How to use

emptyEnumeration

method

in

java.util.Collections

  @Override
  public Enumeration<String> getInitParameterNames() {
    return Collections.emptyEnumeration();
  }
};

public Enumeration<Permission> elements() {
  return Collections.emptyEnumeration();
}

@Override
public Enumeration<URL> findResources(String name) throws IOException {
  return Collections.emptyEnumeration();
}

/**
 * Finds an enumeration of URLs for the resource with the specified name.
 * This implementation just returns an empty {@code Enumeration}; it should
 * be overridden in subclasses.
 *
 * @param resName
 *            the name of the resource to find.
 * @return an enumeration of {@code URL} objects for the requested resource.
 * @throws IOException
 *             if an I/O error occurs.
 */
@SuppressWarnings( {
    "unchecked", "unused"
})
protected Enumeration<URL> findResources(String resName) throws IOException {
  return Collections.emptyEnumeration();
}

/**
 * Returns an enumeration of the dependencies of this target.
 *
 * @return an enumeration of the dependencies of this target (enumeration of String)
 */
public Enumeration<String> getDependencies() {
  return dependencies == null ? Collections.emptyEnumeration()
    : Collections.enumeration(dependencies);
}

/**
 * Returns an enumeration of all child wrappers.
 * @return an enumeration of the child wrappers.
 * @since Ant 1.6
 */
public synchronized Enumeration<RuntimeConfigurable> getChildren() {
  return (children == null) ? Collections.emptyEnumeration()
    : Collections.enumeration(children);
}

@Override
public Enumeration<URL> getResources(String name) throws IOException {
  if (isMasked(name)) return Collections.emptyEnumeration();
  return super.getResources(name);
}

@Override
public Enumeration<String> getAttributeNamesInScope(int scope) {
  switch (scope) {
    case PAGE_SCOPE:
      return getAttributeNames();
    case REQUEST_SCOPE:
      return this.request.getAttributeNames();
    case SESSION_SCOPE:
      HttpSession session = this.request.getSession(false);
      return (session != null ? session.getAttributeNames() : Collections.emptyEnumeration());
    case APPLICATION_SCOPE:
      return this.servletContext.getAttributeNames();
    default:
      throw new IllegalArgumentException("Invalid scope: " + scope);
  }
}

  @Override
  public Enumeration<String> getInitParameterNames()
  {
    final Map<String, String> params = WebXmlUtils.getFilterInitParams( webXmlDoc, filterName );
    if ( params == null || params.isEmpty() )
    {
      return Collections.emptyEnumeration();
    }
    return Collections.enumeration( params.keySet() );
  }
} );

public Enumeration<Permission> elements() {
  return added ? Collections.enumeration(getSingletonCollection()) : Collections.emptyEnumeration();
}

@Override
public Enumeration<String> getAttributeNamesInScope(int scope) {
  switch (scope) {
    case PAGE_SCOPE:
      return getAttributeNames();
    case REQUEST_SCOPE:
      return this.request.getAttributeNames();
    case SESSION_SCOPE:
      HttpSession session = this.request.getSession(false);
      return (session != null ? session.getAttributeNames() : Collections.emptyEnumeration());
    case APPLICATION_SCOPE:
      return this.servletContext.getAttributeNames();
    default:
      throw new IllegalArgumentException("Invalid scope: " + scope);
  }
}

@Override
public Enumeration<String> getHeaders(String name)
{
  for (Map.Entry<String, Collection<String>> entry : headers.asMap().entrySet()) {
    if (entry.getKey().equalsIgnoreCase(name)) {
      return enumeration(entry.getValue());
    }
  }
  return emptyEnumeration();
}

base = Collections.emptyEnumeration();

  @Override
  public Enumeration<String> getInitParameterNames() {
    return Collections.emptyEnumeration();
  }
}

} else {
  keyStore.load(null, null);
  enumeration = Collections.emptyEnumeration();

@Override
public Enumeration<String> getKeys() {
  return Collections.emptyEnumeration();
}

assertFalse(immutability.test(new AtomicLong()));
assertTrue(immutability.test(null));
assertTrue(immutability.test(Collections.emptyEnumeration()));
assertTrue(immutability.test(Collections.emptyIterator()));
assertTrue(immutability.test(Collections.emptyList()));

@Override
public Enumeration<String> getHeaders(String name) {
 List<String> headerValues = httpHeaders.get(name);
 if (headerValues == null || headerValues.isEmpty()) {
  return Collections.emptyEnumeration();
 }
 return Collections.enumeration(headerValues);
}

@Override
public Enumeration<String> getHeaderNames() {
  if (request.getMultiValueHeaders() == null) {
    return Collections.emptyEnumeration();
  }
  return Collections.enumeration(request.getMultiValueHeaders().keySet());
}

@Override
public Enumeration<String> getHeaders(String s) {
  if (request.getMultiValueHeaders() == null || request.getMultiValueHeaders().get(s) == null) {
    return Collections.emptyEnumeration();
  }
  return Collections.enumeration(request.getMultiValueHeaders().get(s));
}