What is serialization and deserialization in Java POJO?

What is serialization and deserialization in Java POJO?

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Serialization and deserialization are fundamental concepts in Java programming, particularly when working with objects and data transmission over networks or storage in files. In this explanation, we'll focus on Java POJOs (Plain Old Java Objects), which are classes that contain only getter and setter methods for their instance variables.

What is Serialization?

Serialization is the process of converting an object's state into a format that can be written to a file, buffer, or network stream. In other words, it converts an object's data into a byte stream that represents its internal state. This allows you to persist an object's data or transmit it over a network.

In Java, serialization is achieved using the Serializable interface, which must be implemented by the class containing the data to be serialized. When an object implements Serializable, it means that the object can be converted into a byte stream and back again.

Here are some common scenarios where serialization is used:

What is Deserialization?

Deserialization is the reverse process of serialization – it converts a byte stream back into an object's original state. This process is also known as de-serializing or un-serializing.

When deserializing, Java reads the serialized byte stream and recreates the original object, restoring its internal state to the state it was in when the serialization occurred.

How Serialization and Deserialization Work with POJOs

To serialize a POJO, you need to follow these steps:

Here's a simple example:

public class Person implements Serializable {
private String name;
private int age;
public Person(String name, int age) {
this.name = name;
this.age = age;
}
// Getters and setters for name and age
}
// Serializing
Person person = new Person("John", 30);
ObjectOutputStream os = new ObjectOutputStream(new FileOutputStream("person.ser"));
os.writeObject(person);
// Deserializing
ObjectInputStream is = new ObjectInputStream(new FileInputStream("person.ser"));
Person deserializedPerson = (Person) is.readObject();

In this example, the Person class implements the Serializable interface. We create an instance of Person, serialize it using ObjectOutputStream, and then deserialize it back into a new object using ObjectInputStream.

Conclusion

Serialization and deserialization are essential concepts in Java programming, especially when working with objects. By implementing the Serializable interface and using ObjectOutputStream or ObjectInputStream, you can convert an object's state into a byte stream for storage or transmission over networks. This allows you to persist data, transmit it between systems, or create object clones.

I hope this explanation helps you understand serialization and deserialization with Java POJOs!

Why do we use serialization in Java?

In Java, serialization is a mechanism that allows an object to be converted into a byte stream, which can then be written to a file or transmitted over a network. This process of converting an object into a byte stream is called serializing the object. The reverse process, where a byte stream is converted back into an object, is called deserializing the object.

There are several reasons why we use serialization in Java:

When an object is serialized, its state (fields and their values) is captured and stored in the byte stream. The serialization process involves the following steps:

Java provides two ways of serialization:

In addition, Java also provides various APIs and libraries that provide additional support for serialization, such as:

In conclusion, serialization in Java is a powerful mechanism that allows us to efficiently store and transmit complex objects between different parts of a program or even across networks.