无法序列化JTree的根节点（groovy / java）

Question

I am working on a swing application which primarily includes a JTree and some other components in it. The complete logic behind the UI display is based upon the root node of JTree. It is a nested node with individual custom UserObjects set to each of the child nodes.

I need to preserve the state of my application for which the single nested root node of the JTree should be preserved. I am unable to do so.

class SerializeImpl implements Serializable{

    def doSerialize() throws Exception{
        def root = FeedTree.getInstance().getModel().getRoot()
        def object = new SerializableNode(top:root)
        ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream("new.txt"))
        out.writeObject(object)
    }

    def doDeSerialize(){
        def file = new File('new.txt')
        def serNodeObj
        try{        
            file.withObjectInputStream(getClass().classLoader){ ois ->
                ois.eachObject{ serNodeObj = it }
            }
            return serNodeObj.getValue()
        }
        catch(FileNotFoundException ex){
            return null
        }

    }       

}


class SerializableNode implements Serializable{

    def top

    def getValue(){
        return top
    }

}

class FeedTree extends JTree{

...............
a singleton instance
...............

}

The doSerialize() method is executed first followed by a System.exit(1) and followed by a fresh display of UI which does doDeSerialize() .. The doSerialize() method does write something onto the news.txt file but I am not sure if it is serializing the object corrrectly. Moreover the System.exit(1) after serializing doesn't work.

After a forced Exit (from eclipse console close) the first execution of doDeSerialize() throws the following exception.

Caught: java.io.WriteAbortedException: writing aborted; java.io.NotSerializableException: groovy.util.slurpersupport.NodeChildren
    at functionalities.SerializeImpl$_doDeSerialize_closure1.doCall(SerializeImpl.groovy:23)
    at functionalities.SerializeImpl.doDeSerialize(SerializeImpl.groovy:22)

I am unable to understand why the serialize is (probably) failing and why the System.exit(1) is not functioning correctly after the serialize. Please help.

Answer 1

In order for SerializableNode to actually be serializable, its whole object graph must be serializable. What type of value is top ? If that is not serializable, the node will thrown a NotSerializableException when writing.

If top cannot be made Serializable, then you should declare it as transient and implement writeResolve and readResolve to properly write/read the non serializable value.

Answer 2

look at method invokeLater or better for Serializable for invokeAndWait() , because Swing code must be done on Event Dispatch Thread,

correct way, create JTree with DefaultTreeModel separatelly, and from your Serializable methods just to add TreeNodes wrapped into invokeLater