1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one 3 * or more contributor license agreements. See the NOTICE file 4 * distributed with this work for additional information 5 * regarding copyright ownership. The ASF licenses this file 6 * to you under the Apache License, Version 2.0 (the 7 * "License"); you may not use this file except in compliance 8 * with the License. You may obtain a copy of the License at 9 * 10 * http://www.apache.org/licenses/LICENSE-2.0 11 * 12 * Unless required by applicable law or agreed to in writing, 13 * software distributed under the License is distributed on an 14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 15 * KIND, either express or implied. See the License for the 16 * specific language governing permissions and limitations 17 * under the License. 18 * 19 */ 20 package org.apache.mina.util; 21 22 /** 23 * Provides methods to check preconditions. 24 * 25 * @author <a href="http://mina.apache.org">Apache MINA Project</a> 26 */ 27 public class Assert { 28 /** 29 * This class is not intended to be instantiated! It has no state and 30 * provides only static methods 31 */ 32 private Assert() { 33 } 34 35 /** 36 * Returns <code>value</code> if it is not <code>null</code>. Otherwise a 37 * {@link IllegalArgumentException} will be thrown, the given 38 * <code>parameterName</code> is included in the Message. Eg. <br> 39 * <br> 40 * <b>Example:</b> 41 * If <code>null</code> will be passed, the message of the exception is <i>"Parameter >value< must not be null !"</i> 42 * <pre> 43 * public void myMethod(Integer value){ 44 * <b>assertNotNull(value,"value");</b> 45 * ... 46 * } 47 * </pre> 48 * @param <T> 49 * Type of the value 50 * @param value 51 * the value to check 52 * @param parameterName 53 * name of the parameter to be included in a possible 54 * {@link IllegalArgumentException} 55 * @return parameter <code>value</code> 56 * @exception IllegalArgumentException if <code>value==null</code> 57 */ 58 public static <T> T assertNotNull(T value, String parameterName) { 59 if (parameterName == null) { 60 throw new IllegalArgumentException("You must provide a parameter name!"); 61 } 62 63 if (value == null) { 64 throw new IllegalArgumentException("Parameter >" + parameterName + "< must not be null!"); 65 } 66 67 return value; 68 } 69 }