Writing objects sequentially to a file with class ObjectOutputStream.

Description

Demo Code

import java.io.IOException;
import java.io.ObjectOutputStream;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.NoSuchElementException;
import java.util.Scanner;

public class Main
{
   private static ObjectOutputStream output; // outputs data to file

   public static void main(String[] args)
   {/*from   w  ww . ja va2 s. c  o m*/
      openFile();
      addRecords();
      closeFile();
   }

   // open file clients.ser
   public static void openFile()
   {
      try 
      {
         output = new ObjectOutputStream(
            Files.newOutputStream(Paths.get("clients.ser")));
      }
      catch (IOException ioException)
      {
         System.err.println("Error opening file. Terminating.");
         System.exit(1); // terminate the program
      } 
   } 

   // add records to file
   public static void addRecords()
   {
      Scanner input = new Scanner(System.in);

      System.out.printf("%s%n%s%n? ", 
         "Enter account number, first name, last name and balance.",
         "Enter end-of-file indicator to end input.");

      while (input.hasNext()) // loop until end-of-file indicator
      {
         try 
         {
            // create new record; this example assumes valid input
            Account record = new Account(input.nextInt(),
               input.next(), input.next(), input.nextDouble());

            // serialize record object into file
            output.writeObject(record); 
         } 
         catch (NoSuchElementException elementException)
         {
            System.err.println("Invalid input. Please try again.");
            input.nextLine(); // discard input so user can try again 
         } 
         catch (IOException ioException)
         {
            System.err.println("Error writing to file. Terminating.");
            break;
         } 

         System.out.print("? ");
      }
   } 

   // close file and terminate application 
   public static void closeFile() 
   {
      try 
      {
         if (output != null)
            output.close();
      } 
      catch (IOException ioException)
      {
         System.err.println("Error closing file. Terminating.");
      } 
   } 
}


class Account implements java.io.Serializable
{
   private int account;
   private String firstName;
   private String lastName;
   private double balance;
   
   // initializes an Account with default values
   public Account() 
   {
      this(0, "", "", 0.0); // call other constructor
   } 
  
   // initializes an Account with provided values
   public Account(int account, String firstName, 
      String lastName, double balance)
   {
      this.account = account;
      this.firstName = firstName;
      this.lastName = lastName;
      this.balance = balance;
   }

   // set account number   
   public void setAccount(int acct)
   {
      this.account = account;
   } 

   // get account number   
   public int getAccount() 
   { 
      return account; 
   } 
   
   // set first name   
   public void setFirstName(String firstName)
   {
      this.firstName = firstName;
   } 

   // get first name   
   public String getFirstName() 
   { 
      return firstName; 
   } 
   
   // set last name   
   public void setLastName(String lastName)
   {
      this.lastName = lastName;
   } 

   // get last name   
   public String getLastName() 
   {
      return lastName; 
   } 
   
   // set balance  
   public void setBalance(double balance)
   {
      this.balance = balance;
   } 

   // get balance   
   public double getBalance() 
   { 
      return balance; 
   } 
}
Writing objects sequentially to a file with class ObjectOutputStream. - Java File Path IO

Description

Demo Code

Result

Related Tutorials
