Java tutorial
import java.io.FileOutputStream; import java.io.ObjectOutputStream; import java.io.Serializable; class Person implements Serializable { private String firstName; private String lastName; private int age; public Person() { } public String getFirstName() { return firstName; } public void setFirstName(String firstName) { this.firstName = firstName; } public String getLastName() { return lastName; } public void setLastName(String lastName) { this.lastName = lastName; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } public String toString() { StringBuffer buffer = new StringBuffer(); buffer.append(firstName); buffer.append("\n"); buffer.append(lastName); buffer.append("\n"); buffer.append(age); buffer.append("\n"); return buffer.toString(); } } public class Main { public static void main(String[] args) throws Exception { ObjectOutputStream outputStream = new ObjectOutputStream(new FileOutputStream("yourFile.dat")); Person person = new Person(); person.setFirstName("A"); person.setLastName("B"); person.setAge(38); outputStream.writeObject(person); person = new Person(); person.setFirstName("C"); person.setLastName("D"); person.setAge(22); outputStream.writeUnshared(person); outputStream.close(); } }