1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18 package org.apache.commons.jocl;
19
20 import java.lang.reflect.Constructor;
21 import java.lang.reflect.InvocationTargetException;
22
23 /**
24 * Miscellaneous {@link Constructor} related utility functions.
25 *
26 * @author Rodney Waldhoff
27 * @version $Revision: 479137 $ $Date: 2006-11-25 08:51:48 -0700 (Sat, 25 Nov 2006) $
28 */
29 public class ConstructorUtil {
30 /**
31 * Returns a {@link Constructor} for the given method signature, or <tt>null</tt>
32 * if no such <tt>Constructor</tt> can be found.
33 *
34 * @param type the (non-<tt>null</tt>) type of {@link Object} the returned {@link Constructor} should create
35 * @param argTypes a non-<tt>null</tt> array of types describing the parameters to the {@link Constructor}.
36 * @return a {@link Constructor} for the given method signature, or <tt>null</tt>
37 * if no such <tt>Constructor</tt> can be found.
38 * @see #invokeConstructor
39 */
40 public static Constructor getConstructor(Class type, Class[] argTypes) {
41 if(null == type || null == argTypes) {
42 throw new NullPointerException();
43 }
44 Constructor ctor = null;
45 try {
46 ctor = type.getConstructor(argTypes);
47 } catch(Exception e) {
48 ctor = null;
49 }
50 if(null == ctor) {
51 // no directly declared matching constructor,
52 // look for something that will work
53 // XXX this should really be more careful to
54 // adhere to the jls mechanism for late binding
55 Constructor[] ctors = type.getConstructors();
56 for(int i=0;i<ctors.length;i++) {
57 Class[] paramtypes = ctors[i].getParameterTypes();
58 if(paramtypes.length == argTypes.length) {
59 boolean canuse = true;
60 for(int j=0;j<paramtypes.length;j++) {
61 if(paramtypes[j].isAssignableFrom(argTypes[j])) {
62 continue;
63 } else {
64 canuse = false;
65 break;
66 }
67 }
68 if(canuse == true) {
69 ctor = ctors[i];
70 break;
71 }
72 }
73 }
74 }
75 return ctor;
76 }
77
78 /**
79 * Creates a new instance of the specified <tt><i>type</i></tt>
80 * using a {@link Constructor} described by the given parameter types
81 * and values.
82 *
83 * @param type the type of {@link Object} to be created
84 * @param argTypes a non-<tt>null</tt> array of types describing the parameters to the {@link Constructor}.
85 * @param argValues a non-<tt>null</tt> array containing the values of the parameters to the {@link Constructor}.
86 * @return a new instance of the specified <tt><i>type</i></tt>
87 * using a {@link Constructor} described by the given parameter types
88 * and values.
89 * @exception InstantiationException
90 * @exception IllegalAccessException
91 * @exception InvocationTargetException
92 */
93 public static Object invokeConstructor(Class type, Class[] argTypes, Object[] argValues) throws InstantiationException, IllegalAccessException, InvocationTargetException {
94 return ConstructorUtil.getConstructor(type,argTypes).newInstance(argValues);
95 }
96 }
97
98
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