Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.apache.commons.collections4; /** * Marker interface for collections, maps and iterators that are unmodifiable. * <p> * This interface enables testing such as: * <pre> * if (coll instanceof Unmodifiable) { * coll = new ArrayList(coll); * } * // now we know coll is modifiable * </pre> * Of course all this only works if you use the Unmodifiable classes defined * in this library. If you use the JDK unmodifiable class via {@code java.util Collections} * then the interface won't be there. * * @since 3.0 * @version $Id: Unmodifiable.java 1477779 2013-04-30 18:55:24Z tn $ */ public interface Unmodifiable { // marker interface - no methods to implement }