CODEWITHSUNDEEP
javaserializationapplet
Ryan Stull
Ryan Stull

Reputation: 1096

Serializing objects in an applet

Ok, simply put I am making a quiz game in a java applet, and I want to serialize an object which stores the high scores. When I do this it works perfectly in eclipse but not in a browser.

Here is the code of my applet where it reads the file: and yes I have all of the appropriate imports

package histApplet;

public class QuizApplet extends Applet
{
private static final String TRACKERLOC = "histApplet/track.ser";
private StatsTracker tracker;
private int difflevel = 1;
//other instance variables


public void init()
{
    //other code
    if(new File(TRACKERLOC).exists())
    {
        tracker = null;
        FileInputStream fis = null;
        ObjectInputStream in = null;
        try
        {
            fis = new FileInputStream(TRACKERLOC);
            in = new ObjectInputStream(fis);
            tracker = (StatsTracker)in.readObject();
            in.close();
        }
        catch(IOException ex)
        {
            ex.printStackTrace();
        }
        catch(ClassNotFoundException ex)
        {
            ex.printStackTrace();
        }
    }
    else
    {
        tracker = new StatsTracker(difflevel);
    }
    //other code
}

And here is my html code

<html>
<head><title>QuizApplet</title></head>
<body>

<center><applet code="histApplet/QuizApplet.class" height=550 width=700>
</applet></center>

</body>
</html>

If I comment out this code it works in a browser but otherwise doesn't. I'm not sure why this doesn't work, and any help would be greatly appreciated.

Upvotes: 0

Views: 845

Answers (3)

Paŭlo Ebermann
Paŭlo Ebermann

Reputation: 74750

As written by David, applets can't access the local file system.

They can send data to the host they came from (and receive answers from there), so you could store the highscores on the server, if you have some server-side program which accepts these highscores there.

An alternative would be using a JNLP-deployed applet, then your applet could access an applet-specific local storage with a PersistenceService.

Upvotes: 0

David Oliv&#225;n
David Oliv&#225;n

Reputation: 2725

Java Applets execute in a sandbox within the browser, so have limited access to resources in the client machine running the applet (into the browser). File system can't be accessed by an Applet, as explained in several sites SecuringJava, Oracle.

You need to sign your Applet (trusted code) in order to get access to the file system, Oracle.

Upvotes: 1

Andrew Thompson
Andrew Thompson

Reputation: 168825

See my answer on how to write into a text file in Java.

Upvotes: 1

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