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.logging.log4j.core.util;
18
19 import org.apache.logging.log4j.util.Strings;
20
21 /**
22 * Helps deal with integers.
23 */
24 public final class Integers {
25
26 private static final int BITS_PER_INT = 32;
27
28 private Integers() {
29 }
30
31 /**
32 * Parses the string argument as a signed decimal integer.
33 *
34 * @param s a {@code String} containing the {@code int} representation to parse, may be {@code null} or {@code ""}
35 * @param defaultValue the return value, use {@code defaultValue} if {@code s} is {@code null} or {@code ""}
36 * @return the integer value represented by the argument in decimal.
37 * @throws NumberFormatException if the string does not contain a parsable integer.
38 */
39 public static int parseInt(final String s, final int defaultValue) {
40 return Strings.isEmpty(s) ? defaultValue : Integer.parseInt(s);
41 }
42
43 /**
44 * Parses the string argument as a signed decimal integer.
45 *
46 * @param s a {@code String} containing the {@code int} representation to parse, may be {@code null} or {@code ""}
47 * @return the integer value represented by the argument in decimal.
48 * @throws NumberFormatException if the string does not contain a parsable integer.
49 */
50 public static int parseInt(final String s) {
51 return parseInt(s, 0);
52 }
53
54 /**
55 * Calculate the next power of 2, greater than or equal to x.
56 * <p>
57 * From Hacker's Delight, Chapter 3, Harry S. Warren Jr.
58 *
59 * @param x Value to round up
60 * @return The next power of 2 from x inclusive
61 */
62 public static int ceilingNextPowerOfTwo(final int x) {
63 return 1 << (BITS_PER_INT - Integer.numberOfLeadingZeros(x - 1));
64 }
65 }