Error in serialization when file name is dynamic

Question

Hello there,
I am utilizing serialization functionality of Java to Save the work done using the application that I have developed. When the user goes to File -> Save, the application calls the following function:
public void save()
try{
System.out.println("before FOS");
FileOutputStream f_out = new FileOutputStream("*save.data*");
System.out.println("after FOS");
ObjectOutputStream out = new ObjectOutputStream (f_out);
System.out.println("after OOS");
out.writeObject(*myPanel*);
//myPanel is an instance of JPanel which contains all the sketches done by the user.
out.close();
f_out.close();
System.out.println("after writeObject");
catch(Exception e)
System.out.println("Exception in Save function");
This particular code runs fine but the problem is that the name of the serialized file is hard coded which is, "save.data" as highlighted in bold in the above code.
So I added the JFileChooser component to enable the user to type in the file name that he/she wants. The following is the amended code:
public void save()
JFileChooser chooserSave = new JFileChooser();
chooserSave.setCurrentDirectory(new File ("."));
returnVal2 = chooserSave.showSaveDialog(myPanel);
File fileName = chooserSave.getSelectedFile();
System.out.println("filename : " + fileName);
if(returnVal2 == JFileChooser.APPROVE_OPTION)
try{
System.out.println("before FOS");
FileOutputStream f_out = new FileOutputStream(fileName);
System.out.println("after FOS");
ObjectOutputStream out = new ObjectOutputStream (f_out);
System.out.println("after OOS");
out.writeObject(myPanel);
out.close();
f_out.close();
System.out.println("after writeObject");
catch(Exception e)
System.out.println("Exception in Save function");
With the amended code however, the programs throws exception after bold line which means writeObject method could not be performed.
Could anyone kindly advice what could be wrong? I have made almost all the possible amendments to the best of my knowledge but to no avail.
Thank you very much.
Note: This question has been posted earlier in java-forums.org @ http://www.java-forums.org/advanced-java/20147-serialization.html

Answer 1

You shouldn't Serialize swing components - draw the sketches to images or save them as their own objects and read them back in to populate the JPanel.
The reason you are suddenly getting the Exception is because the JFileChooser is referenced within the JPanel while you are saving it - and that particular partof the JFileChooser is not Serializable.
As was said before, you shouldn't Serialize swing components (the API specifies that swing serialized objects may not be compatible with future releases).