Applet processing a file works locally but fails in website

Question

I've been bashing my head in on this problem for a few days now. I've done my full share of Googling, and I'm hoping I can find someone here that is more experienced than I (not hard to find haha) that can decipher my problem.

Scenario: I developed a Java Applet that implements a Swing GUI. Background work: The Applet gathers records from a large "phone book" excel file (.csv) and stores them in a Map data structure. The phone book contains about 106,000 records, and on the 34,586th record, I get an ArrayIndexOutOfBoundsException that I cannot make sense of. The exception only occurs when I'm running the applet on my personal website. The applet runs perfectly fine with no errors while testing in my IDE (NetBeans) and running the .html file (the one that contains the applet) on my local machine. The output and exception that is thrown while running on my website is as follows (I cut most of the records to save space):

Java Console

Kary,Webber,2826 East 12th Ave.,Memphis,TN,38168,901-749-1834
Erinn,Rocha,2132 East Main Ave.,Memphis,TN,38168,865-414-5105
Gina,Lane,71 South First St. Apt. 11,Memphis,TN,38168,731-485-1129
Patsy,Hart,661 East 11th St.
java.lang.ArrayIndexOutOfBoundsException: 3
at Implementation.PersonnelDatabase.addRecordFromFields(PersonnelDatabase.java:192)
at Implementation.PersonnelDatabase.initDBFromFile(PersonnelDatabase.java:215)
at Implementation.PersonnelDatabase.processData(PersonnelDatabase.java:239)
at Implementation.PersonnelDatabaseApplet$2.doInBackground(PersonnelDatabaseApplet.java:78)
at Implementation.PersonnelDatabaseApplet$2.doInBackground(PersonnelDatabaseApplet.java:69)
at javax.swing.SwingWorker$1.call(Unknown Source)
at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)
at java.util.concurrent.FutureTask.run(Unknown Source)
at javax.swing.SwingWorker.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)

As you can see, on the 34,586th record (beginning with Patsy,Hart), it outputs midway through her address. The full record is as follows: Patsy,Hart,661 East 11th St. Apt. 195,Memphis,TN,38168,555-555-5555 .

Below are the sections of code that are most logically influenced by the exception.

Object tag in HTML file

<object type="application/x-java-applet" height="400" width="300">
  <param name="codebase" value="classes" />
  <param name="code" value="Implementation/PersonnelDatabaseApplet.class" />
  <param name="archive" value="PersonnelDatabase.jar" />
  Applet failed to run. No Java plug-in was found.
</object>

PersonnelDatabase class (processes background data):

/*
 * Create a new record using an appropriately ordered set of fields and add it to the data base
 */
public void addRecordFromFields(String[] fields)
{
    // Read record attributes in, one at a time
    Record thisRecord = new Record();
    thisRecord.setFirstName(fields[0]);
    thisRecord.setLastName(fields[1]);
    thisRecord.setAddress(fields[2]);
    thisRecord.setCity(fields[3]);
    thisRecord.setState(fields[4]);
    thisRecord.setZipCode(fields[5]);
    thisRecord.setPhoneNo(fields[6]);
    addRecord(thisRecord);
}

// O( n )
/**
 * Destroy the current data base and load new data from a file.
 * @param filename the file to use as a source
 * @throws IOException: Either file not found or IO error
 */
public void initDBFromFile(URL url) throws IOException
{
    // Open and read the file
    InputStream in = url.openStream();
    BufferedReader filein = new BufferedReader(new InputStreamReader(in));
    // Read record file, parse lines, and add records to data base
    String line = filein.readLine();
    while(line != null) {
        System.err.println(line);
        String[] fields = line.split(",");
        addRecordFromFields(fields);
        line = filein.readLine();
    }
    filein.close();
}

/**
 * Loads the default library and provides for interaction with the data
 * via the JPanel GUI inputs.
 * @param args
 * @throws IOException 
 */
public String processData(String input, int selection, URL url)
{
    //Create the main library object
    PersonnelDatabase dbiLib = new PersonnelDatabase();
    System.err.println(url);
    // Try to read the default library
    try
    {
        dbiLib.initDBFromFile(url);
    }
    catch (IOException e)
    {
        System.err.println("File IO Error");
        e.printStackTrace();
        System.exit(1);
    }
    // Queries can be simulated by typing into the console in Eclipse, and using Ctrl-d (Ctrl-z in Windows) when finished.
    // For example: "searchLastName,Smith" would print a list of all people with the last name of Smith.
    Iterable<Record> result = null;
    String[] fields = new String[2];
    if (input.contains(",")) {
        fields = input.split(",");
    }

    switch(selection) {
        case 0: result = dbiLib.searchByFirstName(input); break;
        case 1: result = dbiLib.searchByLastName(input); break;
        case 2: result = dbiLib.searchByFullName(fields[0].trim(), fields[1].trim()); break;
        case 3: result = dbiLib.searchByCity(input); break;
        case 4: result = dbiLib.searchByState(input); break;
        case 5: result = dbiLib.searchByCityState(fields[0].trim(), fields[1].trim()); break;
        case 6: result = dbiLib.searchByZip(input); break;
        case 7: result = dbiLib.searchByPhoneNumber(input); break;
        case 8: String[] newFields = new String[fields.length-1];
                System.arraycopy(fields, 1, newFields, 0, fields.length-1);
                dbiLib.addRecordFromFields(newFields);
                return "Record added successfully!\nEnter a query or add another record.";
        default: return "Invalid query.\nEnter another query or add a record.";
    }

PersonnelDatabaseApplet class (initializes GUI, gathers input, and displays output):

public void init() {
    /* Create and display the applet */
    try {
        java.awt.EventQueue.invokeAndWait(new Runnable() {

            @Override
            public void run() {
                initComponents();
            }
        });
    } catch (Exception e) {
        System.err.println("Creation of GUI did not successfully complete.");
    }
}

// Process inputs in the background.
SwingWorker worker = new SwingWorker<String, Void>() {
    @Override
    public String doInBackground() {
        URL url = null;
        try {
            url = new URL(getCodeBase(), fileToRead);
        }
        catch(MalformedURLException e){}
        personnelDatabase = new PersonnelDatabase();
        final String output = personnelDatabase.processData(input, selection, url);
        return output;
    }

    @Override
    public void done() {
        processingLabel.setVisible(true);
        try {
            textToDisplay = get(15, TimeUnit.SECONDS);
        } catch (InterruptedException ignore) {
            ignore.printStackTrace();
        } catch (TimeoutException e) {
            e.printStackTrace();
        } catch (ExecutionException e) {
            String why = null;
            Throwable cause = e.getCause();
            if(cause != null) {
                why = cause.getMessage();
                cause.printStackTrace();
            } else {
                why = e.getMessage();
                e.printStackTrace();
            }
            System.err.println("Error retrieving request: " + why);
            }
        if(worker.isDone() && textToDisplay != null) {
            processingLabel.setVisible(false);
            outputTextArea.setText(textToDisplay);
        }
    }
};

private void searchButtonActionPerformed(java.awt.event.ActionEvent evt) {                                             
selection = searchComboBox.getSelectedIndex();
input = valueTextField.getText();
processingLabel.setVisible(true);

worker.execute();

}

Link to the Applet on my personal website: http://www.ryan-taylor.me/Applied%20Maps/build/PersonnelDatabaseApplet.html

I'm fairly certain the error has nothing to do with the excel data itself as this program runs just fine in NetBeans and when running the html on my local machine. I'm guessing it has something to do with Swing (threads), but I'm not sure. I made changes to help with transferring data between Swing threads by making use of the SwingWorker, but I had no luck. I guess there's always the possibility I missed something when implementing it.

I also thought about signing the jar, but the file that I'm processing is stored online - not a local machine - so I didn't see a real need.

If anyone has any suggestions, I would greatly appreciate it!

Answer 1

Looks like the array index that's out of bounds is 3, because the input line contains only three fields and you're trying to access the fourth one (index 3) without checking to verify that it actually exists. The error is in

thisRecord.setCity(fields[3]);

because the array fields has only three elements. At

    String[] fields = line.split(",");
    addRecordFromFields(fields);

when you get to

Patsy,Hart,661 East 11th St.

array fields will be created with only 3 entries.

If the number of fields is expected to be constant then you should reject input lines that don't have the right number of fields. If the number of fields can vary, then you must check the actual number returned and extract only those elements that actually exist.

Answer 2

It looks like something is causing the file to be truncated when you run the applet in a browser. My guess is that you are fetching the file from a web server, and either the server or the browser is silently enforcing some download limit. (Or may be the file got truncated when you uploaded it ...)

Answer 3

I suspect a data race between your worker and another thread that is exposed by network latency. Two things may bear closer scrutiny:

1. Using invokeAndWait() to initialize the GUI is reasonable, as long as no further processing is done on the initial thread.

2. Your worker is unusual in not invoking publish(), as a way to process() records on the event dispatch thread, for example.