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 package org.apache.commons.functor.example.kata.four;
18
19 import org.apache.commons.functor.UnaryFunction;
20
21 /**
22 * Converts a String value to an Integer, throwing
23 * an exception if no such conversion can be made.
24 *
25 * Trailing, non-{@link Character#isDigit digit} characters
26 * are ignored.
27 *
28 * @version $Revision: 665786 $ $Date: 2008-06-09 19:17:39 +0200 (Mon, 09 Jun 2008) $
29 * @author Rodney Waldhoff
30 */
31 public final class ToInteger implements UnaryFunction<String, Integer> {
32
33 public Integer evaluate(String str) {
34 StringBuffer buf = new StringBuffer();
35 for (int i=0;i<str.length();i++) {
36 if (Character.isDigit(str.charAt(i))) {
37 buf.append(str.charAt(i));
38 } else {
39 break;
40 }
41 }
42 try {
43 return new Integer(buf.toString());
44 } catch(NumberFormatException e) {
45 throw new NumberFormatException(str);
46 }
47 }
48
49 public static final ToInteger instance() {
50 return INSTANCE;
51 }
52
53 private static final ToInteger INSTANCE = new ToInteger();
54 }