Use ObjectOutputStream to write the ArrayList object to a file called data bin

Serialization is a mechanism of converting the state of an object into a byte stream. Deserialization is the reverse process where the byte stream is used to recreate the actual Java object in memory. This mechanism is used to persist the object.

The byte stream created is platform independent. So, the object serialized on one platform can be deserialized on a different platform.

To make a Java object serializable we implement the java.io.Serializable interface.
The ObjectOutputStream class contains writeObject() method for serializing an Object.

public final void writeObject(Object obj)
                       throws IOException

The ObjectInputStream class contains readObject() method for deserializing an object.

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

Advantages of Serialization
1. To save/persist state of an object.
2. To travel an object across a network.

Only the objects of those classes can be serialized which are implementing java.io.Serializable interface.
Serializable is a marker interface (has no data member and method). It is used to “mark” java classes so that objects of these classes may get certain capability. Other examples of marker interfaces are:- Cloneable and Remote.

Points to remember
1. If a parent class has implemented Serializable interface then child class doesn’t need to implement it but vice-versa is not true.
2. Only non-static data members are saved via Serialization process.
3. Static data members and transient data members are not saved via Serialization process.So, if you don’t want to save value of a non-static data member then make it transient.
4. Constructor of object is never called when an object is deserialized.
5. Associated objects must be implementing Serializable interface.
Example :

class A implements Serializable{

// B also implements Serializable
// interface.
B ob=new B();  
}

SerialVersionUID
The Serialization runtime associates a version number with each Serializable class called a SerialVersionUID, which is used during Deserialization to verify that sender and receiver of a serialized object have loaded classes for that object which are compatible with respect to serialization. If the receiver has loaded a class for the object that has different UID than that of corresponding sender’s class, the Deserialization will result in an InvalidClassException. A Serializable class can declare its own UID explicitly by declaring a field name.
It must be static, final and of type long.
i.e- ANY-ACCESS-MODIFIER static final long serialVersionUID=42L;

If a serializable class doesn’t explicitly declare a serialVersionUID, then the serialization runtime will calculate a default one for that class based on various aspects of class, as described in Java Object Serialization Specification. However it is strongly recommended that all serializable classes explicitly declare serialVersionUID value, since its computation is highly sensitive to class details that may vary depending on compiler implementations, any change in class or using different id may affect the serialized data.

It is also recommended to use private modifier for UID since it is not useful as inherited member.

serialver
The serialver is a tool that comes with JDK. It is used to get serialVersionUID number for Java classes.
You can run the following command to get serialVersionUID

serialver [-classpath classpath] [-show] [classname…]

Example 1:

// Java code for serialization and deserialization 

// of a Java object

import java.io.*;

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

class A implements Serializable{

// B also implements Serializable
// interface.
B ob=new B();  
}

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

class A implements Serializable{

// B also implements Serializable
// interface.
B ob=new B();  
}

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

class A implements Serializable{

// B also implements Serializable
// interface.
B ob=new B();  
}

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

class A implements Serializable{

// B also implements Serializable
// interface.
B ob=new B();  
}

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

Object has been serialized
Data before Deserialization.
name = ab
age = 20
a = 2
b = 1000
Object has been deserialized
Data after Deserialization.
name = ab
age = 20
a = 0
b = 2000

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

Object has been serialized
Data before Deserialization.
name = ab
age = 20
a = 2
b = 1000
Object has been deserialized
Data after Deserialization.
name = ab
age = 20
a = 0
b = 2000

Object has been serialized
Data before Deserialization.
name = ab
age = 20
a = 2
b = 1000
Object has been deserialized
Data after Deserialization.
name = ab
age = 20
a = 0
b = 2000

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

class A implements Serializable{

// B also implements Serializable
// interface.
B ob=new B();  
}

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

// of a Java object5 

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

import2import3

import2import5// Java code for serialization and deserialization 5 import7

import2import9// Java code for serialization and deserialization 5 java.io.*;1

java.io.*;2 

import2java.io.*;4

import2java.io.*;6

java.io.*;2 

import2java.io.*;9

import2 1

java.io.*;2 

import2 4 5// of a Java object0

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

// of a Java object5 

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

import2 4

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

import2

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

import2

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

import2

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

java.io.*;2 

import2

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

import2

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

java.io.*;2 

import2

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

import2 1

java.io.*;2 

import2 4

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

import2 4

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

import2 4

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

// of a Java object5 

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

import2 4

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

// of a Java object5 

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

import2 4

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

Output :

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

Example 2:

// Java code for serialization and deserialization 

// of a Java object

import java.io.*;

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

Object has been serialized
Data before Deserialization.
name = ab
age = 20
a = 2
b = 1000
Object has been deserialized
Data after Deserialization.
name = ab
age = 20
a = 0
b = 2000

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

class A implements Serializable{

// B also implements Serializable
// interface.
B ob=new B();  
}

class A implements Serializable{

// B also implements Serializable
// interface.
B ob=new B();  
}

class A implements Serializable{

// B also implements Serializable
// interface.
B ob=new B();  
}

class A implements Serializable{

// B also implements Serializable
// interface.
B ob=new B();  
}

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

class A implements Serializable{

// B also implements Serializable
// interface.
B ob=new B();  
}

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

Object has been serialized
Data before Deserialization.
name = ab
age = 20
a = 2
b = 1000
Object has been deserialized
Data after Deserialization.
name = ab
age = 20
a = 0
b = 2000

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

class A implements Serializable{

// B also implements Serializable
// interface.
B ob=new B();  
}

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

class A implements Serializable{

// B also implements Serializable
// interface.
B ob=new B();  
}

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

class A implements Serializable{

// B also implements Serializable
// interface.
B ob=new B();  
}

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

class A implements Serializable{

// B also implements Serializable
// interface.
B ob=new B();  
}

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

class A implements Serializable{

// B also implements Serializable
// interface.
B ob=new B();  
}

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

class A implements Serializable{

// B also implements Serializable
// interface.
B ob=new B();  
}

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

class A implements Serializable{

// B also implements Serializable
// interface.
B ob=new B();  
}

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

class A implements Serializable{

// B also implements Serializable
// interface.
B ob=new B();  
}

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

class A implements Serializable{

// B also implements Serializable
// interface.
B ob=new B();  
}

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

class A implements Serializable{

// B also implements Serializable
// interface.
B ob=new B();  
}

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

class A implements Serializable{

// B also implements Serializable
// interface.
B ob=new B();  
}

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

Object has been serialized
Data before Deserialization.
name = ab
age = 20
a = 2
b = 1000
Object has been deserialized
Data after Deserialization.
name = ab
age = 20
a = 0
b = 2000

Object has been serialized
Data before Deserialization.
name = ab
age = 20
a = 2
b = 1000
Object has been deserialized
Data after Deserialization.
name = ab
age = 20
a = 0
b = 2000

class A implements Serializable{

// B also implements Serializable
// interface.
B ob=new B();  
}

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

class A implements Serializable{

// B also implements Serializable
// interface.
B ob=new B();  
}

class A implements Serializable{

// B also implements Serializable
// interface.
B ob=new B();  
}

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

class A implements Serializable{

// B also implements Serializable
// interface.
B ob=new B();  
}

class A implements Serializable{

// B also implements Serializable
// interface.
B ob=new B();  
}

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

Object has been serialized
Data before Deserialization.
name = ab
age = 20
a = 2
b = 1000
Object has been deserialized
Data after Deserialization.
name = ab
age = 20
a = 0
b = 2000

Object has been serialized
Data before Deserialization.
name = ab
age = 20
a = 2
b = 1000
Object has been deserialized
Data after Deserialization.
name = ab
age = 20
a = 0
b = 2000

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

public final Object readObject()
                  throws IOException,
               ClassNotFoundException

Object has been serialized
Object has been deserialized 
a = 1
b = geeksforgeeks

class A implements Serializable{

// B also implements Serializable
// interface.
B ob=new B();  
}

class A implements Serializable{

// B also implements Serializable
// interface.
B ob=new B();  
}

class A implements Serializable{

// B also implements Serializable
// interface.
B ob=new B();  
}

class A implements Serializable{

// B also implements Serializable
// interface.
B ob=new B();  
}

class A implements Serializable{

// B also implements Serializable
// interface.
B ob=new B();  
}

class A implements Serializable{

// B also implements Serializable
// interface.
B ob=new B();  
}