Read file content to StringBuffer String object

import java.io.*;

public class FileSpace {

    private FileInputStream in;

    public FileSpace(String filename) {
        in = new FileInputStream(filename);
    }

    public String readWord() {
        int c;
        StringBuffer buf = new StringBuffer();

        do {
            c = in.read();
            if (Character.isSpace((char)c))
                return buf.toString();
            else
                buf.append((char)c);
        } while (c != -1);

	return buf.toString();
    }
}