Java tutorial
//package com.java2s; /* * 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. */ import java.lang.reflect.Array; import java.util.Collection; import java.util.Enumeration; import java.util.Iterator; import java.util.Map; public class Main { /** * Returns <code>true</code> iff at least one element is in both collections. * <p> * In other words, this method returns <code>true</code> iff the * {@link #intersection} of <i>coll1</i> and <i>coll2</i> is not empty. * * @param coll1 the first collection, must not be null * @param coll2 the first collection, must not be null * @return <code>true</code> iff the intersection of the collections is non-empty * @since 2.1 * @see #intersection */ public static boolean containsAny(final Collection coll1, final Collection coll2) { if (coll1.size() < coll2.size()) { for (Iterator it = coll1.iterator(); it.hasNext();) { if (coll2.contains(it.next())) { return true; } } } else { for (Iterator it = coll2.iterator(); it.hasNext();) { if (coll1.contains(it.next())) { return true; } } } return false; } /** * Gets the size of the collection/iterator specified. * <p> * This method can handles objects as follows * <ul> * <li>Collection - the collection size * <li>Map - the map size * <li>Array - the array size * <li>Iterator - the number of elements remaining in the iterator * <li>Enumeration - the number of elements remaining in the enumeration * </ul> * * @param object the object to get the size of * @return the size of the specified collection * @throws IllegalArgumentException thrown if object is not recognised or null * @since Commons Collections 3.1 */ public static int size(Object object) { int total = 0; if (object instanceof Map) { total = ((Map) object).size(); } else if (object instanceof Collection) { total = ((Collection) object).size(); } else if (object instanceof Object[]) { total = ((Object[]) object).length; } else if (object instanceof Iterator) { Iterator it = (Iterator) object; while (it.hasNext()) { total++; it.next(); } } else if (object instanceof Enumeration) { Enumeration it = (Enumeration) object; while (it.hasMoreElements()) { total++; it.nextElement(); } } else if (object == null) { throw new IllegalArgumentException("Unsupported object type: null"); } else { try { total = Array.getLength(object); } catch (IllegalArgumentException ex) { throw new IllegalArgumentException("Unsupported object type: " + object.getClass().getName()); } } return total; } }