Files And Streams

a. Using the Files Classb. Random Access Filesc. Streamd. Byte and character Streame. Buffered Reader

Files and Stream

Use the File class for typical operations such as copying, moving, renaming, creating, opening, deleting, and appending to files. You can also use the File class to get and set file attributes or Date Time  information related to the creation, access, and writing of a file.

Using The FILE Class

random access files as their name implies, once they are opened, they can be read from or written to in a random manner just by using a record number or you can add to the end since you will know how many records are in the file.

Random Access Files

Stream is the abstract base class of all streams. A stream is an abstraction of a sequence of bytes, such as a file, an input/output device, an inter-process communication pipe, or a TCP/IP socket. The Stream class and its derived classes provide a generic view of these different types of input and output, isolating the programmer from the specific details of the operating system and the underlying devices.

STREAMS

three fundamental operations

1.You can read from streams. Reading is the transfer of data from a stream into a data structure, such as an array of bytes.

2.You can write to streams. Writing is the transfer of data from a data structure into a stream.

3.Streams can support seeking. Seeking is the querying and modifying of the current position within a stream. Seek

Character streams are intended exclusively for character data. Byte streams are intended for general purpose input and output. Of course, fundamentally all data consist of patterns of bits grouped into 8-bit bytes. So, logically all streams could be called "byte streams". However streams that are intended for bytes that represent characters are called "character streams" and all others are called "byte streams".

Byte and Character Streams

Buffered Stream can be composed around certain types of streams. It provides implementations for reading and writing bytes to an underlying data source or repository. Use Binary Reader and Binary Writer  for reading and writing other data types. 

Buffered Streams

catch(FileNotFoundException ex){

System.out.println(ex.getMessage() + " in the specified directory.");

System.exit(0); } catch(IOException e){

System.out.println(e.getMessage());

} } public static void main(String[]

args){ copyfile("c:\\out.txt","d:\\

kulafu.edi");

} }

import java.io.*;

public class CopyFile{ private static void copyfile(String srFile,

String dtFile){ try{ File f1 = new File(srFile); File f2 = new File(dtFile); InputStream in = new FileInputStream(f1); //For Append the file. // OutputStream out = new

FileOutputStream(f2,true);

//For Overwrite the file. OutputStream out = new

FileOutputStream(f2);

byte[] buf = new byte[1024]; int len; while ((len = in.read(buf)) > 0){ out.write(buf, 0, len); } in.close(); out.close(); System.out.println("File copied."); }

import java.io.*;class FileWrite { public static void main(String args[]) { try{ // Create file FileWriter fstream = new FileWriter("out.txt"); BufferedWriter out = new BufferedWriter(fstream); out.write("pink"); //Close the output stream out.close(); }catch (Exception e){//Catch exception if any System.err.println("Error: " + e.getMessage()); } }}

import java.io.*;

public class ReadAccessFile{ public static void main(String[] args) throws IOException{ BufferedReader in = new BufferedReader(new InputStreamReader(System.in)); System.out.print("Enter File name : "); String str = in.readLine(); File file = new File(str); if(!file.exists()) { System.out.println("File does not exist."); System.exit(0); }

try { // Send data to the client. Console.Write("Sending data ... "); int bytesSent = serverSocket.Send( dataToSend, 0, dataToSend.Length, SocketFlags.None); Console.WriteLine("{0} bytes sent.\n", bytesSent.ToString());

// Set the timeout for receiving data to 2 seconds. serverSocket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReceiveTimeout, 2000);

// Receive data from the client. Console.Write("Receiving data ... "); try { do { bytesReceived = serverSocket.Receive(receivedData, 0, receivedData.Length, SocketFlags.None); totalReceived += bytesReceived; } while(bytesReceived != 0); } catch(SocketException e) { if(e.ErrorCode == WSAETIMEDOUT) { // Data was not received within the given time. // Assume that the transmission has ended. } else { Console.WriteLine("{0}: {1}\n", e.GetType().Name, e.Message); } } finally { Console.WriteLine("{0} bytes received.\n", totalReceived.ToString()); } } finally { serverSocket.Shutdown(SocketShutdown.Both); Console.WriteLine("Connection shut down."); serverSocket.Close(); } } }

public class Server { static void Main() { // This is a Windows Sockets 2 error code. const int WSAETIMEDOUT = 10060;

Socket serverSocket; int bytesReceived, totalReceived = 0; byte[] receivedData = new byte[2000000];

// Create random data to send to the client. byte[] dataToSend = new byte[2000000]; new Random().NextBytes(dataToSend);

IPAddress ipAddress = Dns.Resolve(Dns.GetHostName()).AddressList[0];

IPEndPoint ipEndpoint = new IPEndPoint(ipAddress, 1800);

// Create a socket and listen for incoming connections.

using(Socket listenSocket = new Socket( AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp)) { listenSocket.Bind(ipEndpoint); listenSocket.Listen(1);

// Accept a connection and create a socket to handle it.

serverSocket = listenSocket.Accept(); Console.WriteLine("Server is connected.\n"); }

import java.io.FileReader;import java.io.FileWriter;import java.io.IOException;

public class CopyCharacters { public static void main(String[] args) throws IOException {

FileReader inputStream = null; FileWriter outputStream = null;

try { inputStream = new FileReader("xanadu.txt"); outputStream = new FileWriter("characteroutput.txt");

int c; while ((c = inputStream.read()) != -1) { outputStream.write(c); } } finally { if (inputStream != null) { inputStream.close(); } if (outputStream != null) { outputStream.close(); } } }}