SerializationCodeOct2021

package com.learn.java;

public class Main {

    public static void main(String[] args) {

        //case-1:   serializing a custom class that does not implement serializable interface
        ////OUTPUT - Got exception while doing serialization... : java.io.NotSerializableException: com.learn.java.Student

        //case-2:   serializing a custom class that  implement serializable interface, but no serialversionUID. Deserialize it . ( if JVM same then it will be success..
        // this can fail when client-server model with diff JVM implementation)
        // add a new field and try to deserialize the older serialized object. this will fail.

        //case-3: serializing a custom class that  implement serializable interface, and having serialversionUID. Deserialize it .
        // add a new field (private or public) ( dont change the serialVersionUID) and try to deserialize the older serialized object. this will succeed.

        //case-4: serializing a custom class that  implement serializable interface, and having serialversionUID. Deserialize it .
        // add a new field ( and change the serialVersionUID) and try to deserialize the older serialized object. this will FAIL.

        //case5: ArrayList of custom class that does not implement serializable
        //will it fail or succeed...
        //ArrayList of custom class that does not implement serializable , but without serialVersionUID
        //Document it..

        // case5: Arralist , Hashmap, etc - are they serializable.. yes..they are .. along with String, Integer etc
        //Document it. no need of  code as you know it..
        

    }
}

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----------1-----------------------------------------
----------------------------------------------------

package com.learn.java;

public class StudentOfCase1 {

    private String name;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

}
-----

*********

package com.learn.java;

import java.io.FileOutputStream;
import java.io.ObjectOutputStream;

//  //case-1:   serializing a custom class that does not implement serializable interface
//OUTPUT - Got exception while doing serialization... : java.io.NotSerializableException: com.learn.java.Student
public class SerializeCase1 {

    public static void main(String[] args) {

        StudentOfCase1 student = new StudentOfCase1();
        student.setName("paramu");

        try {
            FileOutputStream fos = new FileOutputStream("file1.text");
            ObjectOutputStream out = new ObjectOutputStream(fos);

            out.writeObject(student);
            out.flush();
            out.close();
            System.out.println("successfully serialized...");

        } catch (Exception ex) {
            System.out.println("Got exception while doing serialization... : " + ex);
        }
    }
}

----------------------------------------------------
----------2-----------------------------------------
----------------------------------------------------

package com.learn.java;

import java.io.Serializable;

public class StudentOfCase2 implements Serializable {

    private String name;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    //adding a new field for testing...
    private String id;

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

}

------------------------------------------------

package com.learn.java;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;

//case-2:   serializing a custom class that  implement serializable interface, but no serialversionUID.
//OUTPUT .. while trying to serialize ( without serialVersionUID) :: successfully serialized..

// Deserialize it . ( if JVM same then it will be success..
// this can fail when client-server model with diff JVM implementation)
// OUTPUT .. Name obtained after deserialziation: paramu
//successfully Deserialized...


// add a new field and try to deserialize the older serialized object. this will fail.
//OUTPUT: Got exception while doing DE-serialization... :
//               java.io.InvalidClassException: com.learn.java.StudentOfCase2; local class incompatible:
//                stream classdesc serialVersionUID = 2936280157816834217,
//                local class serialVersionUID = 5012959175663846953




public class SerializeCase2 {

    public static void main(String[] args) {

        StudentOfCase2 student = new StudentOfCase2();
        student.setName("paramu");

        try {
            FileOutputStream fos = new FileOutputStream("file1.text");
            ObjectOutputStream out = new ObjectOutputStream(fos);

            //SERIALIZE:
            out.writeObject(student);
            out.flush();
            out.close();
            System.out.println("successfully serialized...");

        } catch (Exception ex) {
            System.out.println("Got exception while doing serialization... : " + ex);
        }
    }
}

-----------------------------------

package com.learn.java;

import java.io.FileInputStream;
import java.io.ObjectInputStream;

public class DeserializeCase2 {

    public static void main(String[] args) {

        try {
            //DESERIALIZE:
            ObjectInputStream in = new ObjectInputStream(new FileInputStream("file1.text"));
            StudentOfCase2 student2 = (StudentOfCase2) in.readObject();
            System.out.println(" Name obtained after deserialziation: " +student2.getName());
            in.close();
            System.out.println("successfully Deserialized...");
        } catch (Exception ex) {
            System.out.println("Got exception while doing DE-serialization... : " + ex);
        }
    }
}


----------------------

----------------------------------------------------
----------3-----------------------------------------
----------------------------------------------------

package com.learn.java;

import java.io.Serializable;

public class StudentOfCase3 implements Serializable {

    private static final long serialVersionUID = 1L;

    private String name;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    //adding a new field for testing...
    private String id;

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

}

-------------------

package com.learn.java;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;

//case-3: serializing a custom class that  implement serializable interface, and having serialversionUID. Deserialize it .
// add a new field ( dont change the serialVersionUID) and try to deserialize the older serialized object. this will succeed.

//OUTPUT
    //successfully serialized...
//OUTPUT
    // Name obtained after deserialziation: paramu
    //successfully Deserialized...
//OUTPUT
    // Name obtained after deserialziation: paramu
    //successfully Deserialized...
//OUTPUT
    // Name obtained after deserialziation: paramu
    //     Name obtained after deserialziation: null
    //successfully Deserialized...
public class SerializeCase3 {

    public static void main(String[] args) {

        StudentOfCase3 student = new StudentOfCase3();
        student.setName("paramu");

        try {
            FileOutputStream fos = new FileOutputStream("file1.text");
            ObjectOutputStream out = new ObjectOutputStream(fos);

            //SERIALIZE:
            out.writeObject(student);
            out.flush();
            out.close();
            System.out.println("successfully serialized...");

        } catch (Exception ex) {
            System.out.println("Got exception while doing serialization... : " + ex);
        }
    }
}


---------------

package com.learn.java;

import java.io.FileInputStream;
import java.io.ObjectInputStream;

public class DeserializeCase3 {

    public static void main(String[] args) {

        try {
            //DESERIALIZE:
            ObjectInputStream in = new ObjectInputStream(new FileInputStream("file1.text"));
            StudentOfCase3 student3 = (StudentOfCase3) in.readObject();
            System.out.println(" Name obtained after deserialziation: " +student3.getName());
            System.out.println(" Name obtained after deserialziation: " +student3.getId());
            in.close();
            System.out.println("successfully Deserialized...");
        } catch (Exception ex) {
            System.out.println("Got exception while doing DE-serialization... : " + ex);
        }
    }
}


-----------

----------------------------------------------------
----------4-----------------------------------------
----------------------------------------------------

package com.learn.java;

import java.io.Serializable;

public class StudentOfCase4 implements Serializable {

    //changing the serialVersionUID from 2L to 3L for testing deserialization.
   // private static final long serialVersionUID = 2L;

    private static final long serialVersionUID = 3L; //adding a new field for testing...


    private String name;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

}

-----

package com.learn.java;

import java.io.FileOutputStream;
import java.io.ObjectOutputStream;

//case-4: serializing a custom class that  implement serializable interface, and having serialversionUID. Deserialize it .

//OUTPUT
    //successfully serialized...

// add a new field ( and change the serialVersionUID) and try to deserialize the older serialized object. this will FAIL.
//OUTPUT
    //Got exception while doing DE-serialization... : java.io.InvalidClassException: com.learn.java.StudentOfCase4;
    // local class incompatible: stream classdesc serialVersionUID = 2, local class serialVersionUID = 3

// Repeat without changing the serialVersionUID) and try to deserialize the older serialized object. this will also FAIL.
//OUTPUT
//Got exception while doing DE-serialization... : java.io.InvalidClassException: com.learn.java.StudentOfCase4;
// local class incompatible: stream classdesc serialVersionUID = 2, local class serialVersionUID = 3

public class SerializeCase4 {

    public static void main(String[] args) {

        StudentOfCase4 student = new StudentOfCase4();
        student.setName("paramu");

        try {
            FileOutputStream fos = new FileOutputStream("file1.text");
            ObjectOutputStream out = new ObjectOutputStream(fos);

            //SERIALIZE:
            out.writeObject(student);
            out.flush();
            out.close();
            System.out.println("successfully serialized...");

        } catch (Exception ex) {
            System.out.println("Got exception while doing serialization... : " + ex);
        }
    }
}

------

package com.learn.java;

import java.io.FileInputStream;
import java.io.ObjectInputStream;

public class DeserializeCase4 {

    public static void main(String[] args) {

        try {
            //DESERIALIZE:
            ObjectInputStream in = new ObjectInputStream(new FileInputStream("file1.text"));
            StudentOfCase4 student4 = (StudentOfCase4) in.readObject();
            System.out.println(" Name obtained after deserialziation: " +student4.getName());
        //    System.out.println(" Name obtained after deserialziation: " +student4.getId());
            in.close();
            System.out.println("successfully Deserialized...");
        } catch (Exception ex) {
            System.out.println("Got exception while doing DE-serialization... : " + ex);
        }
    }
}


---------------

----------------------------------------------------
----------5-----------------------------------------
----------------------------------------------------

package com.learn.java;

import java.io.Serializable;

public class Student implements Serializable {

    private String name;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

}

--------------

package com.learn.java;

import java.io.FileOutputStream;
import java.io.ObjectOutputStream;
import java.util.ArrayList;
import java.util.List;

//case5: ArrayList of custom class that does not implement serializable.
//Try to serialize it
//OUTPUT
// Got exception while doing serialization... : java.io.NotSerializableException: com.learn.java.Student

//Now Have the custom class implement Serializable and try serializing teh arraylist..
//OUTPUT
    //successfully serialized..

//Now De-serialize it
//OUTPUT
    // Name obtained after deserialziation: paramu
    //         successfully Deserialized...

public class SerializeCase5 {

    public static void main(String[] args) {

        Student student = new Student();
        student.setName("paramu");

        try {
            FileOutputStream fos = new FileOutputStream("studentData");
            ObjectOutputStream out = new ObjectOutputStream(fos);

            List<Student> studentList = new ArrayList<>();
            studentList.add(student);

            //SERIALIZE:
            out.writeObject(studentList);
            out.flush();
            out.close();
            System.out.println("successfully serialized...");

        } catch (Exception ex) {
            System.out.println("Got exception while doing serialization... : " + ex);
        }
    }
}


-------

package com.learn.java;

import java.io.FileInputStream;
import java.io.ObjectInputStream;
import java.util.ArrayList;
import java.util.List;

public class DeserializeCase5 {

    public static void main(String[] args) {
        ArrayList<Student>  studentList = new ArrayList<>(10);
        try {
            //DESERIALIZE:

            FileInputStream fis = new FileInputStream("studentData");
            ObjectInputStream in = new ObjectInputStream(fis);

            studentList = (ArrayList) in.readObject();

            System.out.println(" Name obtained after deserialziation: " +studentList.get(0).getName());
        //    System.out.println(" Name obtained after deserialziation: " +student4.getId());
            in.close();
            System.out.println("successfully Deserialized...");
        } catch (Exception ex) {
            System.out.println("Got exception while doing DE-serialization... : " + ex);
        }
    }
}

-------------