Currently the CertificateUsage only provides a limited set of functionalities. For example, to translate a usage string into a usage object, one has to write the following code:

  Iterator iterator = CertificateUsage.getCertificateUsages();
  while (iterator.hasNext()) {
      CertificateUsage usage = (CertificateUsage)iterator.next();
      String name = usage.toString();
      if (name.equalsIgnoreCase(usageStr)) return usage;
  }
  return null;

There are some improvements that can be done to make CertificateUsage more usable.

1. The getCertificateUsage() should return a Collection<CertificateUsage> instead of a plain Iterator. Then the above code could be simplified as follows:

  for (CertificateUsage usage : CertificateUsage.getCertificateUsages()) {
      String name = usage.toString();
      if (name.equalsIgnoreCase(usageStr)) return usage;
  }
  return null;

If backward compatibility is important, the CertificateUsage should provide a different method or a static Collection<CertificateUsage> which returns all usage objects:

  for (CertificateUsage usage : CertificateUsage.ALL_USAGES) {
      String name = usage.toString();
      if (name.equalsIgnoreCase(usageStr)) return usage;
  }
  return null;

2. The CertificateUsage should provide proper getter methods for its fields or make them public:

  for (CertificateUsage usage : CertificateUsage.ALL_USAGES) {
      String name = usage.getName();
      if (name.equalsIgnoreCase(usageStr)) return usage;
  }
  return null;

3. The CertificateUsage should provide the above code as a static method, so translating a usage string into a usage object can simply be done as follows:

  CertificateUsage usage = CertificateUsage.valueOf(usageStr);

This method can also be implemented using a HashMap<String, CertificateUsage> instead of Collection<CertificateUsage>.