CS 535: Object-Oriented Programming & Design

1. References
2. File
   1. Creating Directories
   2. Creating Files
   3. Some File Data
   4. Machine Independence
   5. FixJavaDoc - An Example
3. StreamTokenizer
   1. Terms and Defaults
      1. EOL Example
      2. Default Comment Character
      3. Quote Character
   2. Some Real Parsing

Doc 18 Java IO: File, StreamTokenizer Slide # 1

Doc 18 Java IO: File, StreamTokenizer Slide # 2

absolute path name

path name relative to the current working directory

Doc 18 Java IO: File, StreamTokenizer Slide # 3

import java.io.File;
import java.io.IOException;

class CreatingDirectories
   {
   public static void main( String args[] ) throws IOException
      {
      // One directory
      File courseDirectory = new File( "cs535" );
      courseDirectory.mkdir();
      
      // Subdirectory
      File gradesDirectory = new File( "cs535/grades" );
      gradesDirectory.mkdir();
      
      // Multiple directories
      // test and this must exist before this will work
      File  oneAtATime  =  new File(  "test/this/out"  );
      boolean createResult = oneAtATime.mkdir();

      if ( createResult )
         System.out.println( "Created test/this/out");
      else
         System.out.println( "Failed to create test/this/out");

      // creates all four directories at once
      File  severalAtOnce  =  new File( "second/test/of/this"  );
      
      if ( !severalAtOnce.exists() )
         createResult = severalAtOnce.mkdirs();
      }
   }

Doc 18 Java IO: File, StreamTokenizer Slide # 4

import java.io.*;

class Test
   {
   public static void main( String args[] ) throws IOException
      {
      // Open/Create file for writing

      FileWriter writeableFile = new FileWriter( "RightHere" );
      
      // Open file for reading, IOException if does not exists

      FileReader info = new FileReader( "ReadMe");
      
      // Safer Way

      File readMe = new File( "ReadeMe" );
      FileReader moreInfo;
      if ( readMe.exists() )
         moreInfo = new FileReader( readMe );
      
      // Open/Create file for appending

      boolean append = true;
      FileWriter exam = new FileWriter( "exam", append );
      PrintWriter cout = new PrintWriter( 
            new BufferedWriter( exam ));
      
      cout.println( "Question One: Write a class to...");
      cout.close();
      }
   }
Doc 18 Java IO: File, StreamTokenizer Slide # 5

import java.io.*;
import java.util.*
class FileInfo
   {
   public static void main( String args[] ) throws IOException
      {
      File exam = new File( "Exam" );

      System.out.println( "Absolute Path: " + 
                              exam.getAbsolutePath()  );

      System.out.println( "Path: " + exam.getPath()  );

      System.out.println( "Name: " + exam.getName()  );

      System.out.println( "Parent: " + exam.getParent()  );

      System.out.println( "Can read: " + exam.canRead()  );

      System.out.println( "Can write: " + exam.canWrite()  );

      System.out.println( "Length: " + exam.length()  );

      System.out.println( "Modified?: " + exam.lastModified()  );
      System.out.println( "Modified!: " + 
                              new Date(exam.lastModified())  );
      }
   }

Doc 18 Java IO: File, StreamTokenizer Slide # 6

import java.io.*;
class  MachineIndependentFileNames
   {
   public  static  void  main( String  args[]  )
      {
      String  macFile  =  ":home:ma:whitney:cs596:grades";

      String currentPlatformFile
           =  gradeFile.replace( ':', File.separatorChar );

      }
   }
Doc 18 Java IO: File, StreamTokenizer Slide # 7

Doc 18 Java IO: File, StreamTokenizer Slide # 8

import java.io.*;

class ListAll
   {
   public static void main( String args[] ) throws IOException
      {
      File currentDirectory = new File( "." );
      String[] listing = currentDirectory.list();
      
      for ( int k = 0; k < listing.length; k++ )
         System.out.println( listing[k] );
      }
   }

Doc 18 Java IO: File, StreamTokenizer Slide # 9

import java.io.*;

class TheNoReuseWay
   {
   public static void main( String args[] ) throws IOException
      {
      File currentDirectory = new File( "." );
      String[] listing = currentDirectory.list();
      
      for ( int k = 0; k < listing.length; k++ )
         if ( listing[k].endsWith( ".html" ))
            System.out.println( listing[k] );
      }
   }

Doc 18 Java IO: File, StreamTokenizer Slide # 10

import java.io.*;

class Test
   {
   public static void main( String args[] ) throws IOException
      {
      File currentDirectory = new File( "." );
      String[] listing = currentDirectory.list( 
            new FileExtensionFilter("html"));
      
      for ( int k = 0; k < listing.length; k++ )
         System.out.println( listing[k] );
      }
   }

public class FileExtensionFilter implements FilenameFilter
   {
   String fileExtension;
   
   public FileExtensionFilter( String extension )
      {
      if ( extension.startsWith( "." ))
         fileExtension = extension;
      else
         fileExtension = "." + extension;
      }

    public  boolean accept(File dir, String name)
      {
      if ( name.endsWith( fileExtension ) )
         return true;
      else
         return false;
      }
   }

Doc 18 Java IO: File, StreamTokenizer Slide # 11

   static final String imageURL = 
      "src=\"http://www.eli.sdsu.edu/doc/images";
   static final String imageReference = "src=\"images";
   static Random randomNumber = new Random();
   
   public static void correctImageReference( String fileName) 
         throws Exception
      {
      File originalFile = new File( fileName );
      File scratchFile =  scratchFile();
      PrintWriter cout = null;
      StringReplaceReader fixed = null;
         
      BufferedReader bufferedFile = 
         new BufferedReader( new FileReader( originalFile ) );
      
      fixed = new StringReplaceReader( 
               bufferedFile, imageReference, imageURL);
         
      cout = new PrintWriter
         ( new BufferedWriter( new FileWriter( scratchFile )));
      
      cout.print( fixed.contents() );
         
      cout.close();
      fixed.close();
         
      originalFile.delete();
      scratchFile.renameTo( originalFile);
      }
Doc 18 Java IO: File, StreamTokenizer Slide # 12

   /**
    * Return a file which has a name
    * that does not exist in the current directory
    */
   public static File scratchFile()
      {

      String newFileName;
      File newFile;
      do
         {
         newFileName = "" + randomNumber.nextInt();
         newFile = new File( newFileName);
         }
      while ( newFile.exists() );

      return newFile;
      }
Doc 18 Java IO: File, StreamTokenizer Slide # 13

/**
 * This class fixes a problem with javadoc. Javadoc assumes that
 * all images are in a subdirectory of your current directory.
 * This class reads all files in the current directory that 
 * end in ".html". All references to standard java documentation
 * images in these files are modified to get the images over 
 * the network from www.eli.sdsu.edu.
 *
 * @author Peter Proud-Madruga, Roger Whitney
 * @version 0.8 20 October 1997
 */
class FixJavaDoc
   {
   static final String imageURL = "src=\"http://www.eli.sdsu.edu/doc/images";
   static final String imageReference = "src=\"images";
   static Random randomNumber = new Random();
   
   public static void main( String args[] ) throws Exception
      {
      File currentDirectory = new File( "." );
      String[] listing = currentDirectory.list( new FileExtensionFilter("html"));
      
      for ( int k = 0; k < listing.length; k++ )
         {
         System.out.println( "Processing file: " + listing[k]);
         correctImageReference( listing[k] );
         }
      }
   /**
    * Replaces all occurances of the string imageReference with 
    * the string imageURL in the file "fileName"
    */
   public static void correctImageReference( String fileName)
      {
      File originalFile = new File( fileName );
      File scratchFile =  scratchFile();
      PrintWriter cout = null;
      StringReplaceReader fixed = null;
      try
         {
         BufferedReader bufferedFile = 
            new BufferedReader( new FileReader( originalFile ) );
         
         //   StringReplaceReader will replace all occurrances
         // of imageReference with imageURL
         fixed = new StringReplaceReader( 
                  bufferedFile, imageReference, imageURL);
         
         cout = new PrintWriter
            ( new BufferedWriter( new FileWriter( scratchFile )));
         
         // fixed.contents returns file contents after making the 
         // changes
         cout.print( fixed.contents() );
         
         // can't delete or rename file that has an open stream 
         cout.close();
         fixed.close();
         
         originalFile.delete();
         scratchFile.renameTo( originalFile);
         }
         
      // only files that exist are opened for reading
      catch (FileNotFoundException shouldNotHappen)
         {
         System.err.println( "FileNotFoundException on existing file");
         shouldNotHappen.printStackTrace();
         }
         
      catch (IOException ioError )
         {
         System.err.println( "IO error while processing file: " + 
               fileName);
         ioError.printStackTrace();
         
         cout.close();
         scratchFile.delete();
         }
      }
   
   /**
    * Return a file which has a name
    * that does not exist in the current directory
    */
   public static File scratchFile()
      {
      String newFileName;
      File newFile;
      do
         {
         newFileName = "" + randomNumber.nextInt();
         newFile = new File( newFileName);
         }
      while ( newFile.exists() );
      return newFile;
      }
   }
Doc 18 Java IO: File, StreamTokenizer Slide # 14

More complex than the StringTokenizer

Designed to parse "Java-style" input

Parses numbers

Parses Java-style comments

Doc 18 Java IO: File, StreamTokenizer Slide # 15

sval for string (or word )

nval for number (declared a double not Double)

A string (word) was scanned

The string field sval contains the word scanned

A number was scanned

Only decimal floating-point numbers (with or without a decimal point) are recognized

End-of-line scanned

End-of-file scanned

Doc 18 Java IO: File, StreamTokenizer Slide # 16

import java.io.*;

class  Tokenizer  
   {
   public static void main( String args[] ) throws Exception 
      {
      String sample = "this 123 is an 3.14 \n simple test";
      InputStream in;
      in = new StringBufferInputStream( sample );
      StreamTokenizer parser = new StreamTokenizer( in );
      
      while ( parser.nextToken() != StreamTokenizer.TT_EOF )
         {
         if ( parser.ttype == StreamTokenizer.TT_WORD)
            System.out.println( "A word: " + parser.sval );
         else if  ( parser.ttype == StreamTokenizer.TT_NUMBER )
            System.out.println( "A number: " + parser.nval );
         else if  ( parser.ttype == StreamTokenizer.TT_EOL )
            System.out.println( "EOL" );
         else
            System.out.println( "Other: " + (char) parser.ttype );
         }   
      }
   }

Doc 18 Java IO: File, StreamTokenizer Slide # 17

Characters that are treated special

White space

Characters that make up numbers

Characters that make up words (tokens)

All nonspecial characters

a - z

A - Z

ascii values 130 through 255

ascii values 0 through 32

includes space, tab, line feed, carriage return, escape

Doc 18 Java IO: File, StreamTokenizer Slide # 18

  public void resetSyntax()

       Resets the syntax table so that all characters are special. 

  public void resetSyntax()

       Resets the syntax table so that all characters are special. 

  public void resetSyntax()

       Resets the syntax table so that all characters are ordinary. 

Doc 18 Java IO: File, StreamTokenizer Slide # 19

import java.io.*;

class  Tokenizer  
   {
   public static void main( String args[] ) throws Exception 
      { 
      String sample = "this 123 is an 3.14 \n simple test";
      InputStream in =  new StringBufferInputStream( sample );
      StreamTokenizer parser = new StreamTokenizer( in );
      parser.eolIsSignificant( true ); 
      
      while ( parser.nextToken() != StreamTokenizer.TT_EOF )
         {
         if ( parser.ttype == StreamTokenizer.TT_WORD)
            System.out.println( "A word: " + parser.sval );
         else if  ( parser.ttype == StreamTokenizer.TT_NUMBER )
            System.out.println( "A number: " + parser.nval );
         else if  ( parser.ttype == StreamTokenizer.TT_EOL )
            System.out.println( "EOL" );
         else
            System.out.println( "Other: " + (char) parser.ttype );
         }   
      }
   }

Doc 18 Java IO: File, StreamTokenizer Slide # 20

import java.io.*;

class  Tokenizer  
   {
   public static void main( String args[] ) throws Exception 
      { 
      String sample = "this 123 /is an 3.14 \n simple test";

      InputStream in = new StringBufferInputStream( sample );
      StreamTokenizer parser = new StreamTokenizer( in );
      
      while ( parser.nextToken() != StreamTokenizer.TT_EOF )
         {
         if ( parser.ttype == StreamTokenizer.TT_WORD)
            System.out.println( "A word: " + parser.sval );
         else if  ( parser.ttype == StreamTokenizer.TT_NUMBER )
            System.out.println( "A number: " + parser.nval );
         else if  ( parser.ttype == StreamTokenizer.TT_EOL )
            System.out.println( "EOL" );
         else
            System.out.println( "Other: " + (char) parser.ttype );
         }   
      }
   }

Doc 18 Java IO: File, StreamTokenizer Slide # 21

import java.io.*;
class  Tokenizer  
   {
   public static void main( String args[] ) throws Exception 
      { 
      String sample = "this #123 /is an 3.14# \n simple test";

      InputStream in = new StringBufferInputStream( sample );
      StreamTokenizer parser = new StreamTokenizer( in );

      parser.quoteChar( '#' );

      while ( parser.nextToken() != StreamTokenizer.TT_EOF )
         {
         if ( parser.ttype == StreamTokenizer.TT_WORD)
            System.out.println( "A word: " + parser.sval );
         else if  ( parser.ttype == StreamTokenizer.TT_NUMBER )
            System.out.println( "A number: " + parser.nval );
         else if  ( parser.ttype == StreamTokenizer.TT_EOL )
            System.out.println( "EOL" );
         else
            System.out.println( "Other: " + (char) parser.ttype +
                           "sval: " + parser.sval );
         }   
      }
   }

Doc 18 Java IO: File, StreamTokenizer Slide # 22

import java.io.*;
class  Tokenizer  
   {
   public static void main( String args[] ) throws Exception 
      { 
      String sample = "this #123 /is an 3.14 \n simple # test";

      InputStream in = new StringBufferInputStream( sample );
      StreamTokenizer parser = new StreamTokenizer( in );

      parser.quoteChar( '#' );

      while ( parser.nextToken() != StreamTokenizer.TT_EOF )
         {
         if ( parser.ttype == StreamTokenizer.TT_WORD)
            System.out.println( "A word: " + parser.sval );
         else if  ( parser.ttype == StreamTokenizer.TT_NUMBER )
            System.out.println( "A number: " + parser.nval );
         else if  ( parser.ttype == StreamTokenizer.TT_EOL )
            System.out.println( "EOL" );
         else
            System.out.println( "Other: " + (char) parser.ttype +
                           "sval: " + parser.sval );
         }   
      }
   }

Doc 18 Java IO: File, StreamTokenizer Slide # 23

import java.io.*;
class  Tokenizer  {
   public static void main( String args[] ) throws Exception { 

      String sample = "this #123 /is an 3.14 \n simple # test";

      InputStream in = new StringBufferInputStream( sample );
      StreamTokenizer parser = new StreamTokenizer( in );

      parser.wordChars( 0, 255 );
      parser.ordinaryChar( 's' );

      while ( parser.nextToken() != StreamTokenizer.TT_EOF )
         {
         if ( parser.ttype == StreamTokenizer.TT_WORD)
            System.out.println( "A word: " + parser.sval );
         else if  ( parser.ttype == StreamTokenizer.TT_NUMBER )
            System.out.println( "A number: " + parser.nval );
         else if  ( parser.ttype == StreamTokenizer.TT_EOL )
            System.out.println( "EOL" );
         else
            System.out.println( "Other: " + (char) parser.ttype +
                           "sval: " + parser.sval );
         }   
      }
   }

A word: thi
Other: ssval: null
A word: #123 /i
Other: ssval: null
A word: an 3.14 
 
Other: ssval: null
A word: imple # te
Other: ssval: null
A word: t
Doc 18 Java IO: File, StreamTokenizer Slide # 24

class  Tokenizer  
   {
   public static void main( String args[] ) throws Exception 
      { 

      String sample = "name=value; sam = \n A";

      InputStream in = new StringBufferInputStream( sample );
      StreamTokenizer parser = new StreamTokenizer( in );

      parser.wordChars( 0, 255 );
      parser.whitespaceChars( 0, 32 );
      parser.ordinaryChar( ';' );
      parser.ordinaryChar( '=' );

      while ( parser.nextToken() != StreamTokenizer.TT_EOF )
         {
         if ( parser.ttype == StreamTokenizer.TT_WORD)

         // same as previous examples
         }   
      }
   }

Doc 18 Java IO: File, StreamTokenizer Slide # 25

class  Tokenizer  
   {
   public static void main( String args[] ) throws Exception 
      { 
      String sample = "name with space=value # a commment\n; "
                     + " 'sam =cat' = \n A";

      InputStream in = new StringBufferInputStream( sample );
      StreamTokenizer parser = new StreamTokenizer( in );

      parser.wordChars( 0, 255 );
      parser.whitespaceChars( 9, 13 ); //tab, line feed, return
      parser.ordinaryChar( ';' );
      parser.ordinaryChar( '=' );
      parser.commentChar( '#' );
      parser.quoteChar( '\'' );

      while ( parser.nextToken() != StreamTokenizer.TT_EOF )
         {
         // Same as other examples
         }   
      }
   }

Doc 18 Java IO: File, StreamTokenizer Slide # 26

   public static void main( String args[] ) throws Exception 
      { 
      String sample = "name;with;space=value # a commment\n; "
                     + "sam & cat = \n A";
      InputStream in = new StringBufferInputStream( sample );
      StreamTokenizer parser = new StreamTokenizer( in );

      parser.wordChars( 0, 255 );
      parser.whitespaceChars( 9, 13 ); //tab, line feed, return
      parser.ordinaryChar( '=' );
      parser.commentChar( '#' );

      while ( parser.nextToken() != StreamTokenizer.TT_EOF )
         {
         if ( parser.ttype == StreamTokenizer.TT_WORD)
            System.out.println( "A word: " + parser.sval );
         else if  ( parser.ttype == '=' )
            {
            System.out.println( "=: ");
            parser.ordinaryChar( ';' );
            parser.wordChars( '=', '=' );
            }
         else if  ( parser.ttype == ';' )
            {
            System.out.println( ";: " );
            parser.ordinaryChar( '=' );
            parser.wordChars( ';', ';' );
            }
         else
            System.out.println( "Error: " + (char) parser.ttype +
                           "sval: " + parser.sval );
         }   
      }
Doc 18 Java IO: File, StreamTokenizer Slide # 27

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