Difference between FileInputStream and DataInputStream

Hai everyone,
I want to know the difference between FileInputStream and DataInutStream.As i am new to this environment i am little bit confused between the two. So i request you to explain the difference with an example so that everything will be clear for me.

FileInputStream is for reading bytes from a file, as is indicated in the API docs: http://java.sun.com/j2se/1.5.0/docs/api/java/io/FileInputStream.html
DataInputStream is for reading java primitives (byte, char, short, int, long, float, double, boolean) through some other stream, as is indicated in the API docs: http://java.sun.com/j2se/1.5.0/docs/api/java/io/DataInputStream.html
If you want to read Java primtives from a file, you'd use them together: FileInputStream fis = new FileInputStream("somefile"); // for reading bytes from the file
DataInputSeam dis = new DataInputStream(fis); // for interpreting bytes read by fis as Java primitives
int ii = dis.readInt(); // dis uses fis to read 4 bytes from the file, and interprets them as a Java int You should probably go through this: http://java.sun.com/docs/books/tutorial/essential/io/index.html

Similar Messages

Differences between awt and swing

Ive written the following code, however Ive implemented the gui in awt rather then swing. Ive been told it hs too be in swing. What is the difference between swing and awt what will I need to change in my program so that its done using swing rather then the awt? Heres the code:
// pp.java
// Grant Brown
// 22/02/02
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.util.*;
import javax.swing.*;
// =========================================================
// Class: pp
// This class drives the customer manager. It contains the
// main method which gets called as soon as this application
// begins to run.
// =========================================================
class pp extends Frame implements ActionListener
// Container of customer objects
private Vector customers = new Vector (100);
// List of names component. (Must specify java.awt in
// front of List to distinguish the List class in the
// java.awt package from the List class in the java.util
// package.)
private java.awt.List names = new java.awt.List ();
// Delete and update button components.
private Button delete;
private Button update;
// Default constructor.
public pp ()
// Assign "Paper Round Manager" to title bar of frame window.
super ("Paper Round Manager");
// Add a listener that responds to window closing
// events. When this event occurs (by clicking on the
// close box in the title bar), save customers and exit.
addWindowListener (new WindowAdapter ()
public void windowClosing
(WindowEvent e)
saveCustomers ();
System.exit (0);
// Place an empty label in the north part of the frame
// window. This is done to correct an AWT positioning
// problem.
Label l = new Label ();
add ("North", l);
// Place the names component in the center part of the
// frame window.
add ("Center", names);
// Create a panel object to hold four buttons.
Panel p = new Panel ();
Button b;
// Add an Insert button to the Panel object and register
// the current pp object as a listener for button events.
p.add (b = new Button ("Insert"));
b.addActionListener (this);
// Add a Delete button to the Panel object and register
// the current pp object as a listener for button events.
p.add (delete = new Button ("Delete"));
delete.addActionListener (this);
// The Delete button should be disabled until there is at
// least one customer to delete.
delete.setEnabled (false);
// Add an Update button to the Panel object and register
// the current pp object as a listener for button events.
p.add (update = new Button ("Update"));
update.addActionListener (this);
// The Update button should be disabled until there is at
// least one customer to update.
update.setEnabled (false);
// Add a Finish button to the Panel object and register
// the current customer object as a listener for button events.
p.add (b = new Button ("Finish"));
b.addActionListener (this);
// Add the panel object to the frame window container.
add ("South", p);
// Set the background of the frame window container to
// lightGray
setBackground (Color.lightGray);
// Set the size of the frame window container to 400
// pixels horizontally by 200 pixels vertically.
setSize (400, 200);
// Allow the user to resize the frame window.
setResizable (true);
// Load all contacts.
loadCustomers ();
// Make sure that the frame window is visible.
setVisible (true);
public void actionPerformed (ActionEvent e)
if (e.getActionCommand ().equals ("Delete"))
delete ();
else
if (e.getActionCommand ().equals ("Finish"))
saveCustomers ();
System.exit (0);
else
if (e.getActionCommand ().equals ("Insert"))
insert ();
else
update ();
public Insets getInsets ()
// Return an Insets object that describes the number of
// pixels to reserve as a border around the edges of the
// frame window.
return new Insets (10, 10, 10, 10);
public static void main (String [] args)
// Create a new pp object and let it do its thing.
new pp ();
private void delete ()
// Obtain index of selected contact item from the names
// component.
int index = names.getSelectedIndex ();
// If no item was selected, index is -1. We cannot update
// a contact if no contact item in the names component was
// selected - because we would have nothing to work with.
if (index != -1)
// Remove the contact item from the names component.
names.remove (index);
// Remove the Customer object from the contacts Vector
// object.
customers.remove (index);
// If there are no more customers ...
if (customers.size () == 0)
delete.setEnabled (false);
update.setEnabled (false);
else
// Make sure that the first contact item in the names
// list is highlighted.
names.select (0);
private void insert ()
// Create an Insert data entry form to enter information
// for a new customer.
DataEntryForm def = new DataEntryForm (this, "Insert");
// If the bOk Boolean flag is set, this indicates the user
// exited the form by pressing the Ok button.
if (def.bOk)
// Create a Contact object and assign information from
// the form to its fields.
Customer temp = new Customer ();
temp.name = new String (def.name.getText ());
temp.publication = new String (def.publication.getText ());
temp.round = new String (def.round.getText ());
temp.address = new String (def.address.getText ());
temp.phone = new String (def.phone.getText ());
// Add a new customer item to the names component.
names.add (temp.name + ", " + temp.publication);
// Add the Customer object to the contacts Vector
// object.
customers.add (temp);
// Make sure that the Delete and Update buttons are
// enabled.
delete.setEnabled (true);
update.setEnabled (true);
// Destroy the dialouge box.
def.dispose ();
// Make sure that the first customer item in the names list
// is highlighted.
names.select (0);
// ===========================================================
// Load all contacts from contacts.dat into the contacts
// Vector object. Also, make sure that the last name/first
// name from each contact is combined into a String object and
// inserted into the names component - as a contact item.
// ===========================================================
private void loadCustomers ()
FileInputStream fis = null;
try
fis = new FileInputStream ("Customers.dat");
DataInputStream dis = new DataInputStream (fis);
int nCustomers = dis.readInt ();
for (int i = 0; i < nCustomers; i++)
Customer temp = new Customer ();
temp.name = dis.readUTF ();
temp.publication = dis.readUTF ();
temp.round = dis.readUTF ();
temp.address = dis.readUTF ();
temp.phone = dis.readUTF ();
names.add (temp.name + ", " + temp.publication);
customers.add (temp);
if (nCustomers > 0)
delete.setEnabled (true);
update.setEnabled (true);
catch (IOException e)
finally
if (fis != null)
try
fis.close ();
catch (IOException e) {}
// Make sure that the first contact item in the names list
// is highlighted.
names.select (0);
// ========================================================
// Save all Customer objects from the customer Vector object
// to customer.dat. The number of customerss are saved as an
// int to make it easy for loadCustomers () to do its job.
// ========================================================
private void saveCustomers ()
FileOutputStream fos = null;
try
fos = new FileOutputStream ("customers.dat");
DataOutputStream dos = new DataOutputStream (fos);
dos.writeInt (customers.size ());
for (int i = 0; i < customers.size (); i++)
Customer temp = (Customer) customers.elementAt (i);
dos.writeUTF (temp.name);
dos.writeUTF (temp.publication);
dos.writeUTF (temp.round);
dos.writeUTF (temp.address);
dos.writeUTF (temp.phone);
catch (IOException e)
MsgBox mb = new MsgBox (this, "PP Error",
e.toString ());
mb.dispose ();
finally
if (fos != null)
try
fos.close ();
catch (IOException e) {}
private void update ()
// Obtain index of selected customer item from the names
// component.
int index = names.getSelectedIndex ();
// If no item was selected, index is -1. We cannot update
// a customer if no customer item in the names component was
// selected - because we would have nothing to work with.
if (index != -1)
// Obtain a reference to the customer object (from the
// customers Vector object) that is associated with the
// index.
Customer temp = (Customer) customers.elementAt (index);
// Create and display an update entry form.
DataEntryForm def = new DataEntryForm (this, "Update",
temp.name,
temp.publication,
temp.round,
temp.address,
temp.phone);
// If the user pressed Ok...
if (def.bOk)
// Update the customer information in the customers
// Vector object.
temp.name = new String (def.name.getText ());
temp.publication = new String (def.publication.getText ());
temp.round = new String (def.round.getText ());
temp.address = new String (def.address.getText ());
temp.phone = new String (def.phone.getText ());
// Make sure the screen reflects the update.
names.replaceItem (temp.name + ", " + temp.publication,
index);
// Destroy the dialouge box.
def.dispose ();
// Make sure that the first customer item in the names
// list is highlighted.
names.select (0);

Ive doen pretty much what you said burt now my program isnt working at all. The window comes up but instead of doing something when you click the button it just throws shit loads of exceptions. Heres my abridged code
// pp.java
// Grant Brown
// 22/02/02
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.util.*;
import javax.swing.*;
// =========================================================
// Class:PP
// This class drives the Paper Round manager. It contains the
// main method which gets called as soon as this application
// begins to run.
// =========================================================
class pp extends JFrame implements ActionListener
// Container of customer objects (one object per customer)
private Vector customers = new Vector (100);
// List of names component. (Must specify java.awt in
// front of List to distinguish the List class in the
// java.awt package from the List class in the java.util
// package.)
private java.awt.List names = new java.awt.List ();
// Delete and update button components.
private JButton delete;
private JButton update;
// Default constructor.
public pp ()
// Assign Contact Manager to title bar of frame window.
super ("Paper Round Manager");
// Add a listener that responds to window closing
// events. When this event occurs (by clicking on the
// close box in the title bar), save contacts and exit.
addWindowListener (new WindowAdapter ()
public void windowClosing
(WindowEvent e)
saveCustomers ();
System.exit (0);
// Place an empty label in the north part of the frame
// window. This is done to correct an AWT positioning
// problem. (One thing that you'll come to realize as
// you work with the AWT is that there are lots of bugs.)
JLabel l = new JLabel ();
getContentPane().add ("North", l);
// Place the names component in the center part of the
// frame window.
getContentPane().add ("Center", names);
// Create a panel object to hold four buttons.
JPanel p = new JPanel ();
JButton b;
// Add an Insert button to the Panel object and register
// the current cm object as a listener for button events.
p.add (b = new JButton ("Insert"));
b.addActionListener (this);
// Add a Delete button to the Panel object and register
// the current cm object as a listener for button events.
p.add (delete = new JButton ("Delete"));
delete.addActionListener (this);
// The Delete button should be disabled until there is at
// least one contact to delete.
delete.setEnabled (false);
// Add an Update button to the Panel object and register
// the current cm object as a listener for button events.
p.add (update = new JButton ("Update"));
update.addActionListener (this);
// The Update button should be disabled until there is at
// least one contact to update.
update.setEnabled (false);
// Add a Finish button to the Panel object and register
// the current cm object as a listener for button events.
p.add (b = new JButton ("Finish"));
b.addActionListener (this);
// Add the panel object to the frame window container.
getContentPane().add ("South", p);
// Set the background of the frame window container to
// lightGray (to give a pleasing effect).
setBackground (Color.lightGray);
// Set the size of the frame window container to 400
// pixels horizontally by 200 pixels vertically.
setBounds (50, 100, 400, 200);
// Do not allow the user to resize the frame window.
loadCustomers ();
// Load all contacts.
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// Make sure that the frame window is visible.
setVisible (true);
public void actionPerformed (ActionEvent e)
if (e.getActionCommand ().equals ("Delete"))
delete ();
else
if (e.getActionCommand ().equals ("Finish"))
saveCustomers ();
System.exit (0);
else
if (e.getActionCommand ().equals ("Insert"))
insert ();
else
update ();
public Insets getInsets ()
// Return an Insets object that describes the number of
// pixels to reserve as a border around the edges of the
// frame window.
return new Insets (10, 10, 10, 10);
public static void main (String [] args)
// Create a new cm object and let it do its thing.
new pp ();
private void delete ()
// Obtain index of selected customer item from the names
// component.
int index = names.getSelectedIndex ();
// If no item was selected, index is -1. We cannot update
// a contact if no contact item in the names component was
// selected - because we would have nothing to work with.
if (index != -1)
// Remove the customer item from the names component.
names.remove (index);
// Remove the Customer object from the contacts Vector
// object.
customers.remove (index);
// If there are no more customers ...
if (customers.size () == 0)
delete.setEnabled (false);
update.setEnabled (false);
else
// Make sure that the first contact item in the names
// list is highlighted.
names.select (0);
private void insert ()
// Create an Insert data entry form to enter information
// for a new contact.
DataEntryForm def = new DataEntryForm (this, "Insert");
// If the bOk Boolean flag is set, this indicates the user
// exited the form by pressing the Ok button.
if (def.bOk)
// Create a Customer object and assign information from
// the form to its fields.
Customer temp = new Customer ();
temp.name = new String (def.name.getText ());
temp.publication = new String (def.publication.getText ());
temp.address = new String (def.address.getText ());
temp.round = new String (def.round.getText ());
temp.phone = new String
(def.phone.getText ());
// Add a new customer item to the names component.
names.add (temp.publication + ", " + temp.address);
// Add the Customer object to the contacts Vector
// object.
customers.add (temp);
// Make sure that the Delete and Update buttons are
// enabled.
delete.setEnabled (true);
update.setEnabled (true);
// Destroy the dialog box.
def.dispose ();
// Make sure that the first customer item in the names list
// is highlighted.
names.select (0);
// ===========================================================
// Load all customers from customers.dat into the customers
// Vector object. Also, make sure that the last name/first
// name from each contact is combined into a String object and
// inserted into the names component - as a contact item.
// ===========================================================
private void loadCustomers ()
FileInputStream fis = null;
try
fis = new FileInputStream ("customers.dat");
DataInputStream dis = new DataInputStream (fis);
int nCustomers = dis.readInt ();
for (int i = 0; i < nCustomers; i++)
Customer temp = new Customer ();
temp.name = dis.readUTF ();
temp.publication = dis.readUTF ();
temp.address = dis.readUTF ();
temp.round = dis.readUTF ();
temp.phone = dis.readUTF ();
names.add (temp.publication + ", " + temp.address);
customers.add (temp);
if (nCustomers > 0)
delete.setEnabled (true);
update.setEnabled (true);
catch (IOException e)
finally
if (fis != null)
try
fis.close ();
catch (IOException e) {}
// Make sure that the first customer item in the names list
// is highlighted.
names.select (0);
// ========================================================
// Save all customer objects from the contacts Vector object
// to customers.dat. The number of contacts are saved as an
// int to make it easy for loadCustomers () to do its job.
// ========================================================
private void saveCustomers ()
FileOutputStream fos = null;
try
fos = new FileOutputStream ("customers.dat");
DataOutputStream dos = new DataOutputStream (fos);
dos.writeInt (customers.size ());
for (int i = 0; i < customers.size (); i++)
Customer temp = (Customer) customers.elementAt (i);
dos.writeUTF (temp.name);
dos.writeUTF (temp.publication);
dos.writeUTF (temp.address);
dos.writeUTF (temp.round);
dos.writeUTF (temp.phone);
catch (IOException e)
MsgBox mb = new MsgBox (this, "PP Error",
e.toString ());
mb.dispose ();
finally
if (fos != null)
try
fos.close ();
catch (IOException e) {}
private void update ()
// Obtain index of selected customer item from the names
// component.
int index = names.getSelectedIndex ();
// If no item was selected, index is -1. We cannot update
// a customer if no customer item in the names component was
// selected - because we would have nothing to work with.
if (index != -1)
// Obtain a reference to the Customer object (from the
// customer Vector object) that is associated with the
// index.
Customer temp = (Customer) customers.elementAt (index);
// Create and display an update entry form.
DataEntryForm def = new DataEntryForm (this, "Update",
temp.name,
temp.publication,
temp.address,
temp.round,
temp.phone);
// If the user pressed Ok...
if (def.bOk)
// Update the customer information in the customers
// Vector object.
temp.name = new String (def.name.getText ());
temp.publication = new String (def.publication.getText ());
temp.address = new String (def.address.getText ());
temp.round = new String (def.round.getText ());
temp.phone = new String (def.phone.getText ());
// Make sure the screen reflects the update.
names.replaceItem (temp.publication + ", " + temp.address,
index);
// Destroy the dialog box.
def.dispose ();
// Make sure that the first customer item in the names
// list is highlighted.
names.select (0);
// ========================================================
// Class: Customer
// This class describes the contents of a business customer.
// ========================================================
class Customer
public String name;
public String publication;
public String address;
public String round;
public String phone;
// ==========================================================
// Class: DataEntryForm
// This class provides a data entry form for entering customer
// information.
// ==========================================================
class DataEntryForm extends JDialog implements ActionListener
// bOk is a boolean flag. When true, it indicates that
// the Ok button was pressed to terminate the dialog box
// (as opposed to the Cancel button).
public boolean bOk;
// The following components hold the text that the user
// entered into the visible text fields.
public JTextField name;
public JTextField publication;
public JTextField address;
public JTextField round;
public JTextField phone;
public void actionPerformed (ActionEvent e)
// If the user pressed the Ok button, indicate this
// by assigning true to bOk.
if (e.getActionCommand ().equals ("Ok"))
bOk = true;
// Destroy the dialog box and return to the point
// just after the creation of the DataEntryForm object.
dispose ();
public DataEntryForm (JFrame parent, String title)
// Call the other constructor. The current constructor
// is used for insert operations. The other constructor
// is used for update operations.
this (parent, title, "", "", "", "", "");
public DataEntryForm (JFrame parent, String title,
String name, String publication,
String address, String round,
String phone)
// Initialize the superclass layer.
super (parent, title, true);
// Choose a grid bag layout so that components can be more
// accurately positioned. (It looks nicer.)
setLayout (new GridBagLayout ());
// Add appropriate first name, last name, phone, fax, and
// email components to the current DataEntryForm container.
// (Remember, DataEntryForm is a subclass of Dialog.
// Dialog is a container. Therefore, DataEntryForm
// inherits the ability to be a container.)
addComponent (this, new JLabel ("Name: "), 0, 0, 1, 1,
GridBagConstraints.NONE,
GridBagConstraints.WEST);
this.name = new JTextField (15);
addComponent (this, this.name, 1, 0, 1, 1,
GridBagConstraints.NONE,
GridBagConstraints.CENTER);
if (title.equals ("Update"))
this.name.setText (name);
addComponent (this, new JLabel ("Publications: "), 0, 1, 1, 1,
GridBagConstraints.NONE,
GridBagConstraints.WEST);
this.publication = new JTextField (15);
addComponent (this, this.publication, 1, 1, 1, 1,
GridBagConstraints.NONE,
GridBagConstraints.CENTER);
if (title.equals ("Update"))
this.publication.setText (publication);
addComponent (this, new JLabel ("Address "), 0, 2, 1, 1,
GridBagConstraints.NONE,
GridBagConstraints.WEST);
this.address = new JTextField (15);
addComponent (this, this.address, 1, 2, 1, 1,
GridBagConstraints.NONE,
GridBagConstraints.CENTER);
if (title.equals ("Update"))
this.address.setText (address);
addComponent (this, new JLabel ("Round No "), 0, 3, 1, 1,
GridBagConstraints.NONE,
GridBagConstraints.WEST);
this.round = new JTextField (15);
addComponent (this, this.round, 1, 3, 1, 1,
GridBagConstraints.NONE,
GridBagConstraints.CENTER);
if (title.equals ("Update"))
this.round.setText (round);
addComponent (this, new JLabel ("Phone Number "), 0, 4, 1, 1,
GridBagConstraints.NONE,
GridBagConstraints.WEST);
this.phone = new JTextField (15);
addComponent (this, this.phone, 1, 4, 1, 1,
GridBagConstraints.NONE,
GridBagConstraints.CENTER);
if (title.equals ("Update"))
this.phone.setText (phone);
addComponent (this, new JLabel (""), 0, 5, 1, 1,
GridBagConstraints.NONE,
GridBagConstraints.CENTER);
addComponent (this, new JLabel (""), 1, 5, 1, 1,
GridBagConstraints.NONE,
GridBagConstraints.CENTER);
JButton b;
// Add an Ok button to this container.
addComponent (this, b = new JButton ("Ok"), 0, 6, 1, 1,
GridBagConstraints.NONE,
GridBagConstraints.CENTER);
b.addActionListener (this);
// Add a Cancel button to this container.
addComponent (this, b = new JButton ("Cancel"), 1, 6, 1, 1,
GridBagConstraints.NONE,
GridBagConstraints.CENTER);
b.addActionListener (this);
// Set the size of the dialog window to 250 pixels
// horizontally by 200 pixels vertically.
setSize (250, 200);
// Do not allow users to resize the dialog window.
setResizable (false);
// Make sure that the dialog window is visible.
setVisible (true);
private void addComponent (Container con, Component com,
int gridx, int gridy,
int gridw, int gridh, int fill,
int anchor)
// Get the current layout manager. It is assumed to
// be a GridBagLayout object.
LayoutManager lm = con.getLayout ();
// Create a GridBagConstraints object to make it
// possible to customize component positioning.
GridBagConstraints gbc = new GridBagConstraints ();
// Assign the x and y grid positions.
gbc.gridx = gridx;
gbc.gridy = gridy;
// Assign the number of grid blocks horizontally and
// vertically that are occupied by the component.
gbc.gridwidth = gridw;
gbc.gridheight = gridh;
// Specify the component's resize policy (fill) and
// the direction in which the component is positioned
// when its size is smaller than available space (anchor).
gbc.fill = fill;
gbc.anchor = anchor;
// Set the new constraints that the grid bag layout
// manager will use.
((GridBagLayout) lm).setConstraints (com, gbc);
// Add the component to the container.
con.add (com);
// ===========================================================
// Class: MsgBox
// This class displays a message box to the user. The message
// is usually an error message. The user must press the Ok
// button to terminate the message box.
// ===========================================================
class MsgBox extends JDialog implements ActionListener
public void actionPerformed (ActionEvent e)
// Terminate the dialog box in response to the user
// pressing the Ok button.
dispose ();
public MsgBox (JFrame parent, String title, String msg)
// Initialize the superclass layer.
super (parent, title, true);
// Store the msg argument in a Label object and add
// this object to the center part of the dialog window.
JLabel l = new JLabel (msg);
add ("Center", l);
// Create a Button object and add it to the south part
// of the dialog window.
JButton b = new JButton ("Ok");
add ("South", b);
// Make the current object a listener to events that
// occur as a result of the user pressing the Ok
// button.
b.addActionListener (this);
// Make sure that the Ok button has the focus.
b.requestFocus ();
// Do not allow users to resize the dialog window.
setResizable (false);
// Allow the layout manager to choose an appropriate
// size for the dialog window.
pack ();
// Make sure that the dialog window is visible.
setVisible (true);
}

Re: The difference between update() and doFinal() in ClassCipher

Hi Guys,
I found this topic,
The difference between update() and doFinal() in ClassCipher
during a Google Search. I need your help, because I'm working on a project for an university exam.
It's about a Client FTP that sends and received files with the content crypted.
I'm using DES Encryption with "DES/CBC/PKCS5Padding".
I have this doubt: when it's correct to uso the doFinal method? At the last block of the file, or after it? (for encryption)
And during the decryption, how can I use the result of the doFinal operation?

Reposting with {code} tags
capagira87 wrote:
Ok these are the functions:
public void CodificaInvia (String cd, String filename, SecretKey Key) // it opens, codes and sends to the server the content of the file 512 bytes per time
int returncode=0;
Socket DataSock = null;
FileInputStream fis = null;
byte [] text = null;
try {
DataSock = new Socket (servAddress,22);
ObjectInputStream cin = new ObjectInputStream (DataSock.getInputStream());
ObjectOutputStream out = new ObjectOutputStream (DataSock.getOutputStream());
byte[] iv = new byte[] { (byte) 0x8E, 0x12, 0x39, (byte) 0x9C, 0x07, 0x72, 0x6F, 0x5A };
AlgorithmParameterSpec paramSpec = new IvParameterSpec(iv);
Cipher cipher = Cipher.getInstance("DES/CBC/PKCS5Padding");
cipher.init(Cipher.ENCRYPT_MODE, Key, paramSpec);
fis = new FileInputStream (cd+File.separator+filename);
int size = fis.available();
if ((size%8)==0)
text = new byte [size];
} else {
do {
size++;
} while ((size%8)!=0);
text = new byte [size];
fis.read(text,0,fis.available());
byte [] ciphertext = cipher.doFinal(text);
out.writeInt(ciphertext.length);
int numblock = ciphertext.length/512;
int resto = ciphertext.length%512;
out.writeInt(numblock);
out.writeInt(resto);
byte [] tempblock = new byte [512];
for (int conta=0; conta<numblock; conta++)
for (int i=0; i<512; i++)
tempblock=ciphertext[(conta*512)+i];
out.write(tempblock);
out.flush();
if (resto > 0) // this block works if the file size is not multiple of 512
java.util.Arrays.fill (tempblock, (byte) 0);
int h= numblock*512;
for (int i=0; i<resto; i++)
tempblock[i]=ciphertext[h+i];
out.write (tempblock);
out.flush();
System.out.println ("OK!");
} catch (Exception e)
e.printStackTrace();
public void RicezioneDecodifica (String filename, SecretKey Key) // in this function I receive the file blocks, I decrpyt them and I save the decrypted text into a file
Socket DataSock = null;
byte [] buffer=null; // it saves the received data
String Plaintext = new String (); // it saves the deciphered text
try {
ServerSocket ss2 = new ServerSocket (TRANSMISSION_PORT);
DataSock = ss2.accept();
ObjectOutputStream out = new ObjectOutputStream (DataSock.getOutputStream());
ObjectInputStream cin = new ObjectInputStream (DataSock.getInputStream());
byte[] iv = new byte[] { (byte) 0x8E, 0x12, 0x39, (byte) 0x9C, 0x07, 0x72, 0x6F, 0x5A };
AlgorithmParameterSpec paramSpec = new IvParameterSpec(iv);
Cipher dcipher = Cipher.getInstance("DES/CBC/PKCS5Padding");
dcipher.init(Cipher.DECRYPT_MODE, Key, paramSpec);
int size = cin.readInt();
int numblock = cin.readInt();
int resto = cin.readInt();
if ((size%8)!=0)
do{
size++;
} while ((size%8)!=0);
int ByteLetti=0; // counter of read bytes
buffer = new byte [size];
for (int conta=0; conta<numblock; conta++)
int a=cin.available();
byte [] tempblock = new byte [a];
cin.read(tempblock, 0, a);
for (int i=0; i<a; i++)
buffer[ByteLetti+i]=tempblock[i];
ByteLetti=ByteLetti+a;
byte[] texttmp=dcipher.update(tempblock);
String tmp = new String (texttmp, "UTF8");
Plaintext=Plaintext+tmp;
if (resto>0)
int a = cin.available();
byte [] tempblock;
if ((a%8)>0)
do {
a++;
} while ((a%8)!=0);
tempblock = new byte [a];
cin.read(tempblock, 0, cin.available());
byte[] texttmp = dcipher.doFinal(tempblock);
String tmp = new String (texttmp, "UTF8");
Plaintext = Plaintext+tmp;
ObjectOutputStream oos = new ObjectOutputStream (new FileOutputStream (filename));
oos.writeChars(Plaintext);
oos.flush();
oos.close();
} catch (Exception e)
e.printStackTrace();

Difference between Null and null?

What is the difference between null and NULL?
When is each used?
Thanks,

veryConfused wrote:
There is a null in java, but no NULL. null means no value. However, when assigning value, the following is different:Although the empty String has no special role. Null means, the referential type is not assigned (doesn't refer) to a specific object. The empty String is just another object though, so seeing it or pointing it out as something special when it actually isn't at all (no more special than new Integer(0) or new Object[0]) just adds to the confusion.

Difference between GUI_UPLOAD and WS_UPLOAD

Hi,
Please make me clear about the difference between GUI_UPLOAD and WS_UPLOAD. In which cases we need to use these modules...??
Thanks,
Satish

I would suggest to always use the GUI_UPLOAD. I say this because this is the function module which is used in the GUI_UPLOAD method of the class CL_GUI_FRONTEND_SERVICES.   Really, you should probably use the class/method instead of the function module.
data: filename type string.
filename = p_file.
call method cl_gui_frontend_services=>gui_upload
         exporting
              filename                = filename
              filetype                = 'ASC'
         changing
              data_tab                = iflatf
         exceptions
              file_open_error         = 1
              file_read_error         = 2
              no_batch                = 3
              gui_refuse_filetransfer = 4
              no_authority            = 6
              unknown_error           = 7
              bad_data_format         = 8
              unknown_dp_error        = 12
              access_denied           = 13
              others                  = 17.
Regards,
Rich Heilman

Difference between char and varchar, also the difference between varchar2

Hi,
Can anyone explain me the difference between char and varchar, and also the difference between varchar and varchar2...

Varchar2 is variable width character data type, so if you define column with width 20 and insert only one character to tis column only, one character will be stored in database. Char is not variable width so when you define column with width 20 and insert one character to this column it will be right padded with 19 spaces to desired length, so you will store 20 characters in the dattabase (follow the example 1). Varchar data type from Oracle 9i is automaticlly promoted to varchar2 (follow example 2)
Example 1:
SQL> create table tchar(text1 char(10), text2 varchar2(10))
2 /
Table created.
SQL> insert into tchar values('krystian','krystian')
2 /
1 row created.
SQL> select text1, length(text1), text2, length(text2)
2 from tchar
3 /
TEXT1 LENGTH(TEXT1) TEXT2 LENGTH(TEXT2)
krystian 10 krystian 8
Example 2:
create table tvarchar(text varchar(10))
SQL> select table_name,column_name,data_type
2 from user_tab_columns
3 where table_name = 'TVARCHAR'
4 /
TABLE_NAME COLUMN_NAME DATA_TYPE
TVARCHAR TEXT VARCHAR2
Best Regards
Krystian Zieja / mob

The difference between Lion and Mountain Lion

Can some one explain to me the difference between Lion and Mtn Lion? I'm currently 10.6.8 Is it beneficiall for me to upgrade?

Mountain Lion is an enhanced version of previous OS X and so that is Mavericks.
About upgrading it all depends on what your needs are and if your hardware supports it.
System requirements for OS X Lion
System requirements for OS X Mountain Lion
OS X Mavericks: System Requirements
Please check also applications compatibility. From Lion onward, you cannot run PPC application.

The difference between N80 and N80IE ?

What is the difference between M80 and N80ie?

02-Jan-2007
07:45 PM
korngear wrote:
The Nokia N80 Internet Edition is a new version of this handset with the same hardware as the normal N80. It is due for release in Q4 of 2006 and will be available in Patina Bronze or Pearl Black, and has the following additional software included.
Yahoo Go! for Mobile
Flickr
Some Amazon Branded Software
'Download!' App management
Internet Telephone - SIP VOIP Frontend
WLAN Wizard
Gizmo VOIP - Gizmo Project VOIP Frontend.
\\en.wikipedia.org//
@Korngear
Thanks.
Could N80 be upgraded to N80IE?

The difference between SFP+ and X2

Dear Expert,
I need to know what is the difference between SFP+ and X2! and can I use SFP+ card and module instead of X2?
Thanks,
Mohammad Saeed

Hi,
They are both used for 10Gig interfaces. The difference is the connector type.
SFP+ is LC and X2 is SC.
You can not put an SFP+ into an X2 slot or X2 optic into a SFP+.
HTH

Difference between ok_code and sy-ucomm

Hi,
Can any one tell me the difference between ok_code and sy-ucomm

Hi,
Actually OK_CODE and SY-Ucomm are the same. But experts suggest use of OK code for following reason:
In each PAI event that a user triggers by choosing either a pushbutton on the screen or an element in a GUI status, the corresponding function code is placed into the system field SYST-UCOMM or SY-UCOMM and placed in the OK_CODE field (as long as the function code is not empty). Empty function codes are placed in neither the SY-UCOMM field nor the OK_CODE field.
In your ABAP programs, you should work with the OK_CODE field instead of SY-UCOMM. There are two reasons for this: Firstly, the ABAP program has full control over fields declared within it, and secondly, you should never change the value of an ABAP system field. However, you should also always initialize the OK_CODE field in an ABAP program for the following reason:
In the same way that the OK_CODE field in the ABAP program and the system field SY-UCOMM receive the contents of the corresponding screen fields in the PAI event, their contents are also assigned to the OK_CODE screen field and system field SYST-UCOMM in the PBO event. Therefore, you must clear the OK_CODE field in the ABAP program to ensure that the function code of a screen is not already filled in the PBO event with an unwanted value. This is particularly important when the next PAI event can be triggered with an empty function code (for example, using ENTER). Empty function codes do not affect SY-UCOMM or the OK_CODE field, and consequently, the old field contents are transported.

What is difference between abstraction and encapsulation ?

Hi,
I am trying to figure out the difference between abstraction and encapsulation but confused.
Both are used for data hiding then what is the exact difference ?
Thanks.

Tushar-Patel wrote:
I am trying to figure out the difference between abstraction and encapsulation but confused.
Both are used for data hiding then what is the exact difference ?This is the picture I have:
When you encapsulate something you get an inside and an outside. The outside is the abstraction. It describes how the encapsulated entity behaves viewed from the outside. This is also called the type. Hidden inside is the implementation. It holds detail information about how the type's behaviour is accomplished.
It's a very simplified picture but I think it's quite accurate and it works for me.

What is difference between Iterator and Collection Wrapper?

Hi all,
I dont understand the actual difference between Iterator and Collection Wrapper. I observed both are used for the same purpose. Could any one please let me know when to use Collection Wrapper and when to use Iterator??
Thanks,
Chinnu.

L_Kiryl is right.
Collections support global iteration (through collection->get_next( )) and local iteration (through iterator->get_next( )).
Each collection has a focus object. Initially, the first object has the focus.
Any global iteration moves the focus, which is published by the event FOCUS_CHANGED of the collection.
If you want to iterate on the collection without moving the focus (and without triggering timeconsuming follow-up processes) you can use local iteration. To do so, request an iterator object from the collection and use this to iterate.
And one more advantage of using iterator: it takes care of deleted entities. If you use global iteration then when you reach deleted entity it will be an exception. But there is no exception with iterator in the same situation.

What is difference between modify and update i am using

hi
what is difference between mofify and update
my requiremen is to have three condition checkec while mofifying or updating from a internal table
the three fields are
cus no
status
date these all are primary key in the database table
so which sould i use modify or update
there might be entry already existing in database table or new entry to be created if already existin it should check on the primary keys and updatat if not it should add a record
pls suggest whihc to use and how to implement the check on teh threee primary key
like if modify ztable from table it_test
now where condition ? can be used or not with modify? and if yes how
if not should i use update will update create a new entry if no entry is there and please give syntex
regards
Arora

Hi Nishant Arora,
Modify: It works in performing two actions.
They are: Insert + Update.
For Example If a record that is exited in database, so you are modifying that record, it updates that particular record.
Similarly, If the is not existed in the database, you are modifying it, it inserts a new record.
Update: Update means just it updates the status, I mean it only updates the record. It doesn't inserts any new record if that particular record is not present in the database.
These are the cases you need to write these statements.
Syntaxes: :
Go through this links please.,
http://help.sap.com/saphelp_nw04/helpdata/en/e7/968aa8b2384dd9835f91e7f8470064/content.htm
http://help.sap.com/saphelp_nw70/helpdata/en/fc/eb35eb358411d1829f0000e829fbfe/content.htm
Reward points if useful
Cheers,
Swamy Kunche
Edited by: Swamy Kunche on Jun 11, 2008 2:41 PM

What is Difference between SXMB_MONI and SXMB_MONITOR?

what is Difference between SXMB_MONI and SXMB_MONITOR?
Can any explain to this question.please?

Hello,
Both are same.
SXMB_MONI is area menu which will contain all multiple transactions pertaining to monitoring.
SXMB_MONI contains some functions viz monitoring for Bridging, Archived Msgs, Job overview, persistence layer analysis.
SXI_monitor directly leads to the message monitoring for the IS, which is part of the SXMB_MONI.
SXI_MONITOR directly executes the monitoring report.
Thanks,
Satya

Can Oracle be forced to use the spatial index for sdo_filter in combination with an or clause? Difference between Enterprise and SE?

We’re seeing the following issue: sql - Can Oracle be forced to use the spatial index for sdo_filter in combination with an or clause? - Stack Overflow (posted by a colleague of mine) and are curious to know if this behaviour is due to a difference between standard and enterprise, or could we doing something else wrong in our DB config.?
We have also reproduced the issue on the following stacks:
Oracle SE One 11.2.0.3 (with Spatial enabled)
Redhat Linux 2.6.32-358.6.2.el6.x86_64 #1 SMP Thu May 16 20:59:36 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux
11.2.0.3.0 Standard Edition and 11.2.0.4.0 Standard Edition (both with Spatial enabled)
Microsoft Windows Server 2003R2 Standard x64 Edition
However, the SQL works fine if we try it on Oracle 11.2.0.3.0 *Enterprise* Edition.
Any help or advice would be much appreciated.
Kindest Regards,
Kevin

In my experience sdo_filter ALWAYS uses the spatial index, so that's not the problem. Since you did not provide the explain plans, we can't say for sure but I think yhu is right: Standard Edition can't use the bitmap operations, and thus it'll take longer to combine the results of the two queries (because the optimizer will surely split this OR up in two parts, then combine them).
BTW: when asking questions about queries here, it would be nice if you posted the queries here as well, so that we do not have to check another website in order to see what you are doing. Plus it will probably get you more answers, because not everyone can be bothered to click on that link. It would also have been nice if you had posted your own answer on the other post here as well, because my recommendation would have been to use union all - but since you already found that out for yourself my recommendation would have been a little late.

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