Serialize GUI (Swing)

[Suletea Dorin]

Hy , i have the following issue :
I try to save a JFrame so it's layout and component locations are saved in a configuration file file.

public abstract class DockingFrame extends JFrame {
private final DockerEngine dockingEngine; //try to make transient
/**
* <b> Description </b><br>
*Creates new window
*/
protected DockingFrame() {
super();
dockingEngine=new DockerEngine(this);
setGlassPane(new DockingGlassPane()); // try to implement serializable
setContentPane(new JDesktopPane());
}

public class DockerEngine implements Runnable{
/** Is Dnd operation in course*/
private boolean dockingInProgress;
/** The thread of the engine*/
private Thread thisThread;
/** The window to witch the engine is associated with*/
private DockingFrame mainFrame;
/** Class used to catch the exceptions thrown by this class, can be overridden by user for custom exception handling
*/
private ExceptionCatcher exCatcher;
/** The docking component on witch the the dock operation will occur in case of drop*/
private DockingJPanel dropTarget;
/** The component to be droped*/
private Component dropContent;
/** Contains the tab name of the parent DockingTabbedPane, so it can be transfered to the drop target */
private String dropContentTabName;
/** Contains the data flavor of the component on witch the drop can occur in case of release, null if no data flavor specified*/
private String acceptableDataFlavorName;
/** Rectangle representing the approximately new position of the drop content in case of drop*/
private DockRectangle dockingRectangle;
/** The drop content will be less wide or tall than the parent by this ratio (depends on position, top or sides)*/
private final int DROPRATIO=4;
/**The flag that tells the engine if it needs to generate resize-able borders on the dnd components*/
private boolean generateBorders;

When i try to serialize that frame i get "NotSerializableException" on docker engine thou it's transient (isn't the point of transient to make fields not to be serialized?)

I did try to make that engine implement Serializable interface , then i get

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at javax.swing.plaf.basic.BasicTabbedPaneUI.paint(Unknown Source)
at javax.swing.plaf.ComponentUI.update(Unknown Source)
at javax.swing.JComponent.paintComponent(Unknown Source)
at srcp.ui.docking.DockingTabbedPane.paintComponent(DockingTabbedPane.java:425)

which i have no idea where comes from.

If you have other ideas about how to save that info , any suggestions are welcome.

Cheers mates ,
and Thanks

[Pierre Sugar]

DockerEngine is not marked as transient

[Suletea Dorin]

 

Pierre Sugar wrote:DockerEngine is not marked as transient

I removed it , but with a transient docker engine i get the

java.io.NotSerializableException: srcp.ui.docking.DockerEngine
at java.io.ObjectOutputStream.writeObject0(Unknown Source)

and

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at javax.swing.plaf.basic.BasicTabbedPaneUI.paint(Unknown Source)

ok , second exception i dont know it's source , but the first....
im not serializing it , why does it throw NotSerializableException maybe it's somehow related to the fact that i have a thread inside it (not plausible at all but this is the only thing that makes this class special :P )

[Martin Vashko]

I guess that the DockerEngine hooks itself somehow into the frame it is used with (most probably it registered itself as a listener somewhere). Even if you declare your reference as transient, it is being serialized due to other references deep in the structure of Swing objects.

[Suletea Dorin]

Interesting fact :

In my concrete case : BaseForm extends DockingFrame
DockingFrame extends JFrame implements Serializable
agregates DockerEngine


When i serialize new DockingFrame it works
When i serialize BaseForm it fails (like described above)

Any one got a clue why this is happening ?

[Prabakar Kalivaradan]

Hi,

Some Serialization basics:

1. Every serialized class should implement either Serializable or Externalizable
2. All non-static non-transient objects members reachable from saved object should be serializable
3. If a class doesn't implement Serializable or Externalizable directly (though its super class implements), any data member that is not serializable will result in NotSerializableException
4. Thread objects are not serializable and any reference by the saved object will cause NotSerializableException
5. Marking a non-serializable field as 'transient' for sure skips it during serialization and should not cause any issues
6. A class should not depend on super classes or subclasses for it's serialization to work properly. It has to take care of everything itself

So, unless you give us the complete source code of the class in question, we can't debug your issue.