001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache license, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the license for the specific language governing permissions and 015 * limitations under the license. 016 */ 017package org.apache.logging.log4j.core.util; 018 019import org.apache.logging.log4j.util.Strings; 020 021/** 022 * Helps deal with integers. 023 */ 024public final class Integers { 025 026 private Integers() { 027 } 028 029 /** 030 * Parses the string argument as a signed decimal integer. 031 * 032 * @param s 033 * a {@code String} containing the {@code int} representation to parse, may be {@code null} or {@code ""} 034 * @param defaultValue 035 * the return value, use {@code defaultValue} if {@code s} is {@code null} or {@code ""} 036 * @return the integer value represented by the argument in decimal. 037 * @throws NumberFormatException 038 * if the string does not contain a parsable integer. 039 */ 040 public static int parseInt(final String s, final int defaultValue) { 041 return Strings.isEmpty(s) ? defaultValue : Integer.parseInt(s); 042 } 043 044 /** 045 * Parses the string argument as a signed decimal integer. 046 * 047 * @param s 048 * a {@code String} containing the {@code int} representation to parse, may be {@code null} or {@code ""} 049 * @return the integer value represented by the argument in decimal. 050 * @throws NumberFormatException 051 * if the string does not contain a parsable integer. 052 */ 053 public static int parseInt(final String s) { 054 return parseInt(s, 0); 055 } 056 057 /** 058 * Calculate the next power of 2, greater than or equal to x.<p> 059 * From Hacker's Delight, Chapter 3, Harry S. Warren Jr. 060 * 061 * @param x Value to round up 062 * @return The next power of 2 from x inclusive 063 */ 064 public static int ceilingNextPowerOfTwo(final int x) { 065 return 1 << (32 - Integer.numberOfLeadingZeros(x - 1)); 066 } 067}