Writing Your Own Java I/O Stream Classes

 
  import java.io.* ;

  
  public class   TeeOutputStream
         extends OutputStream
  {
      OutputStream tee = null, out = null;
  
  
     public TeeOutputStream(OutputStream chainedStream, 
                             OutputStream teeStream)
      {
           out = chainedStream;
  
           if (teeStream == null)
               tee = System.out;
           else
               tee = teeStream;
      }
      
  
  /**
  * Implementation for parent's abstract write method.  
  * This writes out the passed in character to the both,
  * the chained stream and "tee" stream.
  */
       
      public void write(int c) throws IOException
      {
           out.write(c);
  
           tee.write(c);
           tee.flush();
      }
  
  
      /**
       * Closes both, chained and tee, streams.
       */
      public void close() throws IOException
      {
           flush();
  
           out.close();
           tee.close();
      }
  
  
   /**
   * Flushes chained stream; the tee stream is flushed 
   * each time a character is written to it.
   */
      public void flush() throws IOException
      {
           out.flush();
      }
  
  
  
   /** Test driver */
   public static void main(
     String args[]) throws Exception
      {
          FileOutputStream fos =
                new FileOutputStream("test.out");
          TeeOutputStream  tos =  
                new TeeOutputStream(fos, System.out);
          PrintWriter      pw  =  
          new PrintWriter(new OutputStreamWriter(tos));
  
           pw.println("Testing line 1");
           pw.println("Testing line 2");
  
           pw.close();
      }
  }
  
  

 

   import java.io.* ;

    public class   CountReader
           extends Reader
    {
        Reader in = null;
        int read = 0, charCount=0, wordCount = 0,
           lineCount = 0;
        boolean whiteSpace = true;
    
    
        public CountReader (Reader r)
        {
            in = r;
        }
        
        
    /**
    * Implementation for parent's read method.  Counts 
    * chars, words, and lines.
    */
          
        public int read(char[] array, int off, int len) 
                   throws IOException
        {
            if (array == null)
                throw new IOException("Null array");
    
            // Do actual read
            read = in.read(array, off, len);
    
            // Now count
            charCount += read;  
            
            // Increment character count
            char c;
    
            for (int i=0; i < read; i++)
            {
               c = array[i];
    
               // Line count
               if (c == '\n')
                   lineCount++;
    
               // Word count
               if (Character.isWhitespace(c))
                   whiteSpace = true;
               else
               if (Character.isLetterOrDigit(c) 
                            && whiteSpace)
               {
                   wordCount++;
                   whiteSpace = false;
               }
           }
    
           return read;
        }
    
     
        public void close() throws IOException
        {
           in.close();
        }
    
    
        public int getCharCount() { return charCount; }
        public int getWordCount() { return wordCount; }
        public int getLineCount() { return lineCount; }
    
    
    
    /** Test driver */
    public static void main(
      String args[]) throws Exception
        {
           CountReader cr = new CountReader(new 
                       FileReader("CountReader.java"));
           char c[]       = new char[4096];
           int read       = 0;
     
           while ((
             read = cr.read(c, 0, c.length)) != -1)
              System.out.print(new String(c, 0, read));
    
           cr.close();
    
           System.out.println(
               "\n\nRead chars: " + cr.getCharCount() +
               "\n     words: " + cr.getWordCount() +
               "\n     lines: " + cr.getLineCount());
        }
    
    }