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 }