java.io.NotSerializableException

java.io.NotSerializableException is thrown when the object is not eligible for the serialization. We must implement the Serializable interface to make the class eligible for the serialization. This is a marker interface which tells the JVM that the class can be serialized.

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.ObjectOutputStream;

class Student {

      private String id;

      public String getId() {

            return id;

      }

      public void setId(String id) {

            this.id = id;

      }

}

public class NotSerializableExceptionTest {

      public static void main(String[] args) throws IOException{

            //Create FileOutputStream to create file

            FileOutputStream out = new FileOutputStream("student.dat");

            //Create ObjectOutputStream

            ObjectOutputStream outputStream = new ObjectOutputStream(out);

            //Create objects

            Student obj = new Student();

            obj.setId("001");

            //Write objects to stream

            outputStream.writeObject(obj);

            //Always close the stream

            outputStream.close();

      }

}

Output:

      Exception in thread "main" java.io.NotSerializableException: Student

      at java.io.ObjectOutputStream.writeObject0(Unknown Source)

      at java.io.ObjectOutputStream.writeObject(Unknown Source)

      at NotSerializableExceptionTest.main(NotSerializableExceptionTest.java:30)

How to fix java.io.NotSerializableException?

Student class must implement the serializable interface.