Prove this: "Serialization Is Not for Statics" in java?

Question

Prove this: 'Serialization Is Not for Statics' in java?With an example.

Vulpes · Answer

Consider this simple example: // Animal.java import java.io.*; public class Animal implements Serializable { public static int numberOfAnimals; public String name; public String type; public int age; public Animal(String name, String type, int age) { this.name = name; this.type = type; this.age = age; numberOfAnimals++; } public String toString() { return "Name = " + name + ", Type = " + type + ", Age = " + age; } public static void main(String[] args) { String filename = "animal.ser"; Animal a = new Animal("Leo", "Lion", 3); System.out.println("Number of animals before serialization is " + Animal.numberOfAnimals); // serialize the object to file FileOutputStream fos = null; ObjectOutputStream out = null; try { fos = new FileOutputStream(filename); out = new ObjectOutputStream(fos); out.writeObject(a); out.close(); } catch (Exception ex) { ex.printStackTrace(); } // now change the static field Animal.numberOfAnimals = 5; // deserialize the object from file FileInputStream fis = null; ObjectInputStream in = null; try { fis = new FileInputStream(filename); in = new ObjectInputStream(fis); a = (Animal)in.readObject(); in.close(); } catch (Exception ex) { ex.printStackTrace(); } System.out.println(a); System.out.println("Number of animals after deserialization is " + Animal.numberOfAnimals); } } When you compile and run this program the output is: Number of animals before serialization is 1 Name = Leo, Type = Lion, Age = 3 Number of animals after deserialization is 5 The value of the static field, numberOfAnimals, has changed from 1 to 5 because we set it to 5 after we'd serialized the object. As the original value of 1 has not been restored, this proves that static fields are not serialized.

Abhijeet Singh · Answer

Thank you sir.. :)

Prove this: "Serialization Is Not for Statics" in java?

Answers (2)