Java - StreamTokenizer toString() method

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Description

The Java StreamTokenizer toString() method returns the string representation of the current stream token and the line number it occurs on.

If the flag argument is false, then C-style comments are not treated specially.

Declaration

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

public String toString()

Parameters

NA

Return Value

This method returns a string representation of the token.

Exception

NA

Example - Usage of StreamTokenizer toString() method

The following example shows the usage of StreamTokenizer toString() method.

StreamTokenizerDemo.java

package com.tutorialspoint;

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStreamReader;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Reader;
import java.io.StreamTokenizer;

public class StreamTokenizerDemo {
   public static void main(String[] args) {
      String text = "Hello. This is a text \n 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);

         // 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.toString());
                  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();
      }
   }
}

Output

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

Word: Token[AHello.], line 1
Word: Token[This], line 1
Word: Token[is], line 1
Word: Token[a], line 1
Word: Token[text], line 1
Word: Token[that], line 2
Word: Token[will], line 2
Word: Token[be], line 2
Word: Token[split], line 2
Word: Token[into], line 2
Word: Token[tokens.], line 2
Number: 1.0
+ encountered.
Number: 1.0
= encountered.
Number: 2.0
End of File encountered.

Example - Using toString() with word and number tokens

The following example shows the usage of StreamTokenizer toString() method.

StreamTokenizerDemo.java

package com.tutorialspoint;

import java.io.IOException;
import java.io.Reader;
import java.io.StreamTokenizer;
import java.io.StringReader;

public class StreamTokenizerDemo {
   public static void main(String[] args) throws IOException {
      String input = "Java 100";

      Reader reader = new StringReader(input);
      StreamTokenizer tokenizer = new StreamTokenizer(reader);

      tokenizer.parseNumbers(); // Enable number parsing
      tokenizer.wordChars('a', 'z');
      tokenizer.wordChars('A', 'Z');

      System.out.println("Tokens:");
      while (tokenizer.nextToken() != StreamTokenizer.TT_EOF) {
         System.out.println(tokenizer.toString());
      }
   }
}

Output

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

Token[word='Java', line=1]
Token[n=100.0, line=1]

Explanation

• First token is a word (Java), second is a number (100).

• toString() provides the value and the line number.

Example - Using toString() with punctuation (ordinary characters)

The following example shows the usage of StreamTokenizer toString() method.

StreamTokenizerDemo.java

package com.tutorialspoint;

import java.io.IOException;
import java.io.Reader;
import java.io.StreamTokenizer;
import java.io.StringReader;

public class StreamTokenizerDemo {
   public static void main(String[] args) throws IOException {
      String input = "a + b";

      Reader reader = new StringReader(input);
      StreamTokenizer tokenizer = new StreamTokenizer(reader);

      tokenizer.wordChars('a', 'z');
      tokenizer.ordinaryChar('+'); // Treat '+' as a token

      System.out.println("Tokens:");
      while (tokenizer.nextToken() != StreamTokenizer.TT_EOF) {
         System.out.println(tokenizer.toString());
      }
   }
}

Output

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

Tokens:
Token[a], line 1
Token['+'], line 1
Token[b], line 1

Explanation

• The + symbol is treated as a separate token.

• toString() shows that it's a char token and on which line it was found.