ClassFinder {
  {{

    static Set predefined; //class name only
    static Set packageNames;
    static ClassFinder self;

    static {
      self = new ClassFinder();
      predefined = new HashSet();
      packageNames = new HashSet();

      // add primitive types
      // primitive types aren't really classes...
      predefined.add("int");
      predefined.add("float");
      predefined.add("boolean");
      predefined.add("short");
      predefined.add("byte");
      predefined.add("long");
      predefined.add("double");
      predefined.add("char");

      packageNames.add("java.lang");
      packageNames.add("edu.neu.ccs.demeter");
    }

    static void addClass(String className) {
      predefined.add(className);
    }

    static void removeClass(String className) {
      predefined.remove(className);
    }

    static void addPackage(String packageName) {
      packageNames.add(packageName);
    }

    static String combine(String packageName, String className) {
      if ((packageName==null) || packageName.equals("")) return className;
      return packageName + "." + className;
    }

    static boolean classExist(String partialClassName) {
      if (classExistLocal(partialClassName)) return true;
      for (Iterator iter = packageNames.iterator(); iter.hasNext(); ) {
        if (classExistGlobal((String)iter.next(), partialClassName)) return true;
      }
      return false;
    }

    static boolean classExistLocal(String partialClassName) {
      if (predefined.contains(partialClassName)) return true;
      else return false;
    }

    static boolean classExistGlobal(String packageName, String className) {
      if (classExistGlobal(combine(packageName, className))) {
        addClass(className);
        return true;
      } else return false;
    }

    static boolean classExistGlobal(String fullClassName) {
      try {
        self.loadClass(fullClassName, true);
        return true;
      } catch (ClassNotFoundException cnfe) {
        return false;
      }        
    }
  }}
}