The Serializable interface in Java is a marker interface (i.e., it has no methods) that allows an object to be converted into a byte stream, which can then be saved to a file or sent over a network. It enables object persistence and object transfer.
To make a class serializable, it must:
- Implement
java.io.Serializable. - Ensure all non-transient fields are also serializable.
Simple Program: Serialize and Deserialize an Object
LotusJavaPrince wants to save Mahesh’s user profile data into a file and restore it later.
import java.io.*;
// Step 1: Make the class serializable
class UserProfile implements Serializable {
String name;
int age;
transient String password; // Won't be saved
public UserProfile(String name, int age, String password) {
this.name = name;
this.age = age;
this.password = password;
}
}
public class SimpleSerialization {
public static void main(String[] args) {
UserProfile user = new UserProfile("Mahesh", 30, "secret123");
// Serialization
try (ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("user.ser"))) {
oos.writeObject(user);
System.out.println("Object serialized.");
} catch (IOException e) {
e.printStackTrace();
}
// Deserialization
try (ObjectInputStream ois = new ObjectInputStream(new FileInputStream("user.ser"))) {
UserProfile deserializedUser = (UserProfile) ois.readObject();
System.out.println("Name: " + deserializedUser.name);
System.out.println("Age: " + deserializedUser.age);
System.out.println("Password: " + deserializedUser.password); // null (transient)
} catch (IOException | ClassNotFoundException e) {
e.printStackTrace();
}
}
}Output
Object serialized.
Name: Mahesh
Age: 30
Password: nullCode language: JavaScript (javascript)The Serializable interface enables Java objects to be saved and restored across JVM sessions or sent across systems — making it a cornerstone of persistence, networking, and distributed applications. With proper care, Serializable empowers systems like file backups, RMI, session storage, and object cloning.