Java/File Input Output/Data Input Output

Controlling serialization by adding your own writeObject() and readObject() methods

// : c12:SerialCtl.java
// Controlling serialization by adding your own
// writeObject() and readObject() methods.
// From "Thinking in Java, 3rd ed." (c) Bruce Eckel 2002
// www.BruceEckel.ru. See copyright notice in CopyRight.txt.
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
public class SerialCtl implements Serializable {
  private String a;
  private transient String b;
  public SerialCtl(String aa, String bb) {
    a = "Not Transient: " + aa;
    b = "Transient: " + bb;
  }
  public String toString() {
    return a + "\n" + b;
  }
  private void writeObject(ObjectOutputStream stream) throws IOException {
    stream.defaultWriteObject();
    stream.writeObject(b);
  }
  private void readObject(ObjectInputStream stream) throws IOException,
      ClassNotFoundException {
    stream.defaultReadObject();
    b = (String) stream.readObject();
  }
  public static void main(String[] args) throws IOException,
      ClassNotFoundException {
    SerialCtl sc = new SerialCtl("Test1", "Test2");
    System.out.println("Before:\n" + sc);
    ByteArrayOutputStream buf = new ByteArrayOutputStream();
    ObjectOutputStream o = new ObjectOutputStream(buf);
    o.writeObject(sc);
    // Now get it back:
    ObjectInputStream in = new ObjectInputStream(new ByteArrayInputStream(
        buf.toByteArray()));
    SerialCtl sc2 = (SerialCtl) in.readObject();
    System.out.println("After:\n" + sc2);
  }
} ///:~

Data IO Demo

/* From http://java.sun.ru/docs/books/tutorial/index.html */
/*
 * Copyright (c) 2006 Sun Microsystems, Inc. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * -Redistribution of source code must retain the above copyright notice, this
 *  list of conditions and the following disclaimer.
 *
 * -Redistribution in binary form must reproduce the above copyright notice,
 *  this list of conditions and the following disclaimer in the documentation
 *  and/or other materials provided with the distribution.
 *
 * Neither the name of Sun Microsystems, Inc. or the names of contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 *
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
 * ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
 * OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MIDROSYSTEMS, INC. ("SUN")
 * AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
 * AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
 * DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST
 * REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL,
 * INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY
 * OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
 * EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
 *
 * You acknowledge that this software is not designed, licensed or intended
 * for use in the design, construction, operation or maintenance of any
 * nuclear facility.
 */
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.EOFException;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
public class DataIODemo {
  public static void main(String[] args) throws IOException {
    // write the data out
    DataOutputStream out = new DataOutputStream(new FileOutputStream(
        "invoice1.txt"));
    double[] prices = { 19.99, 9.99, 15.99, 3.99, 4.99 };
    int[] units = { 12, 8, 13, 29, 50 };
    String[] descs = { "Java T-shirt", "Java Mug", "Duke Juggling Dolls",
        "Java Pin", "Java Key Chain" };
    for (int i = 0; i < prices.length; i++) {
      out.writeDouble(prices[i]);
      out.writeChar("\t");
      out.writeInt(units[i]);
      out.writeChar("\t");
      out.writeChars(descs[i]);
      out.writeChar("\n");
    }
    out.close();
    // read it in again
    DataInputStream in = new DataInputStream(new FileInputStream(
        "invoice1.txt"));
    double price;
    int unit;
    StringBuffer desc;
    double total = 0.0;
    try {
      while (true) {
        price = in.readDouble();
        in.readChar(); // throws out the tab
        unit = in.readInt();
        in.readChar(); // throws out the tab
        char chr;
        desc = new StringBuffer(20);
        char lineSep = System.getProperty("line.separator").charAt(0);
        while ((chr = in.readChar()) != lineSep)
          desc.append(chr);
        System.out.println("You"ve ordered " + unit + " units of "
            + desc + " at $" + price);
        total = total + unit * price;
      }
    } catch (EOFException e) {
    }
    System.out.println("For a TOTAL of: $" + total);
    in.close();
  }
}

Data IO Test

/* From http://java.sun.ru/docs/books/tutorial/index.html */
/*
 * Copyright (c) 2006 Sun Microsystems, Inc. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * -Redistribution of source code must retain the above copyright notice, this
 *  list of conditions and the following disclaimer.
 *
 * -Redistribution in binary form must reproduce the above copyright notice,
 *  this list of conditions and the following disclaimer in the documentation
 *  and/or other materials provided with the distribution.
 *
 * Neither the name of Sun Microsystems, Inc. or the names of contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 *
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
 * ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
 * OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MIDROSYSTEMS, INC. ("SUN")
 * AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
 * AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
 * DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST
 * REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL,
 * INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY
 * OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
 * EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
 *
 * You acknowledge that this software is not designed, licensed or intended
 * for use in the design, construction, operation or maintenance of any
 * nuclear facility.
 */
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.EOFException;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
public class DataIOTest {
  public static void main(String[] args) throws IOException {
    // write the data out
    DataOutputStream out = new DataOutputStream(new FileOutputStream(
        "invoice1.txt"));
    double[] prices = { 19.99, 9.99, 15.99, 3.99, 4.99 };
    int[] units = { 12, 8, 13, 29, 50 };
    String[] descs = { "Java T-shirt", "Java Mug", "Duke Juggling Dolls",
        "Java Pin", "Java Key Chain" };
    for (int i = 0; i < prices.length; i++) {
      out.writeDouble(prices[i]);
      out.writeChar("\t");
      out.writeInt(units[i]);
      out.writeChar("\t");
      out.writeChars(descs[i]);
      out.writeChar("\n");
    }
    out.close();
    // read it in again
    DataInputStream in = new DataInputStream(new FileInputStream(
        "invoice1.txt"));
    double price;
    int unit;
    StringBuffer desc;
    double total = 0.0;
    try {
      while (true) {
        price = in.readDouble();
        in.readChar(); // throws out the tab
        unit = in.readInt();
        in.readChar(); // throws out the tab
        char chr;
        desc = new StringBuffer(20);
        char lineSep = System.getProperty("line.separator").charAt(0);
        while ((chr = in.readChar()) != lineSep)
          desc.append(chr);
        System.out.println("You"ve ordered " + unit + " units of "
            + desc + " at $" + price);
        total = total + unit * price;
      }
    } catch (EOFException e) {
    }
    System.out.println("For a TOTAL of: $" + total);
    in.close();
  }
}

Data IO Test 2

/* From http://java.sun.ru/docs/books/tutorial/index.html */
/*
 * Copyright (c) 2006 Sun Microsystems, Inc. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * -Redistribution of source code must retain the above copyright notice, this
 *  list of conditions and the following disclaimer.
 *
 * -Redistribution in binary form must reproduce the above copyright notice,
 *  this list of conditions and the following disclaimer in the documentation
 *  and/or other materials provided with the distribution.
 *
 * Neither the name of Sun Microsystems, Inc. or the names of contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 *
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
 * ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
 * OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MIDROSYSTEMS, INC. ("SUN")
 * AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
 * AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
 * DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST
 * REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL,
 * INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY
 * OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
 * EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
 *
 * You acknowledge that this software is not designed, licensed or intended
 * for use in the design, construction, operation or maintenance of any
 * nuclear facility.
 */
import java.io.EOFException;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
public class DataIOTest2 {
  public static void main(String[] args) throws IOException {
    // write the data out
    ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream(
        "invoice1.txt"));
    double[] prices = { 19.99, 9.99, 15.99, 3.99, 4.99 };
    int[] units = { 12, 8, 13, 29, 50 };
    String[] descs = { "Java T-shirt", "Java Mug", "Duke Juggling Dolls",
        "Java Pin", "Java Key Chain" };
    for (int i = 0; i < prices.length; i++) {
      out.writeDouble(prices[i]);
      out.writeChar("\t");
      out.writeInt(units[i]);
      out.writeChar("\t");
      out.writeChars(descs[i]);
      out.writeChar("\n");
    }
    out.close();
    // read it in again
    ObjectInputStream in = new ObjectInputStream(new FileInputStream(
        "invoice1.txt"));
    double price;
    int unit;
    String desc;
    double total = 0.0;
    try {
      while (true) {
        price = in.readDouble();
        in.readChar(); // throws out the tab
        unit = in.readInt();
        in.readChar(); // throws out the tab
        desc = in.readLine();
        System.out.println("You"ve ordered " + unit + " units of "
            + desc + " at $" + price);
        total = total + unit * price;
      }
    } catch (EOFException e) {
    }
    System.out.println("For a TOTAL of: $" + total);
    in.close();
  }
}

IO demo: DataOutputStream and DataInputStream

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.EOFException;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
public class DataIODemo1 {
  public static void main(String[] args) throws IOException {
    DataOutputStream out = new DataOutputStream(new FileOutputStream(
        "jexp.txt"));
    double[] prices = { 19.99, 9.99, 15.99, 3.99, 4.99 };
    int[] units = { 12, 8, 13, 29, 50 };
    String[] descs = { "Java", "Source ", "and",
        "Support."};
    for (int i = 0; i < prices.length; i++) {
      out.writeDouble(prices[i]);
      out.writeChar("\t");
      out.writeInt(units[i]);
      out.writeChar("\t");
      out.writeChars(descs[i]);
      out.writeChar("\n");
    }
    out.close();
    // read it in again
    DataInputStream in = new DataInputStream(new FileInputStream(
        "jexp.txt"));
    double price;
    int unit;
    String desc;
    double total = 0.0;
    try {
      while (true) {
        price = in.readDouble();
        in.readChar(); // throws out the tab
        unit = in.readInt();
        in.readChar(); // throws out the tab
        desc = in.readLine();
        System.out.println( unit );
        System.out.println( desc );
        System.out.println( desc );
        total = total + unit * price;
      }
    } catch (EOFException e) {
    }
    in.close();
  }
}

ProgressMonitorInputStream Demo

import java.awt.Color;
import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.InputStreamReader;
import javax.swing.JLabel;
import javax.swing.ProgressMonitorInputStream;
public class ProgressInputSample {
  public static final int NORMAL = 0;
  public static void main(String args[]) throws Exception {
    int returnValue = NORMAL;
    if (args.length != 1) {
      System.err.println("Usage:");
      System.err.println("java ProgressInput filename");
    } else {
      FileInputStream fis = new FileInputStream(args[0]);
      JLabel filenameLabel = new JLabel(args[0], JLabel.RIGHT);
      filenameLabel.setForeground(Color.black);
      Object message[] = { "Reading:", filenameLabel };
      ProgressMonitorInputStream pmis = new ProgressMonitorInputStream(null, message, fis);
      InputStreamReader isr = new InputStreamReader(pmis);
      BufferedReader br = new BufferedReader(isr);
      String line;
      while ((line = br.readLine()) != null) {
        System.out.println(line);
        Thread.sleep(500);
      }
      br.close();
    }
    // AWT Thread created - must exit
    System.exit(returnValue);
  }
}

Read Write Lock Test

/*
Software Architecture Design Patterns in Java
by Partha Kuchana 
Auerbach Publications
*/
public class ReadWriteLockTest {
  public static void main(String[] args) {
    Item item = new Item("CompScience-I");
    new MemberTransaction("Member1", item, "StatusCheck");
    new MemberTransaction("Member2", item, "StatusCheck");
    new MemberTransaction("Member3", item, "CheckOut");
    new MemberTransaction("Member4", item, "CheckOut");
    new MemberTransaction("Member5", item, "CheckOut");
    new MemberTransaction("Member6", item, "StatusCheck");
  }
}
class Item {
  private String name;
  private ReadWriteLock rwLock;
  private String status;
  public Item(String n) {
    name = n;
    rwLock = new ReadWriteLock();
    status = "N";
  }
  public void checkOut(String member) {
    rwLock.getWriteLock();
    status = "Y";
    System.out.println(member + " has been issued a write lock-ChkOut");
    rwLock.done();
  }
  public String getStatus(String member) {
    rwLock.getReadLock();
    System.out.println(member + " has been issued a read lock");
    rwLock.done();
    return status;
  }
  public void checkIn(String member) {
    rwLock.getWriteLock();
    status = "N";
    System.out.println(member + " has been issued a write lock-ChkIn");
    rwLock.done();
  }
}
class ReadWriteLock {
  private Object lockObj;
  private int totalReadLocksGiven;
  private boolean writeLockIssued;
  private int threadsWaitingForWriteLock;
  public ReadWriteLock() {
    lockObj = new Object();
    writeLockIssued = false;
  }
  /*
   * A read lock can be issued if there is no currently issued write lock and
   * there is no thread(s) currently waiting for the write lock
   */
  public void getReadLock() {
    synchronized (lockObj) {
      while ((writeLockIssued) || (threadsWaitingForWriteLock != 0)) {
        try {
          lockObj.wait();
        } catch (InterruptedException e) {
          //
        }
      }
      //System.out.println(" Read Lock Issued");
      totalReadLocksGiven++;
    }
  }
  /*
   * A write lock can be issued if there is no currently issued read or write
   * lock
   */
  public void getWriteLock() {
    synchronized (lockObj) {
      threadsWaitingForWriteLock++;
      while ((totalReadLocksGiven != 0) || (writeLockIssued)) {
        try {
          lockObj.wait();
        } catch (InterruptedException e) {
          //
        }
      }
      //System.out.println(" Write Lock Issued");
      threadsWaitingForWriteLock--;
      writeLockIssued = true;
    }
  }
  //used for releasing locks
  public void done() {
    synchronized (lockObj) {
      //check for errors
      if ((totalReadLocksGiven == 0) && (!writeLockIssued)) {
        System.out.println(" Error: Invalid call to release the lock");
        return;
      }
      if (writeLockIssued)
        writeLockIssued = false;
      else
        totalReadLocksGiven--;
      lockObj.notifyAll();
    }
  }
}
class MemberTransaction extends Thread {
  private String name;
  private Item item;
  private String operation;
  public MemberTransaction(String n, Item i, String p) {
    name = n;
    item = i;
    operation = p;
    start();
  }
  public void run() {
    //all members first read the status
    item.getStatus(name);
    if (operation.equals("CheckOut")) {
      System.out.println("\n" + name + " is ready to checkout the item.");
      item.checkOut(name);
      try {
        sleep(1);
      } catch (InterruptedException e) {
        //
      }
      item.checkIn(name);
    }
  }
}

ScanStreamTok - show scanning a file with StringTokenizer

/*
 * Copyright (c) Ian F. Darwin, http://www.darwinsys.ru/, 1996-2002.
 * All rights reserved. Software written by Ian F. Darwin and others.
 * $Id: LICENSE,v 1.8 2004/02/09 03:33:38 ian Exp $
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS""
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 * 
 * Java, the Duke mascot, and all variants of Sun"s Java "steaming coffee
 * cup" logo are trademarks of Sun Microsystems. Sun"s, and James Gosling"s,
 * pioneering role in inventing and promulgating (and standardizing) the Java 
 * language and environment is gratefully acknowledged.
 * 
 * The pioneering role of Dennis Ritchie and Bjarne Stroustrup, of AT&T, for
 * inventing predecessor languages C and C++ is also gratefully acknowledged.
 */

import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Reader;
import java.io.StreamTokenizer;
/**
 * ScanStreamTok - show scanning a file with StringTokenizer.
 *
 * @author  Ian Darwin, http://www.darwinsys.ru/
 * @version  $Id: ScanStreamTok.java,v 1.6 2004/02/17 00:17:54 ian Exp $
 */
public class ScanStreamTok {
  protected  StreamTokenizer tf;
  public static void main(String[] av) throws IOException {
    if (av.length == 0)
      new ScanStreamTok(
        new InputStreamReader(System.in)).process();
    else 
      for (int i=0; i<av.length; i++)
        new ScanStreamTok(av[i]).process();
  }
  /** Construct a file scanner by name */
  public ScanStreamTok(String fileName) throws IOException {
    tf = new StreamTokenizer(new FileReader(fileName));
  }
  /** Construct a file scanner by existing Reader */
  public ScanStreamTok(Reader rdr) throws IOException {
    tf = new StreamTokenizer(rdr);
  }
  protected void process() throws IOException {
    String s = null;
    int i;
    while ((i = tf.nextToken()) != StreamTokenizer.TT_EOF) {
      switch(i) {
      case StreamTokenizer.TT_EOF:
        System.out.println("End of file");
        break;
      case StreamTokenizer.TT_EOL:
        System.out.println("End of line");
        break;
      case StreamTokenizer.TT_NUMBER:
        System.out.println("Number " + tf.nval);
        break;
      case StreamTokenizer.TT_WORD:
        System.out.println("Word, length " + tf.sval.length() + "->" + tf.sval);
        break;
      default:
        System.out.println("What is it? i = " + i);
      }
    }
  }
}

Some simple file I-O primitives reimplemented in Java

/*
 * Copyright (c) Ian F. Darwin, http://www.darwinsys.ru/, 1996-2002.
 * All rights reserved. Software written by Ian F. Darwin and others.
 * $Id: LICENSE,v 1.8 2004/02/09 03:33:38 ian Exp $
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS""
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 * 
 * Java, the Duke mascot, and all variants of Sun"s Java "steaming coffee
 * cup" logo are trademarks of Sun Microsystems. Sun"s, and James Gosling"s,
 * pioneering role in inventing and promulgating (and standardizing) the Java 
 * language and environment is gratefully acknowledged.
 * 
 * The pioneering role of Dennis Ritchie and Bjarne Stroustrup, of AT&T, for
 * inventing predecessor languages C and C++ is also gratefully acknowledged.
 */
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.io.Reader;
import java.io.Writer;
/**
 * Some simple file I-O primitives reimplemented in Java. All methods are
 * static, since there is no state.
 * 
 * @version $Id: FileIO.java,v 1.18 2004/05/30 01:39:27 ian Exp $
 */
public class FileIO {
  /** Nobody should need to create an instance; all methods are static */
  private FileIO() {
    // Nothing to do
  }
  /** Copy a file from one filename to another */
  public static void copyFile(String inName, String outName)
      throws FileNotFoundException, IOException {
    BufferedInputStream is = new BufferedInputStream(new FileInputStream(
        inName));
    BufferedOutputStream os = new BufferedOutputStream(
        new FileOutputStream(outName));
    copyFile(is, os, true);
  }
  /** Copy a file from an opened InputStream to opened OutputStream */
  public static void copyFile(InputStream is, OutputStream os, boolean close)
      throws IOException {
    byte[] b = new byte[BLKSIZ]; // the byte read from the file
    int i;
    while ((i = is.read(b)) != -1) {
      os.write(b, 0, i);
    }
    is.close();
    if (close)
      os.close();
  }
  /** Copy a file from an opened Reader to opened Writer */
  public static void copyFile(Reader is, Writer os, boolean close)
      throws IOException {
    int b; // the byte read from the file
    BufferedReader bis = new BufferedReader(is);
    while ((b = is.read()) != -1) {
      os.write(b);
    }
    is.close();
    if (close)
      os.close();
  }
  /** Copy a file from a filename to a PrintWriter. */
  public static void copyFile(String inName, PrintWriter pw, boolean close)
      throws FileNotFoundException, IOException {
    BufferedReader ir = new BufferedReader(new FileReader(inName));
    copyFile(ir, pw, close);
  }
  /** Open a file and read the first line from it. */
  public static String readLine(String inName) throws FileNotFoundException,
      IOException {
    BufferedReader is = new BufferedReader(new FileReader(inName));
    String line = null;
    line = is.readLine();
    is.close();
    return line;
  }
  /** The size of blocking to use */
  protected static final int BLKSIZ = 16384;
  /**
   * Copy a data file from one filename to another, alternate method. As the
   * name suggests, use my own buffer instead of letting the BufferedReader
   * allocate and use the buffer.
   */
  public void copyFileBuffered(String inName, String outName)
      throws FileNotFoundException, IOException {
    InputStream is = new FileInputStream(inName);
    OutputStream os = new FileOutputStream(outName);
    int count = 0; // the byte count
    byte[] b = new byte[BLKSIZ]; // the bytes read from the file
    while ((count = is.read(b)) != -1) {
      os.write(b, 0, count);
    }
    is.close();
    os.close();
  }
  /** Read the entire content of a Reader into a String */
  public static String readerToString(Reader is) throws IOException {
    StringBuffer sb = new StringBuffer();
    char[] b = new char[BLKSIZ];
    int n;
    // Read a block. If it gets any chars, append them.
    while ((n = is.read(b)) > 0) {
      sb.append(b, 0, n);
    }
    // Only construct the String object once, here.
    return sb.toString();
  }
  /** Read the content of a Stream into a String */
  public static String inputStreamToString(InputStream is) throws IOException {
    return readerToString(new InputStreamReader(is));
  }
  /** Write a String as the entire content of a File */
  public static void stringToFile(String text, String fileName)
      throws IOException {
    BufferedWriter os = new BufferedWriter(new FileWriter(fileName));
    os.write(text);
    os.flush();
    os.close();
  }
  /** Open a BufferedReader from a named file. */
  public static BufferedReader openFile(String fileName) throws IOException {
    return new BufferedReader(new FileReader(fileName));
  }
}

The use of DataOutputStream and DataInputStream:

 
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
class DataIODemo {
  public static void main(String args[]) throws IOException {
    FileOutputStream fout = new FileOutputStream("Test.dat");
    DataOutputStream out = new DataOutputStream(fout);
    out.writeDouble(98.6);
    out.writeInt(1000);
    out.writeBoolean(true);
    out.close();
    FileInputStream fin = new FileInputStream("Test.dat");
    DataInputStream in = new DataInputStream(fin);
    double d = in.readDouble();
    int i = in.readInt();
    boolean b = in.readBoolean();
    System.out.println("Here are the values:  " + d + " " + i + " " + b);
    in.close();
  }
}

Typical I/O stream configurations

// : c12:IOStreamDemo.java
// Typical I/O stream configurations.
// {RunByHand}
// {Clean: IODemo.out,Data.txt,rtest.dat}
// From "Thinking in Java, 3rd ed." (c) Bruce Eckel 2002
// www.BruceEckel.ru. See copyright notice in CopyRight.txt.
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.ByteArrayInputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.EOFException;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.io.RandomAccessFile;
import java.io.StringReader;
public class IOStreamDemo {
  // Throw exceptions to console:
  public static void main(String[] args) throws IOException {
    // 1. Reading input by lines:
    BufferedReader in = new BufferedReader(new FileReader(
        "IOStreamDemo.java"));
    String s, s2 = new String();
    while ((s = in.readLine()) != null)
      s2 += s + "\n";
    in.close();
    // 1b. Reading standard input:
    BufferedReader stdin = new BufferedReader(new InputStreamReader(
        System.in));
    System.out.print("Enter a line:");
    System.out.println(stdin.readLine());
    // 2. Input from memory
    StringReader in2 = new StringReader(s2);
    int c;
    while ((c = in2.read()) != -1)
      System.out.print((char) c);
    // 3. Formatted memory input
    try {
      DataInputStream in3 = new DataInputStream(new ByteArrayInputStream(
          s2.getBytes()));
      while (true)
        System.out.print((char) in3.readByte());
    } catch (EOFException e) {
      System.err.println("End of stream");
    }
    // 4. File output
    try {
      BufferedReader in4 = new BufferedReader(new StringReader(s2));
      PrintWriter out1 = new PrintWriter(new BufferedWriter(
          new FileWriter("IODemo.out")));
      int lineCount = 1;
      while ((s = in4.readLine()) != null)
        out1.println(lineCount++ + ": " + s);
      out1.close();
    } catch (EOFException e) {
      System.err.println("End of stream");
    }
    // 5. Storing & recovering data
    try {
      DataOutputStream out2 = new DataOutputStream(
          new BufferedOutputStream(new FileOutputStream("Data.txt")));
      out2.writeDouble(3.14159);
      out2.writeUTF("That was pi");
      out2.writeDouble(1.41413);
      out2.writeUTF("Square root of 2");
      out2.close();
      DataInputStream in5 = new DataInputStream(new BufferedInputStream(
          new FileInputStream("Data.txt")));
      // Must use DataInputStream for data:
      System.out.println(in5.readDouble());
      // Only readUTF() will recover the
      // Java-UTF String properly:
      System.out.println(in5.readUTF());
      // Read the following double and String:
      System.out.println(in5.readDouble());
      System.out.println(in5.readUTF());
    } catch (EOFException e) {
      throw new RuntimeException(e);
    }
    // 6. Reading/writing random access files
    RandomAccessFile rf = new RandomAccessFile("rtest.dat", "rw");
    for (int i = 0; i < 10; i++)
      rf.writeDouble(i * 1.414);
    rf.close();
    rf = new RandomAccessFile("rtest.dat", "rw");
    rf.seek(5 * 8);
    rf.writeDouble(47.0001);
    rf.close();
    rf = new RandomAccessFile("rtest.dat", "r");
    for (int i = 0; i < 10; i++)
      System.out.println("Value " + i + ": " + rf.readDouble());
    rf.close();
  }
} ///:~

Using transferTo() between channels

// : c12:TransferTo.java
// Using transferTo() between channels
// {Args: TransferTo.java TransferTo.txt}
// {Clean: TransferTo.txt}
// From "Thinking in Java, 3rd ed." (c) Bruce Eckel 2002
// www.BruceEckel.ru. See copyright notice in CopyRight.txt.
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.nio.channels.FileChannel;
public class TransferTo {
  public static void main(String[] args) throws Exception {
    if (args.length != 2) {
      System.out.println("arguments: sourcefile destfile");
      System.exit(1);
    }
    FileChannel in = new FileInputStream(args[0]).getChannel(), out = new FileOutputStream(
        args[1]).getChannel();
    in.transferTo(0, in.size(), out);
    // Or:
    // out.transferFrom(in, 0, in.size());
  }
} ///:~

Write some data in binary

/*
 * Copyright (c) Ian F. Darwin, http://www.darwinsys.ru/, 1996-2002.
 * All rights reserved. Software written by Ian F. Darwin and others.
 * $Id: LICENSE,v 1.8 2004/02/09 03:33:38 ian Exp $
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS""
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 * 
 * Java, the Duke mascot, and all variants of Sun"s Java "steaming coffee
 * cup" logo are trademarks of Sun Microsystems. Sun"s, and James Gosling"s,
 * pioneering role in inventing and promulgating (and standardizing) the Java 
 * language and environment is gratefully acknowledged.
 * 
 * The pioneering role of Dennis Ritchie and Bjarne Stroustrup, of AT&T, for
 * inventing predecessor languages C and C++ is also gratefully acknowledged.
 */
import java.io.DataOutputStream;
import java.io.FileOutputStream;
import java.io.IOException;
/**
 * Write some data in binary.
 * 
 * @author Ian F. Darwin, http://www.darwinsys.ru/
 * @version $Id: WriteBinary.java,v 1.3 2004/02/08 23:57:29 ian Exp $
 */
public class WriteBinary {
  public static void main(String[] argv) throws IOException {
    int i = 42;
    double d = Math.PI;
    String FILENAME = "binary.dat";
    DataOutputStream os = new DataOutputStream(new FileOutputStream(
        FILENAME));
    os.writeInt(i);
    os.writeDouble(d);
    os.close();
    System.out.println("Wrote " + i + ", " + d + " to file " + FILENAME);
  }
}