

else

if (intAlt < 6)

strWindTemp = "N/A";

return strWindTemp;

}

/** Returns the fully formatted weather for a location and altitude

@param strAlt A Two character string representing the altitude in thousands

@return A paragraph with the fully formatted weather data*/

public String getWeather(String strAlt)

{

String strAltitude, strStationID, strWeather;

strAltitude = " " + strAlt + "000 ";

strStationID = getStationID();

strWeather = getAltWea(strAlt);

return getPrintLine(strAlt)

+"\r\n which translates into:\r\n"

+ "Wind Direction of\t" + getWindDir(strAlt) + " degrees\r\n"

+ "Wind Speed of\t" + getWindSpeed(strAlt) + " knots\r\n"

+ "Wind Temperature of\t" + getWindTemp(strAlt) + " degrees Celsius\r\n";

}

/*

public void status(String strVar)

{

}

*/

}

eeka at 2007-7-12 8:32:47 >

ArrayList is very simple to use. It's a kind of dynamic array.

This class has some usefull methods:

- get(int index) : which returns the object at the index

- size() : returns the size

- add(Object o): Appends the specified element to the end of this list.

See :

http://java.sun.com/j2se/1.4.2/docs/api/java/util/ArrayList.html

By the way, you have the same problem with strApt[]

(strApt[counter] = fd.getStationID();)

java_2006a at 2007-7-12 8:32:47 >

import java.awt.*;

import java.awt.event.*;

import javax.swing.*;

import java.util.*;

import java.util.List;

import java.io.*;

public class WeatherForm07 extends JPanel {

/** Width of JFrame */

private int WIDTH = 400;

/** Height of JFrame */

private int HEIGHT = 375;

/** Main Window to hold form */

private JFrame frame;

/** The form within the frame */

private JPanel panel;

/** Main title on the form */

private JLabel lblTitle;

/** Label to hold the name of the programmer */

private JLabel lblProgrammer;

/** Label at top of airport names */

private JLabel lblAirport;

/** Label at top of nine altitudes */

private JLabel lblAltitude;

/** Label to hold the Wind Direction */

private JLabel lblDir;

/** Label to hold Wind Speed */

private JLabel lblSp;

/** Label to hold the Wind Temperature */

private JLabel lblTemp;

/** Static label at left of Wind Direction */

private JLabel lblPDir;

/** Static label at left of Wind Speed */

private JLabel lblPSp;

/** Static label at left of Wind Temperature */

private JLabel lblPTemp;

/** The Exit Button */

private JButton btnExit;

// Reference 701

/** Radio buttons for the Airport or Weather Station ID's */

private JRadioButton[] Apt = new JRadioButton[21];

/** Radio buttons for the nine altitudes */

private JRadioButton[] Alt = new JRadioButton[9];

// Reference 702

/** Object containing the code for decoding the Nat Weather Svc FD report */

private NWSFB06[] wea;

// Reference 703

private String[] strApt;// = new String[21];

/** Temporary variable to hold Airport Name */

private String strAirport;

/**

* Temporary variable to hold a number indicating which Airport radio button has been selected

*/

private int intAirport;

/** Array of Altitude Labels */

private String[] strAlt = { "3", "6", "9", "12", "18", "24", "30", "34", "39" };

/** Temporary variable to hold Altitude Labels */

private String strAltitude;

/**

* Temporary variable to hold a number indicating which altitude radio button has been selected

*/

private int intAltitude;

private JTextArea TA;

/** Weather Constructor */

public WeatherForm07() {

intAirport = 0; // initialize Airport

intAltitude = 3; // initialize Altitude

strAltitude = "3"; // initialize Altitude

// Reference 704

frame = new JFrame("Asgn A19007");

frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

/**

* Setting the Layout Manager to null enables you to precisely position controls using x, y coordinates

*/

panel = new JPanel(null);

panel.setPreferredSize(new Dimension(WIDTH, HEIGHT));

panel.setBackground(Color.lightGray);

lblTitle = new JLabel("Aviation Center");

/** This is an example of how to set the font */

lblTitle.setFont(new Font("Helvetica", Font.BOLD, 24));

/**

* The setSize() method sets the width and height of the object. 410 is the width, 20 is the height

*/

lblTitle.setSize(410, 20);

/**

* The setLocation() method is where you set the x,y location of the object. In this case, the title is set 15

* pixels from the left margin and 25 pixels from the top margin

*/

lblTitle.setLocation(15, 25);

/** Setting the color of the font */

lblTitle.setForeground(Color.blue);

/**

* Now that you are done setting the properties, add it to the panel.

*/

panel.add(lblTitle);

lblProgrammer = new JLabel("programmed by ...");

lblProgrammer.setSize(200, 20);

lblProgrammer.setLocation(100, 50); // 100 from Left, 50 from Top

panel.add(lblProgrammer);

/** Radio Buttons - Airports */

lblAirport = new JLabel("Airport");

lblAirport.setSize(200, 20);

lblAirport.setLocation(15, 100);

panel.add(lblAirport);

// Reference 705

/**

* Here you will put code that will:

*

* /** Open the file and read the first record

*/

int counter = 0;

try {

Scanner fileScan = new Scanner(new File("FBIN.txt"));

/** The following has the effect of skipping the upper records */

fileScan.nextLine(); // (Extracted From...)

fileScan.nextLine(); // FDUW02 KWBC 231410

fileScan.nextLine(); // DATA BASED ON 231200Z

fileScan.nextLine(); // VALID 231800Z

fileScan.nextLine(); // Blank

fileScan.nextLine(); // FT 3000 6000

List weaList = new ArrayList();///////////CHANGE HERE

List strAptList = new ArrayList();///////////CHANGE HERE

while (fileScan.hasNext()) {

/** Get each record and pass to NWSFD */

String strStaWea = fileScan.nextLine();

if ((strStaWea.length()) < 70) {

strStaWea += " ";

}

NWSFB06 fd = new NWSFB06(strStaWea);

// System.out.println(strStaWea.length());

weaList.add(fd);///////////CHANGE HERE

/*wea = new NWSFB06[21];

wea[counter] = fd;// OR new NWSFB06(strStaWea);

*/

// System.out.println("begin problem?");

//strApt[counter] = fd.getStationID();

strAptList.add(fd.getStationID());///////////CHANGE HERE

counter++;

}

wea = new NWSFB06[weaList.size()];///////////CHANGE HERE

for (int i = 0; i < weaList.size(); i++) {///////////CHANGE HERE

wea[i] = (NWSFB06)weaList.get(i);///////////CHANGE HERE

}

strApt = new String[strAptList.size()];///////////CHANGE HERE

for (int i = 0; i < strAptList.size(); i++) {///////////CHANGE HERE

strApt[i] = (String)strAptList.get(i);///////////CHANGE HERE

}

}

catch (Exception e) {///////////CHANGE HERE

System.out.println("File not found.");

e.printStackTrace();

}

// Reference 707

/**

* Add your radio buttons for Airports here To do this declare an array of JRadioButtons above and then set the

* title, size and location

*/

RBListener aptListener = new RBListener();

ButtonGroup groupApt = new ButtonGroup();

int x = 15, y = 100;

int count = 0;

for (int rowCount = 0; rowCount < 3; rowCount++)// loop to count the row

{

y += 25;// top

x = 15;// left

for (int colCount = 0; colCount < 7; colCount++)// loop to count the column

{

Apt[count] = new JRadioButton(strApt[count], true); // create a JRadioButton object

Apt[count].addActionListener(aptListener);// create the actionLinstener

Apt[count].setSize(60, 20); // wide, high - set the size

Apt[count].setLocation(x, y);

groupApt.add(Apt[count]); // add the object to the radio button group

panel.add(Apt[count]);

System.out.println(count);

count++;

x += 60;

}

}

/** Label for the Altitude */

lblAltitude = new JLabel("Altitude in Thousands");

lblAltitude.setSize(200, 20);

lblAltitude.setLocation(15, 175);

panel.add(lblAltitude);

/** Add you radio buttons for Altitude here */

RBListener altListener = new RBListener();

ButtonGroup groupAlt = new ButtonGroup();

for (count = 0; count < 9; count++) {

Alt[count] = new JRadioButton(strAlt[count], true);

groupAlt.add(Alt[count]);

Alt[count].addActionListener(altListener);

Alt[count].setSize(40, 20); // wide, high

x = 200; // pixels from top

y = (count * 40) + 15; // pixels from left

Alt[count].setLocation(y, x); // left,top

panel.add(Alt[count]);

}

/** Labels for the Answers */

lblPDir = new JLabel("Direction: ");

lblPDir.setSize(100, 20);

lblPDir.setLocation(15, 225);

panel.add(lblPDir);

lblDir = new JLabel("--");

lblDir.setSize(100, 10);

lblDir.setLocation(115, 225);

panel.add(lblDir);

lblPSp = new JLabel("Speed: ");

lblPSp.setSize(100, 20);

lblPSp.setLocation(15, 250);

panel.add(lblPSp);

lblSp = new JLabel("--");

lblSp.setSize(100, 10);

lblSp.setLocation(115, 250);

panel.add(lblSp);

lblPTemp = new JLabel("Temp C: ");

lblPTemp.setSize(100, 20);

lblPTemp.setLocation(15, 275);

panel.add(lblPTemp);

lblTemp = new JLabel("--");

lblTemp.setSize(100, 20);

lblTemp.setLocation(115, 275);

panel.add(lblTemp);

/** Buttons */

btnExit = new JButton("Exit");

btnExit.addActionListener(new ButtonListener());

btnExit.setSize(350, 20);

btnExit.setLocation(15, 300);

panel.add(btnExit);

frame.getContentPane().add(panel);

} // end of DemoForm07

public void display() {

frame.pack();

frame.setVisible(true);

}

/** Code for what to do when the user presses EXIT */

private class ButtonListener implements ActionListener {

public void actionPerformed(ActionEvent event) {

if (event.getSource() == btnExit) {

System.exit(0); // return to operating system

}

}

} // end of ButtonListener

/**

* Code for what to do when the user clicks on one of the radio buttons

*/

private class RBListener implements ActionListener {

public void actionPerformed(ActionEvent event) {

Object source = event.getSource();

for (int count = 0; count < 21; count++) {

if (source == Apt[count]) {

intAirport = count;

}

}

for (int count = 0; count < 9; count++) {

if (source == Alt[count]) {

strAltitude = strAlt[count];

}

}

/**

* Use your NWSFD object to determine the wind direction, speed and temperature.

*/

lblDir.setText(wea[intAirport].getWindDir(strAltitude));

lblSp.setText(wea[intAirport].getWindSpeed(strAltitude));

lblTemp.setText(wea[intAirport].getWindTemp(strAltitude));

lblAirport.setText("Airport=" + strApt[intAirport]);

lblAltitude.setText("Altitude=" + strAltitude + "000");

} // end of action performed

} // end of RBListener

public static void main(String[] args) {

new WeatherForm07().display();

}

}

java_2006a at 2007-7-12 8:32:47 >