Presents your 
JAVA E-NEWSLETTER for October 3, 2002

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EXPAND GLOBS IN JAVA

While the use of regular expressions has grown in programming, the use
of glob expressions has declined. However, the Jakarta Original 
Reusable Objects (ORO) package contains a GlobCompiler for handling globs.

Globbing is the oddly named but well-known DOS/UNIX method for using
wildcards such as * to signify many files. For example, d*.bat refers 
to all batch files starting with a d, and *virus.exe refers to all 
executable files with a name ending with virus.exe.

The Jakarta ORO implements the globbing functionality by translating 
the glob language to a regular expression, so using the globbing system is
exactly the same as using a regular expression in ORO. Here's an example:

import org.apache.oro.text.*;
import org.apache.oro.text.regex.*;

public class GlobTest {

    static public void main(String[] args) throws Exception {
        GlobCompiler compiler = new GlobCompiler();
        Pattern pattern = compiler.compile("*.exe");
        PatternMatcher matcher = new Perl5Matcher();
        if(matcher.matches("foo.exe", pattern)) {
            System.err.println("foo.exe matches");
        }
        if(matcher.matches("exe.bar", pattern)) {
            System.err.println("exe.bar");
        }
    }

}

The PatternMatcher used is a Perl5Matcher because the glob pattern is
translated to Perl 5 syntax. The glob happily matches foo.exe, but it 
won't match exe.bar, so the only output is the string foo.exe matches.

Globbing is a nice feature to add to a user interface, especially if
it's a command-line interface. Few users are ready to enter regular
expressions, but many are happy to deal with simple globs.

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