StringWriter

import java.io.IOException;
import java.io.StringWriter;
/*from   j  a  v  a 2 s  . c o m*/
public class Main {
  public static void main(String args[]) throws IOException {
    StringWriter outStream = new StringWriter();
    String s = "This is a test from j a va2s.com.";
    for (int i = 0; i < s.length(); ++i)
      outStream.write(s.charAt(i));
    System.out.println("outstream: " + outStream);
    System.out.println("size: " + outStream.toString().length());
  }
}

outstream: This is a test from j a va2s.com.
size: 33

import java.io.StreamTokenizer;
import java.io.StringReader;
//from j  a  va2 s .  c o m
public class Main {
  public static void main(String[] args) throws Exception{
    StringReader reader = new StringReader("this is a test");

    int wordCount = 0;
    StreamTokenizer streamTokenizer = new StreamTokenizer(reader);

    while (streamTokenizer.nextToken() != StreamTokenizer.TT_EOF) {
      if (streamTokenizer.ttype == StreamTokenizer.TT_WORD)
        wordCount++;
    }
    System.out.println("Number of words in file: " + wordCount);
  }
}