JAVA EE: Java Tutorial : Java IO (Java Serialization with array or collection)

Tuesday, 4 October 2016

Java Tutorial : Java IO (Java Serialization with array or collection)

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Java Tutorial : Java IO (Java Serialization with array or collection)

Employee.java

import java.io.Serializable;

public class Employee implements Serializable
{
    private static final long serialVersionUID = 765764534241652904L;
    private int id;
    private String name;

    public Employee(int id, String name)
    {
        super();
        this.id = id;
        this.name = name;
    }

    public int getId()
    {
        return id;
    }

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

    public String getName()
    {
        return name;
    }

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

}

SerializationDemo.java

import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectOutputStream;
import java.util.ArrayList;

public class SerializationDemo
{

    public static void main(String[] args) throws FileNotFoundException,
            IOException, ClassNotFoundException
    {
        SerializationDemo serializationDemo = new SerializationDemo();
        serializationDemo.writeEmployeeObject();
    }

    private void writeEmployeeObject() throws FileNotFoundException,
            IOException
    {
        FileOutputStream fileOutputStream = null;
        ObjectOutputStream objectOutputStream = null;
        try
        {
            fileOutputStream = new FileOutputStream("employee.tmp");
            objectOutputStream = new ObjectOutputStream(fileOutputStream);

            Employee employee1 = new Employee(101, "Peter");
            Employee employee2 = new Employee(102, "Dave");
            Employee employee3 = new Employee(103, "Ram");

            ArrayList<Employee> listOfEmployees = new ArrayList<Employee>();
            listOfEmployees.add(employee1);
            listOfEmployees.add(employee2);
            listOfEmployees.add(employee3);

            /*
             * Write the specified object to the
             * ObjectOutputStream.
             */
            objectOutputStream.writeObject(listOfEmployees);
            System.out
                    .println("Successfully written list of employee objects to the file.\n");
        }
        finally
        {

            if (objectOutputStream != null)
            {
                /*
                 * Closing a ObjectOutputStream will also
                 * close the OutputStream instance to which
                 * the ObjectOutputStream is writing.
                 */
                objectOutputStream.close();
            }
        }

    }

}

Output

Successfully written list of employee objects to the file.

employee.tmp

DeSerializationDemo.java

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.util.ArrayList;

public class DeSerializationDemo
{

    public static void main(String[] args) throws FileNotFoundException,
            IOException, ClassNotFoundException
    {
        DeSerializationDemo deSerializationDemo = new DeSerializationDemo();
        deSerializationDemo.readEmployeeObject();
    }

    private void readEmployeeObject() throws IOException,
            FileNotFoundException, ClassNotFoundException
    {
        FileInputStream fileInputStream = null;
        ObjectInputStream objectInputStream = null;

        try
        {
            fileInputStream = new FileInputStream("employee.tmp");
            objectInputStream = new ObjectInputStream(fileInputStream);

            /*
             * Read an object from the ObjectInputStream.
             */
            ArrayList<Employee> listOfEmployees = (ArrayList<Employee>) objectInputStream
                                                                            .readObject();
            System.out
                    .println("Successfully read list of employee objects from the file.\n");

            for (Employee employee : listOfEmployees)
            {
                System.out.println("Id  = " + employee.getId());
                System.out.println("Name = " + employee.getName());
                System.out.println("--------------------------");
            }

        }
        finally
        {

            if (objectInputStream != null)
            {
                /*
                 * Closing a ObjectInputStream will also
                 * close the InputStream instance from which
                 * the ObjectInputStream is reading.
                 */
                objectInputStream.close();
            }
        }

    }

}

Output

Successfully read list of employee objects from the file.

Id  = 101
Name = Peter
--------------------------
Id  = 102
Name = Dave
--------------------------
Id  = 103
Name = Ram
--------------------------