Java.io.StreamTokenizer.commentChar() Method

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Description

The java.io.StreamTokenizer.commentChar(int ch) method specifies that the character argument starts a single-line comment. All characters from the comment character to the end of the line are ignored by this stream tokenizer. Any other attribute settings for the specified character are cleared.

Declaration

Following is the declaration for java.io.StreamTokenizer.commentChar() method.

public void commentChar(int ch)

Parameters

ch − The character.

Return Value

This method does not return a value.

Exception

NA

Example

The following example shows the usage of java.io.StreamTokenizer.commentChar() method.

package com.tutorialspoint;

import java.io.*;

public class StreamTokenizerDemo {
   public static void main(String[] args) {
      String text = "Hello. This is a text that will be split into tokens. " 
         + " 1 + 1 = 2";
      
      try {
         // create a new file with an ObjectOutputStream
         FileOutputStream out = new FileOutputStream("test.txt");
         ObjectOutputStream oout = new ObjectOutputStream(out);

         // write something in the file
         oout.writeUTF(text);
         oout.flush();

         // create an ObjectInputStream for the file we created before
         ObjectInputStream ois = new ObjectInputStream(new FileInputStream("test.txt"));

         // create a new tokenizer
         Reader r = new BufferedReader(new InputStreamReader(ois));
         StreamTokenizer st = new StreamTokenizer(r);

         // set character "a" as a commentChar
         st.commentChar('a');

         // print the stream tokens
         boolean eof = false;
         
         do {
            int token = st.nextToken();
            
            switch (token) {
               case StreamTokenizer.TT_EOF:
                  System.out.println("End of File encountered.");
                  eof = true;
                  break;
                  
               case StreamTokenizer.TT_EOL:
                  System.out.println("End of Line encountered.");
                  break;
                  
               case StreamTokenizer.TT_WORD:
                  System.out.println("Word: " + st.sval);
                  break;
                  
               case StreamTokenizer.TT_NUMBER:
                  System.out.println("Number: " + st.nval);
                  break;
                  
               default:
                  System.out.println((char) token + " encountered.");
                  
                  if (token == '!') {
                     eof = true;
                  }
            }
         } while (!eof);

      } catch (Exception ex) {
         ex.printStackTrace();
      }
   }
}

Let us compile and run the above program, this will produce the following result −

< encountered.
Word: Hello.
Word: This
Word: is
End of File encountered.