Serializable

[scottfree]

Hi there, new here.
I have a java application which uses serializable classes.
The serializable classes contain JList objects with DefaultListModels.
My problem is that I have managed to save the file and then when I open the file again, the ListModel is empty.
Is this a problem with Java?
Are ListModels serializable?
Thanks in advance for any help.

[mikeBarr81]

i don't know why it's empty, but if it wasn't Serializable it wouldn't let you write it to a file. Everything that is being written has to be serializable or an exception is thrown.

[cjard]

dont forget to fill a list with data before writing it to file.. kinda causes empty lists to be written if they dont have anything in them

[mikeBarr81]

lol that would help

[scottfree]

Thanks guys but nothing has helped.
I have a class which is called FileAdminIO which is used to do all the saving and reading etc.
I have now built little checks which check the ListModels to see if they are empty at the time of saving and reading. When I save the file, I get no error but then when I reload that same file, I get the message that the ListModel is empty.
This is driving me crazy but I think I will leave it for a few days and come bak with a fresh outlook.
Thanks for the suggestions though.

[mikeBarr81]

well without seeing any code I doubt anyone will be able to offer much in depth help. Post the full class on here and someone might see something wrong

[cjard]

w3rd

[scottfree]

[FONT=courier new][SIZE=1]
/*
Firstly the class which handles the File IO
The ListModels are checked before they are written to file and if they are empty, a warning is printed on screen
The checks are done again when the file is read and warnings shown if empty.
*/

public class FileAdminIO
{
  File f = null;
  File dir = null;

  public FileAdminIO (String filename)
  {
    // the directory where the file is to be written is initialized
    dir = new File("projects/");
    if (!dir.exists())
    {
      // check if the directory exists, if not: create it
      dir.mkdirs();
      create_fragebogen.showInfoMessage("Directory: "+dir.getAbsolutePath()+" created!");
    }
    f = new File("projects/"+filename);
    try
    {
      if (!f.exists())
      {
	f.createNewFile();
	create_fragebogen.showInfoMessage("File: "+f.getAbsolutePath()+" created!");
      }
    }
    catch (IOException ioe)
    {
      create_fragebogen.showErrorMessage("ObjectOutputStream could not be opened: "
			       + f.getAbsolutePath() + "\nException:" + ioe);
    }
  }

  public FileAdminIO (File openFile)
  {
    f = new File(openFile.getAbsolutePath());
    if (!f.exists())
    {
      create_fragebogen.showErrorMessage("File \""+openFile.getAbsolutePath()+"\" doesn´t exist");
    }
  }


  public void save (Project inProject)
  {
    try
    {
      // Just a warning if there are no Pages to save in Project
      if (inProject.getQPagesListModel().isEmpty())
      {
	create_fragebogen.showWarningMessage("FileAdminIO save(Project inProject): inProject QPagesListModel is empty!!");
      }
      // creates stream to write to file
      ObjectOutputStream oos = new ObjectOutputStream (new FileOutputStream(f.getAbsolutePath()));
      // write the Project Object to file
      oos.writeObject(inProject);
      // write everything from buffer
      oos.flush();
      // close the stream
      oos.close();
    }
    catch (FileNotFoundException fnfe)
    {
      create_fragebogen.showErrorMessage("File could not be opened: " + f.getAbsolutePath());
    //  create_fragebogen.showWarningMessage("Exception: " + fnfe);
    }
    catch (IOException ioe)
    {
      create_fragebogen.showErrorMessage("ObjectOutputStream could not be opened:" + f.getAbsolutePath());
    //  create_fragebogen.showWarningMessage("Exception: " + ioe);
    }
  }

  public Project read()
  {
    Project result = null;
    if (f.exists() && (f.length() > 0))
    {
      try
      {
	// create stream to read data from file
	ObjectInputStream ois = new ObjectInputStream (new FileInputStream(f.getAbsolutePath()));
	// read Object out of the stream and cast to Project
	result = (Project) ois.readObject();

	// Just a warning if there are no pages in loaded Project
	if (result.getQPagesListModel().isEmpty())
	{
	  create_fragebogen.showWarningMessage("FileAdminIO read(): QPagesListModel is empty");
	}

	// close stream
	ois.close();
      }
      catch(FileNotFoundException fnfe)
      {
	create_fragebogen.showErrorMessage("File could not be opened: " + f.getAbsolutePath());
	System.out.println("Exception: " + fnfe);
      }
      catch (StreamCorruptedException sce)
      {
	create_fragebogen.showErrorMessage("ObjectOutputStream is corrupt:" + f.getAbsolutePath());
	System.out.println("Exception: " + sce);
	//System.exit (0);
      }
      catch (OptionalDataException ode)
      {
	create_fragebogen.showErrorMessage("Data in ObjectOutputStream is corrupt:" + f.getAbsolutePath());
	System.out.println("Exception: " + ode);
      }
      catch (ClassNotFoundException cnfe)
      {
	create_fragebogen.showErrorMessage("Data could not be read from ObjectOutputStream:" + f.getAbsolutePath());
	System.out.println("Exception: " + cnfe);
      }
      catch (IOException ioe)
      {
	create_fragebogen.showErrorMessage("ObjectOutputStream could not be opened:" + f.getAbsolutePath());
	System.out.println("Exception: " + ioe);
      }
    }
    else
    {
      create_fragebogen.showErrorMessage ("No File with the name "+ f.getAbsolutePath() +"found from which a project could be read.");
    }
    // return Project Object to System
    return result;
  }

}


/* Now the class Project which is saved to file
this class has been shortened as the other fields are just Strings with getter and setter methods, they are saved correctly
*/
public class Project implements Serializable {
  public static int PAGE_COUNTER;           // Counts number of questions in project, Must start with page1

  private JList QPages = null;                            // List of all QPages to be saved to disk
  private static DefaultListModel QPagesListModel = null; // Access this to access JList
}

Ok, my problem is that when I call the save method, I don´t get a warning if the ListModel is empty, I have tried this with an empty on and I get no warning.
Now when I read the file in again and check the Project being read, I get the message that the istModel is empty.
P.S. the class QPage is also serialized and contains JLists, but these are not important yet, all I want is the List of QPage Objects to be read right.
Appreciate any help but don´t rack your brains about it, I will find a way around it next week.
Thanks a lot for the input so far.


------------

AAARRRGGGHHHHH!!! my indentation was lost!!!!!

[Drain]

Originally posted by scottfree
AAARRRGGGHHHHH!!! my indentation was lost!!!!!

[ code ] tags, bro.

There needs to be a sticky at the top of each programming forum that says "USE THE **** CODE TAGS WHEN YOU POST CODE," I swear.

[mikeBarr81]

you can edit what you posted to tidy it up if you want, theres an edit button at the bottom of each post. Simply enclose all the code in [code] tags as drain said (like html, [tag] to start and [/tag] to end).

[scottfree]

Thanks for the tip Drain.
Just a little confused as there was no CODE button to add the code tag, but now I know.

[cjard]

Originally posted by scottfree
there was no CODE button to add the code tag, but now I know.

that's because some dumbarse at jelsoft, decided to put a # symbol on it instead of the word CODE.. look nex t to the PHP button

[scottfree]

OK, so that is what it is for.
I have just been typing my own tags, it is easier and quicker.
Thanks for the tip.

[cjard]

Originally posted by scottfree
OK, so that is what it is for.
I have just been typing my own tags, it is easier and quicker.
Thanks for the tip.

i do that too, because, probably the same clever individual thought "i know.. let's prompt them for the text they want to CODE-***.. "

and they used a single line text box prompt..

hmm, now i dunno about you.. but i dont write lany programs on a single line...

lol, so yeah.. i write my code tags too.. if youre interested in syntax highlighting. like this:

public class CubbyHole {
  private int contents;
  private boolean available = false;


  public synchronized int get() {
    //while (available == false) {
      //try {
        // wait for Producer to put value
        //wait();
      //} catch (InterruptedException e) {
      //}
    //}
    available = false;
    // notify Producer that value has been retrieved
    //notifyAll();
    return contents;
  }
  public synchronized void put(int value) {
    //while (available == true) {
      //try {
        // wait for Consumer to get value
        //wait();
      //} catch (InterruptedException e) {
      //}
    //}
    contents = value;
    available = true;
    // notify Consumer that value has been set
    //notifyAll();
  }
}

let me know and i'll get a great util for you

[scottfree]

Yeah, that looks great.
Syntax highlighting rocks!
I use it all the time because I use Textpad to code mostly and then when I read code in a forum, it takes a little longer to find the important parts.
Thanks.