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Information Technology
03 Feb 2019

What is serialization and deserialization in java?

Java provides a mechanism which is  called object serialization where an object can be represented as a sequence or number of bytes that includes the object's data as well as information about the object's type and the types of data stored in the object.

After a serialized object has been written into a file, it can be read from the file and deserialized that is, the type information and bytes that represent the object and its data can be used to recreate the object in memory.

Most impressive is that the entire process is JVM independent, meaning an object can be serialized on one platform and deserialized on an entirely different platform.

Classes ObjectInputStream and ObjectOutputStream are high-level streams that contain the methods for serializing and deserializing an object.

The ObjectOutputStream class contains many write methods for writing various data types, but one method in particular stands out which is as follows,

public final void writeObject( Object a) throws IOException.

The above method serializes an Object and sends it to the output stream. Similarly, the ObjectInputStream class contains the following method for deserializing an object −

public final void readObject() throws IOException, ClassNotFoundException

This method retrieves the next Object out of the stream and deserializes it. The return value is Object, so you will need to cast it to its appropriate data type.

The ObjectOutputStream class is used to serialize an Object. 

Note − When serializing an object to a file, the standard convention in Java is to give the file a .ser extension.