Re: NotSerializableException

From:
Eric Sosman <esosman@comcast-dot-net.invalid>
Newsgroups:
comp.lang.java.programmer
Date:
Tue, 14 Apr 2015 08:13:13 -0400
Message-ID:
<mgj073$od6$1@dont-email.me>
On 4/13/2015 9:51 PM, akkshaykhoslaa@gmail.com wrote:

Hi,

My code is as follows:

         File ser = new File("locationinstringform");
         FileInputStream fileIn3 = new FileInputStream(ser);
         ObjectInputStream objectIn3 = new ObjectInputStream(fileIn3);
         myObj = (MyObj) objectIn3.readObject();
         objectIn3.close();
         fileIn3.close();
         myObj.someFunction(x, y);
         FileOutputStream fileOut3 = new FileOutputStream(ser);
         ObjectOutputStream objectOut3 = new ObjectOutputStream(fileOut3);
         objectOut3.writeObject(myObj);
         objectOut3.close();
         fileOut3.close();

When I run my code, I get an error tracing to the line that says objectOut3.writeObject(myObj);

The error is as follows:
Exception in thread "main" java.io.NotSerializableException: java.util.HashMap$KeySet

However, that MyObj class I have defined isn't a HashMap or Set, and doesn't have a HashMap or Set. It only has 2 instance objects, one of which is one is an object I coded, and the other is an ArrayList. I have made sure all classes I have coded implement the serializable interface.

Any ideas as to why the problem could be arising and what the solution is? I have been stuck for a long time so any help would be much appreciated.


     Your object refers -- directly or indirectly -- to a HashMap.KeySet
instance. You mention an ArrayList: What does that list contain? Does
it, perhaps, hold a Set that turns out to be a HashMap.KeySet? Or does
it hold a Thing that refers to a Widget that refers to a Whatnot that
refers to a Gizmo that refers to a HashMap.KeySet?

     Serializing an object also serializes everything the object refers
to, and everything those objects refer to, and so on through the entire
object graph.

--
esosman@comcast-dot-net.invalid
"Don't be afraid of work. Make work afraid of you." -- TLM

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