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What are Static members and who do they belong to?

Static members/variables belong to the class and not the object. Hence, static members are called - "class members" and not instance/object variables.

One important point to understand is that the process of Serialization only saves the state of an object of a class, but the value of a static member of a class is not saved when an object is serialized.

Why the values of a static member of a class is not saved when an object is serialized?

Static member belong to its class and it is not a part of an object of its class, hence, when an object's state is saved by the process of Serialization, the values of a static member of a class is not saved and static member is not a part of the saved state of an object.

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Let's understand this by an example -:

In the upcoming example, we will show you how the process of serialization and deserialization only saves the state of an object of a class, and it does not save the state of a static member of a class, because the static member only belongs to its class and not its object.

//Java - Static in Serialization Example


import java.io.*;

class StaticSerial implements Serializable
{
// static int(class member), belong to the class and not object
static int i =100;	

public static void main(String... ar)
{
	StaticSerial ob= new StaticSerial();
	System.out.println("At the time of Serialization, static member has value : " + i);
	try
	{
		//Serialization
		FileOutputStream fos= new FileOutputStream("E:\\File.ser"); //Writing saved state of the object in this file
		ObjectOutputStream oos= new ObjectOutputStream(fos);
		oos.writeObject(ob);	//Serializing, i.e. saving the state of this object, ob
		oos.close();
	
		//The value of static member is changed to 99
		i=99;	

		//Deserialization
		FileInputStream fis= new FileInputStream("E:\\File.ser");	//Reading the same file for Deserialization
		ObjectInputStream ois= new ObjectInputStream(fis);
		ob=(StaticSerial)ois.readObject();	//Deserializing, i.e. restoring the object to its original state.
		ois.close();
		System.out.println("After Deserialization, static member has value : "+ i);
	}
	catch(Exception e)
	{
		System.out.println(e);
	}
} //main method ends

} //class definition ends

Output is -:

At the time of Serialization, static member has value : 100
After Deserialization, static member has value : 99

Program Analysis

• In this code above, we are performing Serialization and Deserialization of an object.
• Our class has a static member of type int, with the value 100, when an object of this class was serialized.
• After this object was serialized, we changed the value of the static member to 99.
• When this object is deserialized, the value of static member is not restored to its original value of 100(the value when the object was serialized), because the static member belong to its class and not the object.
• This proves that the process of serialization and deserialization only works on the object of a class and it doesn't affect a static member of a class, and therefore, when object was deserialized, the value of static member is found to be 99 and not 100.

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