Java ObjectOutputStream .writeFields ()

public void writeFields()   throws IOException

//w w  w .j av a2s .com
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.writeObject(person);
    
    outputStream.writeFields();

    outputStream.close();
  }
}