Java ObjectInputStream reading from different Application

Question

I saved an ArrayList<MyClass> as object with an ObjectOutputStream. Now, how can I read that object on my another application project with a ObjectInputStream? I tried and it throws an ClassNotFoundException. I have copied MyClass from project 1 to project 2. Do I have to do anything else?

Answer 1

You should not copy a class and the expect that it looks the same - the Java Compiler / the JVM notices the changes. Use exactly the same class file!!!

There are several versions to do so:

• Deliver Project1 with Project2 and set up your CLASSPATH
• Copy the class file in the same package to Project2
• attach a Jar to Project2 containing MyClass

And what you never should forgett: Every Serializable should have a serialVersionUID Eclipse automatically makes a warning - click on it and generate it. If you don't have Eclipse, use serialver from the JDK.
But don't forget: If your class changed so that old versions won't be interpretable by new versions, change the serialversionUID.