Serialization with Externalizable

• Class implements Externalizable. Class has to implement writeExternal() and readExternal().
• We have to define our own implementation for serialization and deserialization process. Default implementation is not available(Unlike Serializable).
• During deserialization default constructor is used. Hence default constructor is must. Otherwise BOOOM.
• Serialization using Externalizable is little faster than Serializable.
• Super.writeExternal() needs to be executed for super class field’s serialization.

Example:- 

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public class Student implements Externalizable { private String name; public String getName() { return name; } public void setName(String name) { this.name = name; } @Override public void writeExternal(ObjectOutput out) throws IOException { out.writeObject(name); } @Override public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException { name = (String) in.readObject(); } } public class Serialize { public static void main(String[] args) throws FileNotFoundException, IOException { Student student = new Student(); student.setName("External"); ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream("student_ex.ser")); out.writeObject(student); out.close(); System.out.println("Serialization complete"); } } public class Deserialize { public static void main(String[] args) throws FileNotFoundException, IOException, ClassNotFoundException { ObjectInputStream in = new ObjectInputStream(new FileInputStream("student_ex.ser")); Student student = (Student) in.readObject(); in.close(); System.out.println(student.getName()); } }