Java tutorial
//package com.java2s; /* * $Id$ * * 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.Iterator; import java.util.Map; public class Main { /** * Determine if <code>obj2</code> exists in <code>obj1</code>. * * <table borer="1"> * <tr> * <td>Type Of obj1</td> * <td>Comparison type</td> * </tr> * <tr> * <td>null<td> * <td>always return false</td> * </tr> * <tr> * <td>Map</td> * <td>Map containsKey(obj2)</td> * </tr> * <tr> * <td>Collection</td> * <td>Collection contains(obj2)</td> * </tr> * <tr> * <td>Array</td> * <td>there's an array element (e) where e.equals(obj2)</td> * </tr> * <tr> * <td>Object</td> * <td>obj1.equals(obj2)</td> * </tr> * </table> * * * @param obj1 * @param obj2 * @return */ public static boolean contains(Object obj1, Object obj2) { if ((obj1 == null) || (obj2 == null)) { //log.debug("obj1 or obj2 are null."); return false; } if (obj1 instanceof Map) { if (((Map) obj1).containsKey(obj2)) { //log.debug("obj1 is a map and contains obj2"); return true; } } if (obj1 instanceof Iterable) { Iterator iter = ((Iterable) obj1).iterator(); while (iter.hasNext()) { Object value = iter.next(); if (obj2.equals(value) || obj2.toString().equals(value)) { return true; } } } else if (obj1.getClass().isArray()) { for (int i = 0; i < Array.getLength(obj1); i++) { Object value = null; value = Array.get(obj1, i); if (obj2.equals(value)) { //log.debug("obj1 is an array and contains obj2"); return true; } } } else if (obj1.toString().equals(obj2.toString())) { //log.debug("obj1 is an object and it's String representation equals obj2's String representation."); return true; } else if (obj1.equals(obj2)) { //log.debug("obj1 is an object and equals obj2"); return true; } //log.debug("obj1 does not contain obj2: " + obj1 + ", " + obj2); return false; } }