Android examples for java.util:Collection Find
Find the common element type of the given Collection, if any.
/*/*w w w. ja v a 2s .co m*/ * Copyright 2002-2014 the original author or authors. * * Licensed 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 com.book2s; import java.util.*; public class Main { public static void main(String[] argv) { Collection collection = java.util.Arrays.asList("asdf", "book2s.com"); System.out.println(findCommonElementType(collection)); } /** * Find the common element type of the given Collection, if any. * @param collection the Collection to check * @return the common element type, or {@code null} if no clear * common type has been found (or the collection was empty) */ public static Class<?> findCommonElementType(Collection<?> collection) { if (isEmpty(collection)) { return null; } Class<?> candidate = null; for (Object val : collection) { if (val != null) { if (candidate == null) { candidate = val.getClass(); } else if (candidate != val.getClass()) { return null; } } } return candidate; } public static boolean isEmpty(Collection<?> collection) { return (collection == null || collection.isEmpty()); } }