Re: NotSerializableException

From:

Robert Klemme <shortcutter@googlemail.com>

Newsgroups:

comp.lang.java.programmer

Date:

Tue, 14 Apr 2015 07:50:53 +0200

Message-ID:

<cp3o5uF7i2tU1@mid.individual.net>

On 14.04.2015 03:51, 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.

Obviously that assumption must be false: there must be a HashMap or sub
class of it somewhere in the graph of objects you are trying to
serialize. Since you seem to read it from a serialized stream
candidates to look closer are someFunction() as well as readResolve(),
readObject() and readObjectNoData() and their write counterparts. See

http://docs.oracle.com/javase/7/docs/api/java/io/Serializable.html

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.

Without seeing class MyObj and probably also super and sub classes it's
all only guessing.

Cheers

robert

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