---

RTSI.java

package util;

import java.io.File;
import java.io.IOException;
import java.net.JarURLConnection;
import java.net.URL;
import java.util.Enumeration;
import java.util.Vector;
import java.util.jar.JarFile;
import java.util.zip.ZipEntry;

public class RTSI {


    public static void find(String tosubclassname) {
        try {
            Class tosubclass = Class.forName(tosubclassname);
            Package [] pcks = Package.getPackages();
            for (int i=0;i<pcks.length;i++) {
                find(pcks[i].getName(),tosubclass);
            }
        } catch (ClassNotFoundException ex) {
            System.err.println("Class "+tosubclassname+" not found!");
        }
    }

    public static void find(String pckname, String tosubclassname) {
        try {
            Class tosubclass = Class.forName(tosubclassname);
            find(pckname,tosubclass);
        } catch (ClassNotFoundException ex) {
            System.err.println("Class "+tosubclassname+" not found!");
        }
    }

    public static void find(String pckgname, Class tosubclass) {
        Vector s = findnames(pckgname, tosubclass);

        for(int i = 0; i < s.size(); i++)
            System.out.println(s.get(i));
    }


    public static Vector findnames(String pckgname, Class tosubclass) {
    Vector v = new Vector();        
        // Code from JWhich
        // ======
        // Translate the package name into an absolute path
    String name = new String(pckgname);
    if (!name.startsWith("/")) {
        name = "/" + name;
    }   
    name = name.replace('.','/');

        // Get a File object for the package
        URL url = RTSI.class.getResource(name);
        // URL url = tosubclass.getResource(name);
        // URL url = ClassLoader.getSystemClassLoader().getResource(name);
        //System.out.println(name+"->"+url);

        // Happens only if the jar file is not well constructed, i.e.
        // if the directories do not appear alone in the jar file like here:
        // 
        //          meta-inf/
        //          meta-inf/manifest.mf
        //          commands/                  <== IMPORTANT
        //          commands/Command.class
        //          commands/DoorClose.class
        //          commands/DoorLock.class
        //          commands/DoorOpen.class
        //          commands/LightOff.class
        //          commands/LightOn.class
        //          RTSI.class
        //
        if (url==null) return null;

        File directory = new File(url.getFile());

        // New code
        // ======
        if (directory.exists()) {
            // Get the list of the files contained in the package
            String [] files = directory.list();
            for (int i=0;i<files.length;i++) {
                
                // we are only interested in .class files
                if (files[i].endsWith(".class")) {
                    // removes the .class extension
                    String classname = files[i].substring(0,files[i].length()-6);
                    try {
                        // Try to create an instance of the object
                        Object o = Class.forName(pckgname+"."+classname).newInstance();
                        if (tosubclass.isInstance(o)) {
                //System.out.println(classname);
                            v.add(classname);
                        }
                    } catch (ClassNotFoundException cnfex) {
                        System.err.println(cnfex);
                    } catch (InstantiationException iex) {
                        // We try to instanciate an interface
                        // or an object that does not have a 
                        // default constructor
                    } catch (IllegalAccessException iaex) {
                        // The class is not public
                    }
                }
            }
        } else {
            try {
                // It does not work with the filesystem: we must
                // be in the case of a package contained in a jar file.
                JarURLConnection conn = (JarURLConnection)url.openConnection();
                String starts = conn.getEntryName();
                JarFile jfile = conn.getJarFile();
                Enumeration e = jfile.entries();
                while (e.hasMoreElements()) {
                    ZipEntry entry = (ZipEntry)e.nextElement();
                    String entryname = entry.getName();
                    if (entryname.startsWith(starts)
                        &&(entryname.lastIndexOf('/')<=starts.length())
                        &&entryname.endsWith(".class")) {
                        String classname = entryname.substring(0,entryname.length()-6);
                        if (classname.startsWith("/")) 
                            classname = classname.substring(1);
                        classname = classname.replace('/','.');
                        try {
                            // Try to create an instance of the object
                            Object o = Class.forName(classname).newInstance();
                            if (tosubclass.isInstance(o)) {
                    //System.out.println(classname.substring(classname.lastIndexOf('.')+1));
                    v.add(classname.substring(classname.lastIndexOf('.')+1));
                            }
                        } catch (ClassNotFoundException cnfex) {
                            System.err.println(cnfex);
                        } catch (InstantiationException iex) {
                            // We try to instanciate an interface
                            // or an object that does not have a 
                            // default constructor
                        } catch (IllegalAccessException iaex) {
                            // The class is not public
                        }
                    }
                }
            } catch (IOException ioex) {
                System.err.println(ioex);
            }   
        }
    
    return v;
    }
    
    public static void main(String []args) {
        if (args.length==2) {
            find(args[0],args[1]);
        } else {
            if (args.length==1) {
                find(args[0]);
            } else {
                System.out.println("Usage: java RTSI [<package>] <subclass>");
            }
        }
    }
}// RTSI

---