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 }