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I have a quite complex Java object to serialize (which worked fine a couple of weeks ago). After having implemented a lot in the meantime, the serialization now fails throwing the following exception:
java.io.NotSerializableException: sun.java2d.SunGraphics2D
I have inspected all classes which seemed relevant, but could not find a field in any of them holding a Graphics2D type (or a similar type such as BufferedImage or the like). As I see it, the problem could also be that I'm using a class (from a library or so) which itself is serializable, but has a field of the unserializable type Graphics2D.
So, my question is: is there a "good" way to find the place where the serialization fails? Inspecting all classes and all changes made seems to be hardly feasible.
Thank you in advance
Lukas
PS. Here is the full stack trace of the exception:
java.io.NotSerializableException: sun.java2d.SunGraphics2D
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1184)
at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1548)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1509)
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
at java.io.ObjectOutputStream.writeArray(ObjectOutputStream.java:1378)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1174)
at java.io.ObjectOutputStream.access$300(ObjectOutputStream.java:162)
at java.io.ObjectOutputStream$PutFieldImpl.writeFields(ObjectOutputStream.java:1707)
at java.io.ObjectOutputStream.writeFields(ObjectOutputStream.java:482)
at java.awt.Container.writeObject(Container.java:3697)
at sun.reflect.GeneratedMethodAccessor17.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:483)
at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:988)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1496)
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
at java.io.ObjectOutputStream.writeArray(ObjectOutputStream.java:1378)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1174)
at java.io.ObjectOutputStream.access$300(ObjectOutputStream.java:162)
at java.io.ObjectOutputStream$PutFieldImpl.writeFields(ObjectOutputStream.java:1707)
at java.io.ObjectOutputStream.writeFields(ObjectOutputStream.java:482)
at java.awt.Container.writeObject(Container.java:3697)
at sun.reflect.GeneratedMethodAccessor17.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:483)
at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:988)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1496)
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
at java.io.ObjectOutputStream.writeArray(ObjectOutputStream.java:1378)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1174)
at java.io.ObjectOutputStream.access$300(ObjectOutputStream.java:162)
at java.io.ObjectOutputStream$PutFieldImpl.writeFields(ObjectOutputStream.java:1707)
at java.io.ObjectOutputStream.writeFields(ObjectOutputStream.java:482)
at java.awt.Container.writeObject(Container.java:3697)
at sun.reflect.GeneratedMethodAccessor17.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:483)
at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:988)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1496)
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
at java.io.ObjectOutputStream.writeArray(ObjectOutputStream.java:1378)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1174)
at java.io.ObjectOutputStream.access$300(ObjectOutputStream.java:162)
at java.io.ObjectOutputStream$PutFieldImpl.writeFields(ObjectOutputStream.java:1707)
at java.io.ObjectOutputStream.writeFields(ObjectOutputStream.java:482)
at java.awt.Container.writeObject(Container.java:3697)
at sun.reflect.GeneratedMethodAccessor17.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:483)
at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:988)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1496)
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:348)
at java.awt.Window.writeObject(Window.java:2943)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:483)
at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:988)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1496)
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:348)
at java.awt.AWTEventMulticaster.save(AWTEventMulticaster.java:946)
at java.awt.Window.writeObject(Window.java:2931)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:483)
at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:988)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1496)
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1548)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1509)
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1548)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1509)
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:348)
at java.util.LinkedList.writeObject(LinkedList.java:1131)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:483)
at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:988)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1496)
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1548)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1509)
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:348)
at eas.simulation.SerializableSimulationState.save(SerializableSimulationState.java:121)
at eas.plugins.standard.visualization.ControlPanel.actionPerformed(ControlPanel.java:202)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2346)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
at java.awt.Component.processMouseEvent(Component.java:6527)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
at java.awt.Component.processEvent(Component.java:6292)
at java.awt.Container.processEvent(Container.java:2234)
at java.awt.Component.dispatchEventImpl(Component.java:4883)
at java.awt.Container.dispatchEventImpl(Container.java:2292)
at java.awt.Component.dispatchEvent(Component.java:4705)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4898)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4533)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4462)
at java.awt.Container.dispatchEventImpl(Container.java:2278)
at java.awt.Component.dispatchEvent(Component.java:4705)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:746)
at java.awt.EventQueue.access$400(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:697)
at java.awt.EventQueue$3.run(EventQueue.java:691)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:86)
at java.awt.EventQueue$4.run(EventQueue.java:719)
at java.awt.EventQueue$4.run(EventQueue.java:717)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:716)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)
1000
Okay, inspired by the idea of Ben Lawry who, however, did not present an actual implementation, I have also programmed a class crawler which finds "unserializable fields", i.e., non-static, non-transient fields that are either not implementing the Serializable interface themselves or contain fields that are non-static, non-transient and do not implement the Serializable interface.
You can add several classes to be tested in the list in the main method (see comment). The output is a list of fields from these classes or any referenced classes that are not serializable by the above definition (which, however, is not exactly equal to the actually serializable fields, but captures a superset of the latter); for each field which itself does implement the Serializable interface, a list of fields referenced in the type of that field is given which cause the field being not serializable (if the list is empty the field itself does not implement the Serializable interface).
Here is the code, hope it helps others, too:
import java.io.Serializable;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedList;
import javax.swing.JComponent;
public class Crawler {
public static boolean crawlRecursively(Field field, HashSet<Class<?>> alreadyCrawled, HashMap<Field, HashSet<String>> badFields) {
if (alreadyCrawled.contains(field.getType())) {
return !badFields.keySet().contains(field);
}
alreadyCrawled.add(field.getType());
if (Modifier.isStatic(field.getModifiers())
|| Modifier.isTransient(field.getModifiers())
|| field.getType().isPrimitive()) {
return true;
} else if (Serializable.class.isAssignableFrom(field.getType())) {
boolean allGood = true;
for (Field f : field.getType().getDeclaredFields()) {
boolean isGood = crawlRecursively(f, alreadyCrawled, badFields);
if (!isGood) {
if (!badFields.containsKey(field)) {
badFields.put(field, new HashSet<>());
}
badFields.get(field).add(f.getType().getSimpleName() + " " + f.getName());
allGood = false;
}
}
return allGood;
} else {
if (!badFields.containsKey(field)) {
badFields.put(field, new HashSet<>());
}
return false;
}
}
public static HashMap<Field, HashSet<String>> initiateCrawling(Collection<Class<?>> roots) {
HashMap<Field, HashSet<String>> badFields = new HashMap<>();
for (Class<?> root : roots) {
for (Field f : root.getDeclaredFields()) {
crawlRecursively(f, new HashSet<>(), badFields);
}
}
return badFields;
}
public static void main(String[] args) {
LinkedList<Class<?>> roots = new LinkedList<>();
roots.add(JComponent.class); // ADD YOUR CLASSES HERE.
HashMap<Field, HashSet<String>> badFields = initiateCrawling(roots);
if (badFields.keySet().size() == 0) {
System.out.println("All fields are serializable (not having checked the given class(es) themselves).");
} else {
System.out.println("The following fields are not serializable in the class tree(s) given by " + roots + ":");
}
for (Field field : badFields.keySet()) {
System.out.println("<UnSer> "
+ field.getType().getSimpleName() + " "
+ field.getName() + " ("
+ field.getDeclaringClass().getName() + ") => " + badFields.get(field));
}
}
}
Example output for class JComponent:
The following fields are not serializable in the class tree(s) given by [class javax.swing.JComponent]:
<UnSer> Border border (javax.swing.JComponent) => []
<UnSer> ComponentInputMap windowInputMap (javax.swing.JComponent) => [JComponent component]
<UnSer> VetoableChangeSupport vetoableChangeSupport (javax.swing.JComponent) => [VetoableChangeListenerMap map, Object source]
<UnSer> SingleSelectionModel selectionModel (javax.swing.JPopupMenu) => []
<UnSer> JPopupMenu popupMenu (javax.swing.JComponent) => [SingleSelectionModel selectionModel]
<UnSer> Object source (java.beans.VetoableChangeSupport) => []
<UnSer> VetoableChangeListenerMap map (java.beans.VetoableChangeSupport) => []
<UnSer> JComponent component (javax.swing.ComponentInputMap) => [VetoableChangeSupport vetoableChangeSupport, JPopupMenu popupMenu, Border border, InputVerifier inputVerifier]
<UnSer> InputVerifier inputVerifier (javax.swing.JComponent) => []
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