Why does writeObject throw java io NotSerializableException and how do I fix it

Question

I have this exception and I don t understand why it would be thrown or  how I  should handle it   try       os writeObject element     catch  IOException e        e printStackTrace        Where element is a TransformGroup containing some other TransformGroups an instance of the class Atom   public class Atom extends Group implements Serializable      float pozX pozY      Group group  new Group           Color3f blue   new Color3f new Color 255        Color3f black   new Color3f new Color 0        Sphere AtSph new Sphere         public Atom final float WEIGHT  final int BOUNDS final float radius Color3f color                AppSetting ap  new AppSetting color  black           AtSph new Sphere radius 1 100 ap             The full error log   java io NotSerializableException  javax media j3d TransformGroup     at java io ObjectOutputStream writeObject0 Unknown Source      at java io ObjectOutputStream writeObject Unknown Source      at cls MolecularBuilder addAtom MolecularBuilder java 511      at cls MolecularBuilder Console HidrogenItemActionPerformed MolecularBuilder java 897      at cls MolecularBuilder Console 2 actionPerformed MolecularBuilder java 746      at javax swing AbstractButton fireActionPerformed Unknown Source      at javax swing AbstractButton Handler actionPerformed Unknown Source      at javax swing DefaultButtonModel fireActionPerformed Unknown Source      at javax swing DefaultButtonModel setPressed Unknown Source      at javax swing AbstractButton doClick Unknown Source      at javax swing plaf basic BasicMenuItemUI doClick Unknown Source      at javax swing plaf basic BasicMenuItemUI Handler mouseReleased Unknown Source      at java awt Component processMouseEvent Unknown Source      at javax swing JComponent processMouseEvent Unknown Source      at java awt Component processEvent Unknown Source      at java awt Container processEvent Unknown Source      at java awt Component dispatchEventImpl Unknown Source      at java awt Container dispatchEventImpl Unknown Source      at java awt Component dispatchEvent Unknown Source      at java awt LightweightDispatcher retargetMouseEvent Unknown Source      at java awt LightweightDispatcher processMouseEvent Unknown Source      at java awt LightweightDispatcher dispatchEvent Unknown Source      at java awt Container dispatchEventImpl Unknown Source      at java awt Window dispatchEventImpl Unknown Source      at java awt Component dispatchEvent Unknown Source      at java awt EventQueue dispatchEventImpl Unknown Source      at java awt EventQueue access 200 Unknown Source      at java awt EventQueue 3 run Unknown Source      at java awt EventQueue 3 run Unknown Source      at java security AccessController doPrivileged Native Method      at java security ProtectionDomain 1 doIntersectionPrivilege Unknown Source      at java security ProtectionDomain 1 doIntersectionPrivilege Unknown Source      at java awt EventQueue 4 run Unknown Source      at java awt EventQueue 4 run Unknown Source      at java security AccessController doPrivileged Native Method      at java security ProtectionDomain 1 doIntersectionPrivilege Unknown Source      at java awt EventQueue dispatchEvent Unknown Source      at java awt EventDispatchThread pumpOneEventForFilters Unknown Source      at java awt EventDispatchThread pumpEventsForFilter Unknown Source      at java awt EventDispatchThread pumpEventsForHierarchy Unknown Source      at java awt EventDispatchThread pumpEvents Unknown Source      at java awt EventDispatchThread pumpEvents Unknown Source      at java awt EventDispatchThread run Unknown Source    AppSetting  in Atom class  is just a custom class that extends Appearance

User · Accepted Answer

The fields of your object have in turn their fields, some of which do not implement Serializable. In your case the offending class is TransformGroup. How to solve it?

if the class is yours, make it Serializable
if the class is 3rd party, but you don't need it in the serialized form, mark the field as transient
if you need its data and it's third party, consider other means of serialization, like JSON, XML, BSON, MessagePack, etc. where you can get 3rd party objects serialized without modifying their definitions.

~ Answered on 2012-12-15 20:26:14

Why does writeObject throw java.io.NotSerializableException and how do I fix it?

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