![]() JAVA SERIALIZATION DATA VERSION 5 HOW TOHow to Generate serialVersionUID?Īs per the documentation, each serialVersionUID field must be static, final, and of type long. ![]() If the reader doesn't have the newest version of the class, an InvalidClassException will be thrown. The serialized version will thus have an updated UID which will be stored together with the object and delivered to the reader. JAVA SERIALIZATION DATA VERSION 5 UPDATEIn case an update indeed needs to be made to the class, this can be denoted by incrementing the value of the serialVersionUID. It is used to verify that both "versions" of an object (at the sender's and the receiver's side) are compatible, i.e. ![]() That's precisely the reason why the serialVersionUID exists and is typically used with all serializable objects. This could have annoying consequences at best, and complete disarray of the business logic at worst. deserialization), the reader could load the "new" object into the "old" representation. ![]() Otherwise, it could happen, for example, that a change was made to the class of an object before its serialization which the receiver isn't aware of. There should be some mechanism of determining whether the object that was sent matches the object that was received. If we think about this, it makes much sense. The purpose of this value is to make sure that the classes used both by the sender (the one that serializes) and the receiver (the one that deserializes) of the serialized object are compatible with each other. What is the serialVersionUID?įor serialization and deserialization to work properly, each serializable class must have a version number associated with it - the serialVersionUID. "Serializability of a class is enabled by the class implementing the java.io.Serializable interface*. In the words of the Serializable Javadoc: Without a class implementing this interface, it's not possible to either serialize or deserialize objects from that class. The Serializable interface is used to "mark" classes which can be (de)serialized. its class) implements the Serializable interface. from a file or a socket) and converts it back into a Java object that lives inside the JVM.īefore either serialization or deserialization can be performed on an object, it is necessary that this object (i.e. It takes the byte-stream representation of an object (e.g. transferred through a network socket.ĭeserialization is the process opposite to serialization. How exactly does serialization work is beyond the scope of this article, but in general - it works by converting the object into a byte stream which can then be used as any other stream of information, e.g. Serialization is the process of storing the state of an object so that it can be persisted into a database, transferred over the network, written into a file, etc. Afterwards, we'll dive deeper into serialVersionUID and show what it is and how it works.įinally, we'll conclude by showing an example which should tie everything together. Although sometimes considered as " part of the black magic of the Java serialization API", in this article we'll see that serialVersionUID is in fact quite straightforward and simple.įirst, we'll gloss over serialization and deserialization to recollect some important ideas that we're going to need later on. ![]() In this article, we'll discuss a concept related to serialization and deserialization in Java. ![]()
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