1. /*
  2. * Copyright 2003-2004 The Apache Software Foundation
  3. *
  4. * Licensed under the Apache License, Version 2.0 (the "License");
  5. * you may not use this file except in compliance with the License.
  6. * You may obtain a copy of the License at
  7. *
  8. * http://www.apache.org/licenses/LICENSE-2.0
  9. *
  10. * Unless required by applicable law or agreed to in writing, software
  11. * distributed under the License is distributed on an "AS IS" BASIS,
  12. * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13. * See the License for the specific language governing permissions and
  14. * limitations under the License.
  15. */
  16. package org.apache.commons.collections;
  17. /**
  18. * Marker interface for collections, maps and iterators that are unmodifiable.
  19. * <p>
  20. * This interface enables testing such as:
  21. * <pre>
  22. * if (coll instanceof Unmodifiable) {
  23. * coll = new ArrayList(coll);
  24. * }
  25. * // now we know coll is modifiable
  26. * </pre>
  27. * Of course all this only works if you use the Unmodifiable classes defined
  28. * in this library. If you use the JDK unmodifiable class via java util Collections
  29. * then the interface won't be there.
  30. *
  31. * @since Commons Collections 3.0
  32. * @version $Revision: 1.4 $ $Date: 2004/02/18 01:15:42 $
  33. *
  34. * @author Stephen Colebourne
  35. */
  36. public interface Unmodifiable {
  37. // marker interface - no methods to implement
  38. }