File read and write : Input Output Stream « File Input Output « Java

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Java » File Input Output » Input Output StreamScreenshots 
File read and write
File read and write

/*
Software Architecture Design Patterns in Java
by Partha Kuchana 

Auerbach Publications

*/


import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Vector;

public class FileUtil {

  DataOutputStream dos;

  /*
   * Utility method to write a given text to a file
   */
  public boolean writeToFile(String fileName, String dataLine,
      boolean isAppendMode, boolean isNewLine) {
    if (isNewLine) {
      dataLine = "\n" + dataLine;
    }

    try {
      File outFile = new File(fileName);
      if (isAppendMode) {
        dos = new DataOutputStream(new FileOutputStream(fileName, true));
      else {
        dos = new DataOutputStream(new FileOutputStream(outFile));
      }

      dos.writeBytes(dataLine);
      dos.close();
    catch (FileNotFoundException ex) {
      return (false);
    catch (IOException ex) {
      return (false);
    }
    return (true);

  }

  /*
   * Reads data from a given file
   */
  public String readFromFile(String fileName) {
    String DataLine = "";
    try {
      File inFile = new File(fileName);
      BufferedReader br = new BufferedReader(new InputStreamReader(
          new FileInputStream(inFile)));

      DataLine = br.readLine();
      br.close();
    catch (FileNotFoundException ex) {
      return (null);
    catch (IOException ex) {
      return (null);
    }
    return (DataLine);

  }

  public boolean isFileExists(String fileName) {
    File file = new File(fileName);
    return file.exists();
  }

  public boolean deleteFile(String fileName) {
    File file = new File(fileName);
    return file.delete();
  }

  /*
   * Reads data from a given file into a Vector
   */

  public Vector fileToVector(String fileName) {
    Vector v = new Vector();
    String inputLine;
    try {
      File inFile = new File(fileName);
      BufferedReader br = new BufferedReader(new InputStreamReader(
          new FileInputStream(inFile)));

      while ((inputLine = br.readLine()) != null) {
        v.addElement(inputLine.trim());
      }
      br.close();
    // Try
    catch (FileNotFoundException ex) {
      //
    catch (IOException ex) {
      //
    }
    return (v);
  }

  /*
   * Writes data from an input vector to a given file
   */

  public void vectorToFile(Vector v, String fileName) {
    for (int i = 0; i < v.size(); i++) {
      writeToFile(fileName, (Stringv.elementAt(i), true, true);
    }
  }

  /*
   * Copies unique rows from a source file to a destination file
   */

  public void copyUniqueElements(String sourceFile, String resultFile) {
    Vector v = fileToVector(sourceFile);
    v = MiscUtil.removeDuplicates(v);
    vectorToFile(v, resultFile);
  }

// end FileUtil

class MiscUtil {

  public static boolean hasDuplicates(Vector v) {
    int i = 0;
    int j = 0;
    boolean duplicates = false;

    for (i = 0; i < v.size() 1; i++) {
      for (j = (i + 1); j < v.size(); j++) {
        if (v.elementAt(i).toString().equalsIgnoreCase(
            v.elementAt(j).toString())) {
          duplicates = true;
        }

      }

    }

    return duplicates;
  }

  public static Vector removeDuplicates(Vector s) {
    int i = 0;
    int j = 0;
    boolean duplicates = false;

    Vector v = new Vector();

    for (i = 0; i < s.size(); i++) {
      duplicates = false;
      for (j = (i + 1); j < s.size(); j++) {
        if (s.elementAt(i).toString().equalsIgnoreCase(
            s.elementAt(j).toString())) {
          duplicates = true;
        }

      }
      if (duplicates == false) {
        v.addElement(s.elementAt(i).toString().trim());
      }

    }

    return v;
  }

  public static Vector removeDuplicateDomains(Vector s) {
    int i = 0;
    int j = 0;
    boolean duplicates = false;
    String str1 = "";
    String str2 = "";

    Vector v = new Vector();

    for (i = 0; i < s.size(); i++) {
      duplicates = false;
      for (j = (i + 1); j < s.size(); j++) {
        str1 = "";
        str2 = "";
        str1 = s.elementAt(i).toString().trim();
        str2 = s.elementAt(j).toString().trim();
        if (str1.indexOf('@'> -1) {
          str1 = str1.substring(str1.indexOf('@'));
        }
        if (str2.indexOf('@'> -1) {
          str2 = str2.substring(str2.indexOf('@'));
        }

        if (str1.equalsIgnoreCase(str2)) {
          duplicates = true;
        }

      }
      if (duplicates == false) {
        v.addElement(s.elementAt(i).toString().trim());
      }

    }

    return v;
  }

  public static boolean areVectorsEqual(Vector a, Vector b) {
    if (a.size() != b.size()) {
      return false;
    }

    int i = 0;
    int vectorSize = a.size();
    boolean identical = true;

    for (i = 0; i < vectorSize; i++) {
      if (!(a.elementAt(i).toString().equalsIgnoreCase(b.elementAt(i)
          .toString()))) {
        identical = false;
      }
    }

    return identical;
  }

  public static Vector removeDuplicates(Vector a, Vector b) {

    int i = 0;
    int j = 0;
    boolean present = true;
    Vector v = new Vector();

    for (i = 0; i < a.size(); i++) {
      present = false;
      for (j = 0; j < b.size(); j++) {
        if (a.elementAt(i).toString().equalsIgnoreCase(
            b.elementAt(j).toString())) {
          present = true;
        }
      }
      if (!(present)) {
        v.addElement(a.elementAt(i));
      }
    }

    return v;
  }

}// end of class



           
       
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4.Input and output of arrays and objects with binary filesInput and output of arrays and objects with binary files
5.Input and output of primitive values with random access binary filesInput and output of primitive values with random access binary files
6.Input and output using strings and string buffersInput and output using strings and string buffers
7.Timing Unbuffered Reads
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9.Comparing Buffered and Unbuffered Writing Performance
10.Read a file and print, using LineReader and System.out
11.Demonstrate ProgressMeterInputStream
12.Converting text to and from ByteBuffersConverting text to and from ByteBuffers
13.Demonstrates standard I/O redirection
14.Creating a very large file using mappingCreating a very large file using mapping
15.Demonstrates the use of the File class to create directories and manipulate files
16.Mapping an entire file into memory for reading
17.Mapped IOMapped IO
18.What happens when the entire file isn't in your mapping region
19.Object serializationObject serialization
20.Locking portions of a mapped fileLocking portions of a mapped file
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