Compile error help please ...

Question

I was reading the article on RE (http://developer.java.sun.com/developer/technicalArticles/releases/1.4regex/) to try to get a better understanding of regular expression use in Java. When I try to compile
the following:
* Prints out the comments found in a .java file.
import java.util.regex.*;
import java.io.*;
import java.nio.*;
import java.nio.charset.*;
import java.nio.channels.*;
public class CharBufferEx {
    public static void main(String[] args) throws Exception {
        // Create a pattern to match comments
        Pattern p =
            Pattern.compile("//.*$", Pattern.MULTILINE);
        // Get a Channel for the source file
        File f = new File(" Replacement.java ");
        FileInputStream fis = new FileInputStream(f);
        FileChannel fc = fis.getChannel();
        // Get a CharBuffer from the source file
        ByteBuffer bb =
            fc.map(FileChannel.MAP_RO, 0, (int)fc.size());
        Charset cs = Charset.forName("8859_1");
        CharsetDecoder cd = cs.newDecoder();
        CharBuffer cb = cd.decode(bb);
        // Run some matches
        Matcher m = p.matcher(cb);
        while (m.find())
            System.out.println("Found comment: "+m.group());
} I get the following error:
CharBufferEx.java:23: cannot resolve symbol
symbol  : variable MAP_RO
location: class java.nio.channels.FileChannel
            fc.map(FileChannel.MAP_RO, 0, (int)fc.size());
                              ^
1 errorAny ideas on what is wrong?
Thanks.
SA
:)

Answer 1

Let me be more clear. Don't guess at what it means, tell me what its data type is. Post some documentation about it. The compiler is telling you there's no such thing, so what you need to do is figure out why it thinks so. Think like the compiler. If you had to go open up a class file to find FileChannel.MAP_RO, what class file would it be, and what would you find? Or, does it exist at all?