content: /*
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to You under the Apache License, Version 2.0
   * (the "License"); you may not use this file except in compliance with
   * the License.  You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package io.arivera.oss.embedded.rabbitmq.apache.commons.lang3;
  
  import java.io.File;
  
  /**
   * <p>
   * Helpers for {@code java.lang.System}.
   * </p>
   * <p>
   * If a system property cannot be read due to security restrictions, the corresponding field in this class will be set
   * to {@code null} and a message will be written to {@code System.err}.
   * </p>
   * <p>
   * #ThreadSafe#
   * </p>
   *
   * @since 1.0
   */
  @SuppressWarnings("all")
  public class SystemUtils {
  
      /**
       * The prefix String for all Windows OS.
       */
      private static final String OS_NAME_WINDOWS_PREFIX = "Windows";
  
      // System property constants
      // -----------------------------------------------------------------------
      // These MUST be declared first. Other constants depend on this.
  
      /**
       * The System property key for the user home directory.
       */
      private static final String USER_HOME_KEY = "user.home";
  
      /**
       * The System property key for the user directory.
       */
      private static final String USER_DIR_KEY = "user.dir";
  
      /**
       * The System property key for the Java IO temporary directory.
       */
      private static final String JAVA_IO_TMPDIR_KEY = "java.io.tmpdir";
  
      /**
       * The System property key for the Java home directory.
       */
      private static final String JAVA_HOME_KEY = "java.home";
  
      /**
       * <p>
       * The {@code awt.toolkit} System Property.
       * </p>
       * <p>
       * Holds a class name, on Windows XP this is {@code sun.awt.windows.WToolkit}.
       * </p>
       * <p>
       * <b>On platforms without a GUI, this value is {@code null}.</b>
       * </p>
       * <p>
       * Defaults to {@code null} if the runtime does not have security access to read this property or the property does
       * not exist.
       * </p>
       * <p>
       * This value is initialized when the class is loaded. If {@link System#setProperty(String,String)} or
       * {@link System#setProperties(java.util.Properties)} is called after this class is loaded, the value will be out of
       * sync with that System property.
       * </p>
       *
       * @since 2.1
       */
      public static final String AWT_TOOLKIT = getSystemProperty("awt.toolkit");
  
      /**
       * <p>
       * The {@code file.encoding} System Property.
       * </p>
       * <p>
       * File encoding, such as {@code Cp1252}.
       * </p>
       * <p>
       * Defaults to {@code null} if the runtime does not have security access to read this property or the property does
       * not exist.
       * </p>
       * <p>
       * This value is initialized when the class is loaded. If {@link System#setProperty(String,String)} or
       * {@link System#setProperties(java.util.Properties)} is called after this class is loaded, the value will be out of
       * sync with that System property.
       * </p>
       *
       * @since 2.0
       * @since Java 1.2
       */
      public static final String FILE_ENCODING = getSystemProperty("file.encoding");
  
      /**
       * <p>
       * The {@code file.separator} System Property.
       * The file separator is:
       * </p>
       * <ul>
       * <li>{@code "/"} on UNIX</li>
       * <li>{@code "\"} on Windows.</li>
       * </ul>
       *
       * <p>
       * Defaults to {@code null} if the runtime does not have security access to read this property or the property does
       * not exist.
       * </p>
       * <p>
       * This value is initialized when the class is loaded. If {@link System#setProperty(String,String)} or
       * {@link System#setProperties(java.util.Properties)} is called after this class is loaded, the value will be out of
       * sync with that System property.
       * </p>
       *
       * @deprecated Use {@link File#separator}, since it is guaranteed to be a
       *             string containing a single character and it does not require a privilege check.
       * @since Java 1.1
       */
      @Deprecated
      public static final String FILE_SEPARATOR = getSystemProperty("file.separator");
  
      /**
       * <p>
       * The {@code java.awt.fonts} System Property.
       * </p>
       * <p>
       * Defaults to {@code null} if the runtime does not have security access to read this property or the property does
       * not exist.
       * </p>
       * <p>
       * This value is initialized when the class is loaded. If {@link System#setProperty(String,String)} or
       * {@link System#setProperties(java.util.Properties)} is called after this class is loaded, the value will be out of
       * sync with that System property.
       * </p>
       *
       * @since 2.1
       */
      public static final String JAVA_AWT_FONTS = getSystemProperty("java.awt.fonts");
  
      /**
       * <p>
       * The {@code java.awt.graphicsenv} System Property.
       * </p>
       * <p>
       * Defaults to {@code null} if the runtime does not have security access to read this property or the property does
       * not exist.
       * </p>
       * <p>
       * This value is initialized when the class is loaded. If {@link System#setProperty(String,String)} or
       * {@link System#setProperties(java.util.Properties)} is called after this class is loaded, the value will be out of
       * sync with that System property.
       * </p>
       *
       * @since 2.1
       */
      public static final String JAVA_AWT_GRAPHICSENV = getSystemProperty("java.awt.graphicsenv");
  
      /**
       * <p>
       * The {@code java.awt.headless} System Property. The value of this property is the String {@code "true"} or
       * {@code "false"}.
       * </p>
       * <p>
       * Defaults to {@code null} if the runtime does not have security access to read this property or the property does
       * not exist.
       * </p>
       * <p>
       * This value is initialized when the class is loaded. If {@link System#setProperty(String,String)} or
       * {@link System#setProperties(java.util.Properties)} is called after this class is loaded, the value will be out of
       * sync with that System property.
       * </p>
       *
       * @see #isJavaAwtHeadless()
       * @since 2.1
       * @since Java 1.4
       */
      public static final String JAVA_AWT_HEADLESS = getSystemProperty("java.awt.headless");
  
      /**
       * <p>
       * The {@code java.awt.printerjob} System Property.
       * </p>
       * <p>
       * Defaults to {@code null} if the runtime does not have security access to read this property or the property does
       * not exist.
       * </p>
       * <p>
       * This value is initialized when the class is loaded. If {@link System#setProperty(String,String)} or
       * {@link System#setProperties(java.util.Properties)} is called after this class is loaded, the value will be out of
       * sync with that System property.
       * </p>
       *
       * @since 2.1
       */
      public static final String JAVA_AWT_PRINTERJOB = getSystemProperty("java.awt.printerjob");
  
      /**
       * <p>
       * The {@code java.class.path} System Property. Java class path.
       * </p>
       * <p>
       * Defaults to {@code null} if the runtime does not have security access to read this property or the property does
       * not exist.
       * </p>
       * <p>
       * This value is initialized when the class is loaded. If {@link System#setProperty(String,String)} or
       * {@link System#setProperties(java.util.Properties)} is called after this class is loaded, the value will be out of
       * sync with that System property.
       * </p>
       *
       * @since Java 1.1
       */
      public static final String JAVA_CLASS_PATH = getSystemProperty("java.class.path");
  
      /**
       * <p>
       * The {@code java.class.version} System Property. Java class format version number.
       * </p>
       * <p>
       * Defaults to {@code null} if the runtime does not have security access to read this property or the property does
       * not exist.
       * </p>
       * <p>
       * This value is initialized when the class is loaded. If {@link System#setProperty(String,String)} or
       * {@link System#setProperties(java.util.Properties)} is called after this class is loaded, the value will be out of
       * sync with that System property.
       * </p>
       *
       * @since Java 1.1
       */
      public static final String JAVA_CLASS_VERSION = getSystemProperty("java.class.version");
  
      /**
       * <p>
       * The {@code java.compiler} System Property. Name of JIT compiler to use. First in JDK version 1.2. Not used in Sun
       * JDKs after 1.2.
       * </p>
       * <p>
       * Defaults to {@code null} if the runtime does not have security access to read this property or the property does
       * not exist.
       * </p>
       * <p>
       * This value is initialized when the class is loaded. If {@link System#setProperty(String,String)} or
       * {@link System#setProperties(java.util.Properties)} is called after this class is loaded, the value will be out of
       * sync with that System property.
       * </p>
       *
       * @since Java 1.2. Not used in Sun versions after 1.2.
       */
      public static final String JAVA_COMPILER = getSystemProperty("java.compiler");
  
      /**
       * <p>
       * The {@code java.endorsed.dirs} System Property. Path of endorsed directory or directories.
       * </p>
       * <p>
       * Defaults to {@code null} if the runtime does not have security access to read this property or the property does
       * not exist.
       * </p>
       * <p>
       * This value is initialized when the class is loaded. If {@link System#setProperty(String,String)} or
       * {@link System#setProperties(java.util.Properties)} is called after this class is loaded, the value will be out of
       * sync with that System property.
       * </p>
       *
       * @since Java 1.4
       */
      public static final String JAVA_ENDORSED_DIRS = getSystemProperty("java.endorsed.dirs");
  
      /**
       * <p>
       * The {@code java.ext.dirs} System Property. Path of extension directory or directories.
       * </p>
       * <p>
       * Defaults to {@code null} if the runtime does not have security access to read this property or the property does
       * not exist.
       * </p>
       * <p>
       * This value is initialized when the class is loaded. If {@link System#setProperty(String,String)} or
       * {@link System#setProperties(java.util.Properties)} is called after this class is loaded, the value will be out of
       * sync with that System property.
       * </p>
       *
       * @since Java 1.3
       */
      public static final String JAVA_EXT_DIRS = getSystemProperty("java.ext.dirs");
  
      /**
       * <p>
       * The {@code java.home} System Property. Java installation directory.
       * </p>
       * <p>
       * Defaults to {@code null} if the runtime does not have security access to read this property or the property does
       * not exist.
       * </p>
       * <p>
       * This value is initialized when the class is loaded. If {@link System#setProperty(String,String)} or
       * {@link System#setProperties(java.util.Properties)} is called after this class is loaded, the value will be out of
       * sync with that System property.
       * </p>
       *
       * @since Java 1.1
       */
      public static final String JAVA_HOME = getSystemProperty(JAVA_HOME_KEY);
  
      /**
       * <p>
       * The {@code java.io.tmpdir} System Property. Default temp file path.
       * </p>
       * <p>
       * Defaults to {@code null} if the runtime does not have security access to read this property or the property does
       * not exist.
       * </p>
       * <p>
       * This value is initialized when the class is loaded. If {@link System#setProperty(String,String)} or
       * {@link System#setProperties(java.util.Properties)} is called after this class is loaded, the value will be out of
       * sync with that System property.
       * </p>
       *
       * @since Java 1.2
       */
      public static final String JAVA_IO_TMPDIR = getSystemProperty(JAVA_IO_TMPDIR_KEY);
  
      /**
       * <p>
       * The {@code java.library.path} System Property. List of paths to search when loading libraries.
       * </p>
       * <p>
       * Defaults to {@code null} if the runtime does not have security access to read this property or the property does
       * not exist.
       * </p>
       * <p>
       * This value is initialized when the class is loaded. If {@link System#setProperty(String,String)} or
       * {@link System#setProperties(java.util.Properties)} is called after this class is loaded, the value will be out of
       * sync with that System property.
       * </p>
       *
       * @since Java 1.2
       */
      public static final String JAVA_LIBRARY_PATH = getSystemProperty("java.library.path");
  
      /**
       * <p>
       * The {@code java.runtime.name} System Property. Java Runtime Environment name.
       * </p>
       * <p>
       * Defaults to {@code null} if the runtime does not have security access to read this property or the property does
       * not exist.
       * </p>
       * <p>
       * This value is initialized when the class is loaded. If {@link System#setProperty(String,String)} or
       * {@link System#setProperties(java.util.Properties)} is called after this class is loaded, the value will be out of
       * sync with that System property.
       * </p>
       *
       * @since 2.0
       * @since Java 1.3
       */
      public static final String JAVA_RUNTIME_NAME = getSystemProperty("java.runtime.name");
  
      /**
       * <p>
       * The {@code java.runtime.version} System Property. Java Runtime Environment version.
       * </p>
       * <p>
       * Defaults to {@code null} if the runtime does not have security access to read this property or the property does
       * not exist.
       * </p>
       * <p>
       * This value is initialized when the class is loaded. If {@link System#setProperty(String,String)} or
       * {@link System#setProperties(java.util.Properties)} is called after this class is loaded, the value will be out of
       * sync with that System property.
       * </p>
       *
       * @since 2.0
       * @since Java 1.3
       */
      public static final String JAVA_RUNTIME_VERSION = getSystemProperty("java.runtime.version");
  
      /**
       * <p>
       * The {@code java.specification.name} System Property. Java Runtime Environment specification name.
       * </p>
       * <p>
       * Defaults to {@code null} if the runtime does not have security access to read this property or the property does
       * not exist.
       * </p>
       * <p>
       * This value is initialized when the class is loaded. If {@link System#setProperty(String,String)} or
       * {@link System#setProperties(java.util.Properties)} is called after this class is loaded, the value will be out of
       * sync with that System property.
       * </p>
       *
       * @since Java 1.2
       */
      public static final String JAVA_SPECIFICATION_NAME = getSystemProperty("java.specification.name");
  
      /**
       * <p>
       * The {@code java.specification.vendor} System Property. Java Runtime Environment specification vendor.
       * </p>
       * <p>
       * Defaults to {@code null} if the runtime does not have security access to read this property or the property does
       * not exist.
       * </p>
       * <p>
       * This value is initialized when the class is loaded. If {@link System#setProperty(String,String)} or
       * {@link System#setProperties(java.util.Properties)} is called after this class is loaded, the value will be out of
       * sync with that System property.
       * </p>
       *
       * @since Java 1.2
       */
      public static final String JAVA_SPECIFICATION_VENDOR = getSystemProperty("java.specification.vendor");
  
      /**
       * <p>
       * The {@code java.specification.version} System Property. Java Runtime Environment specification version.
       * </p>
       * <p>
       * Defaults to {@code null} if the runtime does not have security access to read this property or the property does
       * not exist.
       * </p>
       * <p>
       * This value is initialized when the class is loaded. If {@link System#setProperty(String,String)} or
       * {@link System#setProperties(java.util.Properties)} is called after this class is loaded, the value will be out of
       * sync with that System property.
       * </p>
       *
       * @since Java 1.3
       */
      public static final String JAVA_SPECIFICATION_VERSION = getSystemProperty("java.specification.version");
      private static final JavaVersion JAVA_SPECIFICATION_VERSION_AS_ENUM = JavaVersion.get(JAVA_SPECIFICATION_VERSION);
  
      /**
       * <p>
       * The {@code java.util.prefs.PreferencesFactory} System Property. A class name.
       * </p>
       * <p>
       * Defaults to {@code null} if the runtime does not have security access to read this property or the property does
       * not exist.
       * </p>
       * <p>
       * This value is initialized when the class is loaded. If {@link System#setProperty(String,String)} or
       * {@link System#setProperties(java.util.Properties)} is called after this class is loaded, the value will be out of
       * sync with that System property.
       * </p>
       *
       * @since 2.1
       * @since Java 1.4
       */
      public static final String JAVA_UTIL_PREFS_PREFERENCES_FACTORY =
          getSystemProperty("java.util.prefs.PreferencesFactory");
  
      /**
       * <p>
       * The {@code java.vendor} System Property. Java vendor-specific string.
       * </p>
       * <p>
       * Defaults to {@code null} if the runtime does not have security access to read this property or the property does
       * not exist.
       * </p>
       * <p>
       * This value is initialized when the class is loaded. If {@link System#setProperty(String,String)} or
       * {@link System#setProperties(java.util.Properties)} is called after this class is loaded, the value will be out of
       * sync with that System property.
       * </p>
       *
       * @since Java 1.1
       */
      public static final String JAVA_VENDOR = getSystemProperty("java.vendor");
  
      /**
       * <p>
       * The {@code java.vendor.url} System Property. Java vendor URL.
       * </p>
       * <p>
       * Defaults to {@code null} if the runtime does not have security access to read this property or the property does
       * not exist.
       * </p>
       * <p>
       * This value is initialized when the class is loaded. If {@link System#setProperty(String,String)} or
       * {@link System#setProperties(java.util.Properties)} is called after this class is loaded, the value will be out of
       * sync with that System property.
       * </p>
       *
       * @since Java 1.1
       */
      public static final String JAVA_VENDOR_URL = getSystemProperty("java.vendor.url");
  
      /**
       * <p>
       * The {@code java.version} System Property. Java version number.
       * </p>
       * <p>
       * Defaults to {@code null} if the runtime does not have security access to read this property or the property does
       * not exist.
       * </p>
       * <p>
       * This value is initialized when the class is loaded. If {@link System#setProperty(String,String)} or
       * {@link System#setProperties(java.util.Properties)} is called after this class is loaded, the value will be out of
       * sync with that System property.
       * </p>
       *
       * @since Java 1.1
       */
      public static final String JAVA_VERSION = getSystemProperty("java.version");
  
      /**
       * <p>
       * The {@code java.vm.info} System Property. Java Virtual Machine implementation info.
       * </p>
       * <p>
       * Defaults to {@code null} if the runtime does not have security access to read this property or the property does
       * not exist.
       * </p>
       * <p>
       * This value is initialized when the class is loaded. If {@link System#setProperty(String,String)} or
       * {@link System#setProperties(java.util.Properties)} is called after this class is loaded, the value will be out of
       * sync with that System property.
       * </p>
       *
       * @since 2.0
       * @since Java 1.2
       */
      public static final String JAVA_VM_INFO = getSystemProperty("java.vm.info");
  
      /**
       * <p>
       * The {@code java.vm.name} System Property. Java Virtual Machine implementation name.
       * </p>
       * <p>
       * Defaults to {@code null} if the runtime does not have security access to read this property or the property does
       * not exist.
       * </p>
       * <p>
       * This value is initialized when the class is loaded. If {@link System#setProperty(String,String)} or
       * {@link System#setProperties(java.util.Properties)} is called after this class is loaded, the value will be out of
       * sync with that System property.
       * </p>
       *
       * @since Java 1.2
       */
      public static final String JAVA_VM_NAME = getSystemProperty("java.vm.name");
  
      /**
       * <p>
       * The {@code java.vm.specification.name} System Property. Java Virtual Machine specification name.
       * </p>
       * <p>
       * Defaults to {@code null} if the runtime does not have security access to read this property or the property does
       * not exist.
       * </p>
       * <p>
       * This value is initialized when the class is loaded. If {@link System#setProperty(String,String)} or
       * {@link System#setProperties(java.util.Properties)} is called after this class is loaded, the value will be out of
       * sync with that System property.
       * </p>
       *
       * @since Java 1.2
       */
      public static final String JAVA_VM_SPECIFICATION_NAME = getSystemProperty("java.vm.specification.name");
  
      /**
       * <p>
       * The {@code java.vm.specification.vendor} System Property. Java Virtual Machine specification vendor.
       * </p>
       * <p>
       * Defaults to {@code null} if the runtime does not have security access to read this property or the property does
       * not exist.
       * </p>
       * <p>
       * This value is initialized when the class is loaded. If {@link System#setProperty(String,String)} or
       * {@link System#setProperties(java.util.Properties)} is called after this class is loaded, the value will be out of
       * sync with that System property.
       * </p>
       *
       * @since Java 1.2
       */
      public static final String JAVA_VM_SPECIFICATION_VENDOR = getSystemProperty("java.vm.specification.vendor");
  
      /**
       * <p>
       * The {@code java.vm.specification.version} System Property. Java Virtual Machine specification version.
       * </p>
       * <p>
       * Defaults to {@code null} if the runtime does not have security access to read this property or the property does
       * not exist.
       * </p>
       * <p>
       * This value is initialized when the class is loaded. If {@link System#setProperty(String,String)} or
       * {@link System#setProperties(java.util.Properties)} is called after this class is loaded, the value will be out of
       * sync with that System property.
       * </p>
       *
       * @since Java 1.2
       */
      public static final String JAVA_VM_SPECIFICATION_VERSION = getSystemProperty("java.vm.specification.version");
  
      /**
       * <p>
       * The {@code java.vm.vendor} System Property. Java Virtual Machine implementation vendor.
       * </p>
       * <p>
       * Defaults to {@code null} if the runtime does not have security access to read this property or the property does
       * not exist.
       * </p>
       * <p>
       * This value is initialized when the class is loaded. If {@link System#setProperty(String,String)} or
       * {@link System#setProperties(java.util.Properties)} is called after this class is loaded, the value will be out of
       * sync with that System property.
       * </p>
       *
       * @since Java 1.2
       */
      public static final String JAVA_VM_VENDOR = getSystemProperty("java.vm.vendor");
  
      /**
       * <p>
       * The {@code java.vm.version} System Property. Java Virtual Machine implementation version.
       * </p>
       * <p>
       * Defaults to {@code null} if the runtime does not have security access to read this property or the property does
       * not exist.
       * </p>
       * <p>
       * This value is initialized when the class is loaded. If {@link System#setProperty(String,String)} or
       * {@link System#setProperties(java.util.Properties)} is called after this class is loaded, the value will be out of
       * sync with that System property.
       * </p>
       *
       * @since Java 1.2
       */
      public static final String JAVA_VM_VERSION = getSystemProperty("java.vm.version");
  
      /**
       * <p>
       * The {@code line.separator} System Property. Line separator (<code>&quot;\n&quot;</code> on UNIX).
       * </p>
       * <p>
       * Defaults to {@code null} if the runtime does not have security access to read this property or the property does
       * not exist.
       * </p>
       * <p>
       * This value is initialized when the class is loaded. If {@link System#setProperty(String,String)} or
       * {@link System#setProperties(java.util.Properties)} is called after this class is loaded, the value will be out of
       * sync with that System property.
       * </p>
       *
       * @since Java 1.1
       */
      public static final String LINE_SEPARATOR = getSystemProperty("line.separator");
  
      /**
       * <p>
       * The {@code os.arch} System Property. Operating system architecture.
       * </p>
       * <p>
       * Defaults to {@code null} if the runtime does not have security access to read this property or the property does
       * not exist.
       * </p>
       * <p>
       * This value is initialized when the class is loaded. If {@link System#setProperty(String,String)} or
       * {@link System#setProperties(java.util.Properties)} is called after this class is loaded, the value will be out of
       * sync with that System property.
       * </p>
       *
       * @since Java 1.1
       */
      public static final String OS_ARCH = getSystemProperty("os.arch");
  
      /**
       * <p>
       * The {@code os.name} System Property. Operating system name.
       * </p>
       * <p>
       * Defaults to {@code null} if the runtime does not have security access to read this property or the property does
       * not exist.
       * </p>
       * <p>
       * This value is initialized when the class is loaded. If {@link System#setProperty(String,String)} or
       * {@link System#setProperties(java.util.Properties)} is called after this class is loaded, the value will be out of
       * sync with that System property.
       * </p>
       *
       * @since Java 1.1
       */
      public static final String OS_NAME = getSystemProperty("os.name");
  
      /**
       * <p>
       * The {@code os.version} System Property. Operating system version.
       * </p>
       * <p>
       * Defaults to {@code null} if the runtime does not have security access to read this property or the property does
       * not exist.
       * </p>
       * <p>
       * This value is initialized when the class is loaded. If {@link System#setProperty(String,String)} or
       * {@link System#setProperties(java.util.Properties)} is called after this class is loaded, the value will be out of
       * sync with that System property.
       * </p>
       *
       * @since Java 1.1
       */
      public static final String OS_VERSION = getSystemProperty("os.version");
  
      /**
       * <p>
       * The {@code path.separator} System Property. Path separator (<code>&quot;:&quot;</code> on UNIX).
       * </p>
       * <p>
       * Defaults to {@code null} if the runtime does not have security access to read this property or the property does
       * not exist.
       * </p>
       * <p>
       * This value is initialized when the class is loaded. If {@link System#setProperty(String,String)} or
       * {@link System#setProperties(java.util.Properties)} is called after this class is loaded, the value will be out of
       * sync with that System property.
       * </p>
       *
       * @deprecated Use {@link File#pathSeparator}, since it is guaranteed to be a
       *             string containing a single character and it does not require a privilege check.
       * @since Java 1.1
       */
      @Deprecated
      public static final String PATH_SEPARATOR = getSystemProperty("path.separator");
  
      /**
       * <p>
       * The {@code user.country} or {@code user.region} System Property. User's country code, such as {@code GB}. First
       * in Java version 1.2 as {@code user.region}. Renamed to {@code user.country} in 1.4
       * </p>
       * <p>
       * Defaults to {@code null} if the runtime does not have security access to read this property or the property does
       * not exist.
       * </p>
       * <p>
       * This value is initialized when the class is loaded. If {@link System#setProperty(String,String)} or
       * {@link System#setProperties(java.util.Properties)} is called after this class is loaded, the value will be out of
       * sync with that System property.
       * </p>
       *
       * @since 2.0
       * @since Java 1.2
       */
      public static final String USER_COUNTRY = getSystemProperty("user.country") == null ?
          getSystemProperty("user.region") : getSystemProperty("user.country");
  
      /**
       * <p>
       * The {@code user.dir} System Property. User's current working directory.
       * </p>
       * <p>
       * Defaults to {@code null} if the runtime does not have security access to read this property or the property does
       * not exist.
       * </p>
       * <p>
       * This value is initialized when the class is loaded. If {@link System#setProperty(String,String)} or
       * {@link System#setProperties(java.util.Properties)} is called after this class is loaded, the value will be out of
       * sync with that System property.
       * </p>
       *
       * @since Java 1.1
       */
      public static final String USER_DIR = getSystemProperty(USER_DIR_KEY);
  
      /**
       * <p>
       * The {@code user.home} System Property. User's home directory.
       * </p>
       * <p>
       * Defaults to {@code null} if the runtime does not have security access to read this property or the property does
       * not exist.
       * </p>
       * <p>
       * This value is initialized when the class is loaded. If {@link System#setProperty(String,String)} or
       * {@link System#setProperties(java.util.Properties)} is called after this class is loaded, the value will be out of
       * sync with that System property.
       * </p>
       *
       * @since Java 1.1
       */
      public static final String USER_HOME = getSystemProperty(USER_HOME_KEY);
  
      /**
       * <p>
       * The {@code user.language} System Property. User's language code, such as {@code "en"}.
       * </p>
       * <p>
       * Defaults to {@code null} if the runtime does not have security access to read this property or the property does
       * not exist.
       * </p>
       * <p>
       * This value is initialized when the class is loaded. If {@link System#setProperty(String,String)} or
       * {@link System#setProperties(java.util.Properties)} is called after this class is loaded, the value will be out of
       * sync with that System property.
       * </p>
       *
       * @since 2.0
       * @since Java 1.2
       */
      public static final String USER_LANGUAGE = getSystemProperty("user.language");
  
      /**
       * <p>
       * The {@code user.name} System Property. User's account name.
       * </p>
       * <p>
       * Defaults to {@code null} if the runtime does not have security access to read this property or the property does
       * not exist.
       * </p>
       * <p>
       * This value is initialized when the class is loaded. If {@link System#setProperty(String,String)} or
       * {@link System#setProperties(java.util.Properties)} is called after this class is loaded, the value will be out of
       * sync with that System property.
       * </p>
       *
       * @since Java 1.1
       */
      public static final String USER_NAME = getSystemProperty("user.name");
  
      /**
       * <p>
       * The {@code user.timezone} System Property. For example: {@code "America/Los_Angeles"}.
       * </p>
       * <p>
       * Defaults to {@code null} if the runtime does not have security access to read this property or the property does
       * not exist.
       * </p>
       * <p>
       * This value is initialized when the class is loaded. If {@link System#setProperty(String,String)} or
       * {@link System#setProperties(java.util.Properties)} is called after this class is loaded, the value will be out of
       * sync with that System property.
       * </p>
       *
       * @since 2.1
       */
      public static final String USER_TIMEZONE = getSystemProperty("user.timezone");
  
      // Java version checks
      // -----------------------------------------------------------------------
      // These MUST be declared after those above as they depend on the
      // values being set up
  
      /**
       * <p>
       * Is {@code true} if this is Java version 1.1 (also 1.1.x versions).
       * </p>
       * <p>
       * The field will return {@code false} if {@link #JAVA_VERSION} is {@code null}.
       * </p>
       */
      public static final boolean IS_JAVA_1_1 = getJavaVersionMatches("1.1");
  
      /**
       * <p>
       * Is {@code true} if this is Java version 1.2 (also 1.2.x versions).
       * </p>
       * <p>
       * The field will return {@code false} if {@link #JAVA_VERSION} is {@code null}.
       * </p>
       */
      public static final boolean IS_JAVA_1_2 = getJavaVersionMatches("1.2");
  
      /**
       * <p>
       * Is {@code true} if this is Java version 1.3 (also 1.3.x versions).
       * </p>
       * <p>
       * The field will return {@code false} if {@link #JAVA_VERSION} is {@code null}.
       * </p>
       */
      public static final boolean IS_JAVA_1_3 = getJavaVersionMatches("1.3");
  
      /**
       * <p>
       * Is {@code true} if this is Java version 1.4 (also 1.4.x versions).
       * </p>
       * <p>
       * The field will return {@code false} if {@link #JAVA_VERSION} is {@code null}.
       * </p>
       */
      public static final boolean IS_JAVA_1_4 = getJavaVersionMatches("1.4");
  
      /**
       * <p>
       * Is {@code true} if this is Java version 1.5 (also 1.5.x versions).
       * </p>
       * <p>
       * The field will return {@code false} if {@link #JAVA_VERSION} is {@code null}.
       * </p>
       */
      public static final boolean IS_JAVA_1_5 = getJavaVersionMatches("1.5");
  
      /**
       * <p>
       * Is {@code true} if this is Java version 1.6 (also 1.6.x versions).
       * </p>
       * <p>
       * The field will return {@code false} if {@link #JAVA_VERSION} is {@code null}.
       * </p>
       */
      public static final boolean IS_JAVA_1_6 = getJavaVersionMatches("1.6");
  
      /**
       * <p>
       * Is {@code true} if this is Java version 1.7 (also 1.7.x versions).
       * </p>
       * <p>
       * The field will return {@code false} if {@link #JAVA_VERSION} is {@code null}.
       * </p>
       *
       * @since 3.0
       */
      public static final boolean IS_JAVA_1_7 = getJavaVersionMatches("1.7");
  
      /**
       * <p>
       * Is {@code true} if this is Java version 1.8 (also 1.8.x versions).
       * </p>
       * <p>
       * The field will return {@code false} if {@link #JAVA_VERSION} is {@code null}.
       * </p>
       *
       * @since 3.3.2
       */
      public static final boolean IS_JAVA_1_8 = getJavaVersionMatches("1.8");
  
      /**
       * <p>
       * Is {@code true} if this is Java version 1.9 (also 1.9.x versions).
       * </p>
       * <p>
       * The field will return {@code false} if {@link #JAVA_VERSION} is {@code null}.
       * </p>
       *
       * @since 3.4
       */
      public static final boolean IS_JAVA_1_9 = getJavaVersionMatches("1.9");
  
      // Operating system checks
      // -----------------------------------------------------------------------
      // These MUST be declared after those above as they depend on the
      // values being set up
      // OS names from http://www.vamphq.com/os.html
      // Selected ones included - please advise dev@commons.apache.org
      // if you want another added or a mistake corrected
  
      /**
       * <p>
       * Is {@code true} if this is AIX.
       * </p>
       * <p>
       * The field will return {@code false} if {@code OS_NAME} is {@code null}.
       * </p>
       *
       * @since 2.0
       */
      public static final boolean IS_OS_AIX = getOSMatchesName("AIX");
  
      /**
       * <p>
       * Is {@code true} if this is HP-UX.
       * </p>
       * <p>
       * The field will return {@code false} if {@code OS_NAME} is {@code null}.
       * </p>
       *
       * @since 2.0
       */
      public static final boolean IS_OS_HP_UX = getOSMatchesName("HP-UX");
  
      /**
       * <p>
       * Is {@code true} if this is IBM OS/400.
       * </p>
       * <p>
       * The field will return {@code false} if {@code OS_NAME} is {@code null}.
       * </p>
       *
       * @since 3.3
       */
      public static final boolean IS_OS_400 = getOSMatchesName("OS/400");
  
      /**
       * <p>
       * Is {@code true} if this is Irix.
       * </p>
       * <p>
       * The field will return {@code false} if {@code OS_NAME} is {@code null}.
       * </p>
       *
       * @since 2.0
       */
      public static final boolean IS_OS_IRIX = getOSMatchesName("Irix");
  
      /**
       * <p>
       * Is {@code true} if this is Linux.
       * </p>
       * <p>
       * The field will return {@code false} if {@code OS_NAME} is {@code null}.
       * </p>
       *
       * @since 2.0
       */
      public static final boolean IS_OS_LINUX = getOSMatchesName("Linux") || getOSMatchesName("LINUX");
  
      /**
       * <p>
       * Is {@code true} if this is Mac.
       * </p>
       * <p>
       * The field will return {@code false} if {@code OS_NAME} is {@code null}.
       * </p>
       *
       * @since 2.0
       */
      public static final boolean IS_OS_MAC = getOSMatchesName("Mac");
  
      /**
       * <p>
       * Is {@code true} if this is Mac.
       * </p>
       * <p>
       * The field will return {@code false} if {@code OS_NAME} is {@code null}.
       * </p>
       *
       * @since 2.0
       */
      public static final boolean IS_OS_MAC_OSX = getOSMatchesName("Mac OS X");
  
      /**
       * <p>
       * Is {@code true} if this is Mac OS X Cheetah.
       * </p>
       * <p>
       * The field will return {@code false} if {@code OS_NAME} is {@code null}.
       * </p>
       *
       * @since 3.4
       */
      public static final boolean IS_OS_MAC_OSX_CHEETAH = getOSMatches("Mac OS X", "10.0");
  
      /**
       * <p>
       * Is {@code true} if this is Mac OS X Puma.
       * </p>
       * <p>
       * The field will return {@code false} if {@code OS_NAME} is {@code null}.
       * </p>
       *
       * @since 3.4
       */
      public static final boolean IS_OS_MAC_OSX_PUMA = getOSMatches("Mac OS X", "10.1");
  
      /**
       * <p>
       * Is {@code true} if this is Mac OS X Jaguar.
       * </p>
       * <p>
       * The field will return {@code false} if {@code OS_NAME} is {@code null}.
       * </p>
       *
       * @since 3.4
       */
      public static final boolean IS_OS_MAC_OSX_JAGUAR = getOSMatches("Mac OS X", "10.2");
  
      /**
       * <p>
       * Is {@code true} if this is Mac OS X Panther.
       * </p>
       * <p>
       * The field will return {@code false} if {@code OS_NAME} is {@code null}.
       * </p>
       *
       * @since 3.4
       */
      public static final boolean IS_OS_MAC_OSX_PANTHER = getOSMatches("Mac OS X", "10.3");
  
      /**
       * <p>
       * Is {@code true} if this is Mac OS X Tiger.
       * </p>
       * <p>
       * The field will return {@code false} if {@code OS_NAME} is {@code null}.
       * </p>
       *
       * @since 3.4
       */
      public static final boolean IS_OS_MAC_OSX_TIGER = getOSMatches("Mac OS X", "10.4");
  
      /**
       * <p>
       * Is {@code true} if this is Mac OS X Leopard.
       * </p>
       * <p>
       * The field will return {@code false} if {@code OS_NAME} is {@code null}.
       * </p>
       *
       * @since 3.4
       */
      public static final boolean IS_OS_MAC_OSX_LEOPARD = getOSMatches("Mac OS X", "10.5");
  
      /**
       * <p>
       * Is {@code true} if this is Mac OS X Snow Leopard.
       * </p>
       * <p>
       * The field will return {@code false} if {@code OS_NAME} is {@code null}.
       * </p>
       *
       * @since 3.4
       */
      public static final boolean IS_OS_MAC_OSX_SNOW_LEOPARD = getOSMatches("Mac OS X", "10.6");
  
      /**
       * <p>
       * Is {@code true} if this is Mac OS X Lion.
       * </p>
       * <p>
       * The field will return {@code false} if {@code OS_NAME} is {@code null}.
       * </p>
       *
       * @since 3.4
       */
      public static final boolean IS_OS_MAC_OSX_LION = getOSMatches("Mac OS X", "10.7");
  
      /**
       * <p>
       * Is {@code true} if this is Mac OS X Mountain Lion.
       * </p>
       * <p>
       * The field will return {@code false} if {@code OS_NAME} is {@code null}.
       * </p>
       *
       * @since 3.4
       */
      public static final boolean IS_OS_MAC_OSX_MOUNTAIN_LION = getOSMatches("Mac OS X", "10.8");
  
      /**
       * <p>
       * Is {@code true} if this is Mac OS X Mavericks.
       * </p>
       * <p>
       * The field will return {@code false} if {@code OS_NAME} is {@code null}.
       * </p>
       *
       * @since 3.4
       */
      public static final boolean IS_OS_MAC_OSX_MAVERICKS = getOSMatches("Mac OS X", "10.9");
  
      /**
       * <p>
       * Is {@code true} if this is Mac OS X Yosemite.
       * </p>
       * <p>
       * The field will return {@code false} if {@code OS_NAME} is {@code null}.
       * </p>
       *
       * @since 3.4
       */
      public static final boolean IS_OS_MAC_OSX_YOSEMITE = getOSMatches("Mac OS X", "10.10");
  
      /**
       * <p>
       * Is {@code true} if this is Mac OS X El Capitan.
       * </p>
       * <p>
       * The field will return {@code false} if {@code OS_NAME} is {@code null}.
       * </p>
       *
       * @since 3.5
       */
      public static final boolean IS_OS_MAC_OSX_EL_CAPITAN = getOSMatches("Mac OS X", "10.11");
  
      /**
       * <p>
       * Is {@code true} if this is FreeBSD.
       * </p>
       * <p>
       * The field will return {@code false} if {@code OS_NAME} is {@code null}.
       * </p>
       *
       * @since 3.1
       */
      public static final boolean IS_OS_FREE_BSD = getOSMatchesName("FreeBSD");
  
      /**
       * <p>
       * Is {@code true} if this is OpenBSD.
       * </p>
       * <p>
       * The field will return {@code false} if {@code OS_NAME} is {@code null}.
       * </p>
       *
       * @since 3.1
       */
      public static final boolean IS_OS_OPEN_BSD = getOSMatchesName("OpenBSD");
  
      /**
       * <p>
       * Is {@code true} if this is NetBSD.
       * </p>
       * <p>
       * The field will return {@code false} if {@code OS_NAME} is {@code null}.
       * </p>
       *
       * @since 3.1
       */
      public static final boolean IS_OS_NET_BSD = getOSMatchesName("NetBSD");
  
      /**
       * <p>
       * Is {@code true} if this is OS/2.
       * </p>
       * <p>
       * The field will return {@code false} if {@code OS_NAME} is {@code null}.
       * </p>
       *
       * @since 2.0
       */
      public static final boolean IS_OS_OS2 = getOSMatchesName("OS/2");
  
      /**
       * <p>
       * Is {@code true} if this is Solaris.
       * </p>
       * <p>
       * The field will return {@code false} if {@code OS_NAME} is {@code null}.
       * </p>
       *
       * @since 2.0
       */
      public static final boolean IS_OS_SOLARIS = getOSMatchesName("Solaris");
  
      /**
       * <p>
       * Is {@code true} if this is SunOS.
       * </p>
       * <p>
       * The field will return {@code false} if {@code OS_NAME} is {@code null}.
       * </p>
       *
       * @since 2.0
       */
      public static final boolean IS_OS_SUN_OS = getOSMatchesName("SunOS");
  
      /**
       * <p>
       * Is {@code true} if this is a UNIX like system, as in any of AIX, HP-UX, Irix, Linux, MacOSX, Solaris or SUN OS.
       * </p>
       * <p>
       * The field will return {@code false} if {@code OS_NAME} is {@code null}.
       * </p>
       *
       * @since 2.1
       */
      public static final boolean IS_OS_UNIX = IS_OS_AIX || IS_OS_HP_UX || IS_OS_IRIX || IS_OS_LINUX || IS_OS_MAC_OSX
          || IS_OS_SOLARIS || IS_OS_SUN_OS || IS_OS_FREE_BSD || IS_OS_OPEN_BSD || IS_OS_NET_BSD;
  
      /**
       * <p>
       * Is {@code true} if this is Windows.
       * </p>
       * <p>
       * The field will return {@code false} if {@code OS_NAME} is {@code null}.
       * </p>
       *
       * @since 2.0
       */
      public static final boolean IS_OS_WINDOWS = getOSMatchesName(OS_NAME_WINDOWS_PREFIX);
  
      /**
       * <p>
       * Is {@code true} if this is Windows 2000.
       * </p>
       * <p>
       * The field will return {@code false} if {@code OS_NAME} is {@code null}.
       * </p>
       *
       * @since 2.0
       */
      public static final boolean IS_OS_WINDOWS_2000 = getOSMatchesName(OS_NAME_WINDOWS_PREFIX + " 2000");
  
      /**
       * <p>
       * Is {@code true} if this is Windows 2003.
       * </p>
       * <p>
       * The field will return {@code false} if {@code OS_NAME} is {@code null}.
       * </p>
       *
       * @since 3.1
       */
      public static final boolean IS_OS_WINDOWS_2003 = getOSMatchesName(OS_NAME_WINDOWS_PREFIX + " 2003");
  
      /**
       * <p>
       * Is {@code true} if this is Windows Server 2008.
       * </p>
       * <p>
       * The field will return {@code false} if {@code OS_NAME} is {@code null}.
       * </p>
       *
       * @since 3.1
       */
      public static final boolean IS_OS_WINDOWS_2008 = getOSMatchesName(OS_NAME_WINDOWS_PREFIX + " Server 2008");
  
      /**
       * <p>
       * Is {@code true} if this is Windows Server 2012.
       * </p>
       * <p>
       * The field will return {@code false} if {@code OS_NAME} is {@code null}.
       * </p>
       *
       * @since 3.4
       */
      public static final boolean IS_OS_WINDOWS_2012 = getOSMatchesName(OS_NAME_WINDOWS_PREFIX + " Server 2012");
  
      /**
       * <p>
       * Is {@code true} if this is Windows 95.
       * </p>
       * <p>
       * The field will return {@code false} if {@code OS_NAME} is {@code null}.
       * </p>
       *
       * @since 2.0
       */
      public static final boolean IS_OS_WINDOWS_95 = getOSMatchesName(OS_NAME_WINDOWS_PREFIX + " 95");
  
      /**
       * <p>
       * Is {@code true} if this is Windows 98.
       * </p>
       * <p>
       * The field will return {@code false} if {@code OS_NAME} is {@code null}.
       * </p>
       *
       * @since 2.0
       */
      public static final boolean IS_OS_WINDOWS_98 = getOSMatchesName(OS_NAME_WINDOWS_PREFIX + " 98");
  
      /**
       * <p>
       * Is {@code true} if this is Windows ME.
       * </p>
       * <p>
       * The field will return {@code false} if {@code OS_NAME} is {@code null}.
       * </p>
       *
       * @since 2.0
       */
      public static final boolean IS_OS_WINDOWS_ME = getOSMatchesName(OS_NAME_WINDOWS_PREFIX + " Me");
  
      /**
       * <p>
       * Is {@code true} if this is Windows NT.
       * </p>
       * <p>
       * The field will return {@code false} if {@code OS_NAME} is {@code null}.
       * </p>
       *
       * @since 2.0
       */
      public static final boolean IS_OS_WINDOWS_NT = getOSMatchesName(OS_NAME_WINDOWS_PREFIX + " NT");
  
      /**
       * <p>
       * Is {@code true} if this is Windows XP.
       * </p>
       * <p>
       * The field will return {@code false} if {@code OS_NAME} is {@code null}.
       * </p>
       *
       * @since 2.0
       */
      public static final boolean IS_OS_WINDOWS_XP = getOSMatchesName(OS_NAME_WINDOWS_PREFIX + " XP");
  
      // -----------------------------------------------------------------------
      /**
       * <p>
       * Is {@code true} if this is Windows Vista.
       * </p>
       * <p>
       * The field will return {@code false} if {@code OS_NAME} is {@code null}.
       * </p>
       *
       * @since 2.4
       */
      public static final boolean IS_OS_WINDOWS_VISTA = getOSMatchesName(OS_NAME_WINDOWS_PREFIX + " Vista");
  
      /**
       * <p>
       * Is {@code true} if this is Windows 7.
       * </p>
       * <p>
       * The field will return {@code false} if {@code OS_NAME} is {@code null}.
       * </p>
       *
       * @since 3.0
       */
      public static final boolean IS_OS_WINDOWS_7 = getOSMatchesName(OS_NAME_WINDOWS_PREFIX + " 7");
  
      /**
       * <p>
       * Is {@code true} if this is Windows 8.
       * </p>
       * <p>
       * The field will return {@code false} if {@code OS_NAME} is {@code null}.
       * </p>
       *
       * @since 3.2
       */
      public static final boolean IS_OS_WINDOWS_8 = getOSMatchesName(OS_NAME_WINDOWS_PREFIX + " 8");
  
      /**
       * <p>
       * Is {@code true} if this is Windows 10.
       * </p>
       * <p>
       * The field will return {@code false} if {@code OS_NAME} is {@code null}.
       * </p>
       *
       * @since 3.5
       */
      public static final boolean IS_OS_WINDOWS_10 = getOSMatchesName(OS_NAME_WINDOWS_PREFIX + " 10");
  
      /**
       * <p>
       * Is {@code true} if this is z/OS.
       * </p>
       * <p>
       * The field will return {@code false} if {@code OS_NAME} is {@code null}.
       * </p>
       *
       * @since 3.5
       */
      // Values on a z/OS system I tested (Gary Gregory - 2016-03-12)
      // os.arch = s390x
      // os.encoding = ISO8859_1
      // os.name = z/OS
      // os.version = 02.02.00
      public static final boolean IS_OS_ZOS = getOSMatchesName("z/OS");
  
      /**
       * <p>
       * Gets the Java home directory as a {@code File}.
       * </p>
       *
       * @return a directory
       * @throws SecurityException if a security manager exists and its {@code checkPropertyAccess} method doesn't allow
       * access to the specified system property.
       * @see System#getProperty(String)
       * @since 2.1
       */
      public static File getJavaHome() {
          return new File(System.getProperty(JAVA_HOME_KEY));
      }
  
      /**
       * <p>
       * Gets the Java IO temporary directory as a {@code File}.
       * </p>
       *
       * @return a directory
       * @throws SecurityException if a security manager exists and its {@code checkPropertyAccess} method doesn't allow
       * access to the specified system property.
       * @see System#getProperty(String)
       * @since 2.1
       */
      public static File getJavaIoTmpDir() {
          return new File(System.getProperty(JAVA_IO_TMPDIR_KEY));
      }
  
      /**
       * <p>
       * Decides if the Java version matches.
       * </p>
       *
       * @param versionPrefix the prefix for the java version
       * @return true if matches, or false if not or can't determine
       */
      private static boolean getJavaVersionMatches(final String versionPrefix) {
          return isJavaVersionMatch(JAVA_SPECIFICATION_VERSION, versionPrefix);
      }
  
      /**
       * Decides if the operating system matches.
       *
       * @param osNamePrefix the prefix for the os name
       * @param osVersionPrefix the prefix for the version
       * @return true if matches, or false if not or can't determine
       */
      private static boolean getOSMatches(final String osNamePrefix, final String osVersionPrefix) {
          return isOSMatch(OS_NAME, OS_VERSION, osNamePrefix, osVersionPrefix);
      }
  
      /**
       * Decides if the operating system matches.
       *
       * @param osNamePrefix the prefix for the os name
       * @return true if matches, or false if not or can't determine
       */
      private static boolean getOSMatchesName(final String osNamePrefix) {
          return isOSNameMatch(OS_NAME, osNamePrefix);
      }
  
      // -----------------------------------------------------------------------
      /**
       * <p>
       * Gets a System property, defaulting to {@code null} if the property cannot be read.
       * </p>
       * <p>
       * If a {@code SecurityException} is caught, the return value is {@code null} and a message is written to
       * {@code System.err}.
       * </p>
       *
       * @param property the system property name
       * @return the system property value or {@code null} if a security problem occurs
       */
      private static String getSystemProperty(final String property) {
          try {
              return System.getProperty(property);
          } catch (final SecurityException ex) {
              // we are not allowed to look at this property
              System.err.println("Caught a SecurityException reading the system property '" + property
                  + "'; the SystemUtils property value will default to null.");
              return null;
          }
      }
  
      /**
       * <p>
       * Gets the user directory as a {@code File}.
       * </p>
       *
       * @return a directory
       * @throws SecurityException if a security manager exists and its {@code checkPropertyAccess} method doesn't allow
       * access to the specified system property.
       * @see System#getProperty(String)
       * @since 2.1
       */
      public static File getUserDir() {
          return new File(System.getProperty(USER_DIR_KEY));
      }
  
      /**
       * <p>
       * Gets the user home directory as a {@code File}.
       * </p>
       *
       * @return a directory
       * @throws SecurityException if a security manager exists and its {@code checkPropertyAccess} method doesn't allow
       * access to the specified system property.
       * @see System#getProperty(String)
       * @since 2.1
       */
      public static File getUserHome() {
          return new File(System.getProperty(USER_HOME_KEY));
      }
  
      /**
       * Returns whether the {@link #JAVA_AWT_HEADLESS} value is {@code true}.
       *
       * @return {@code true} if {@code JAVA_AWT_HEADLESS} is {@code "true"}, {@code false} otherwise.
       * @see #JAVA_AWT_HEADLESS
       * @since 2.1
       * @since Java 1.4
       */
      public static boolean isJavaAwtHeadless() {
          return JAVA_AWT_HEADLESS != null ? JAVA_AWT_HEADLESS.equals(Boolean.TRUE.toString()) : false;
      }
  
      /**
       * <p>
       * Is the Java version at least the requested version.
       * </p>
       * <p>
       * Example input:
       * </p>
       * <ul>
       * <li>{@code 1.2f} to test for Java 1.2</li>
       * <li>{@code 1.31f} to test for Java 1.3.1</li>
       * </ul>
       *
       * @param requiredVersion the required version, for example 1.31f
       * @return {@code true} if the actual version is equal or greater than the required version
       */
      public static boolean isJavaVersionAtLeast(final JavaVersion requiredVersion) {
          return JAVA_SPECIFICATION_VERSION_AS_ENUM.atLeast(requiredVersion);
      }
  
      /**
       * <p>
       * Decides if the Java version matches.
       * </p>
       * <p>
       * This method is package private instead of private to support unit test invocation.
       * </p>
       *
       * @param version the actual Java version
       * @param versionPrefix the prefix for the expected Java version
       * @return true if matches, or false if not or can't determine
       */
      static boolean isJavaVersionMatch(final String version, final String versionPrefix) {
          if (version == null) {
              return false;
          }
          return version.startsWith(versionPrefix);
      }
  
      /**
       * Decides if the operating system matches.
       * <p>
       * This method is package private instead of private to support unit test invocation.
       * </p>
       *
       * @param osName the actual OS name
       * @param osVersion the actual OS version
       * @param osNamePrefix the prefix for the expected OS name
       * @param osVersionPrefix the prefix for the expected OS version
       * @return true if matches, or false if not or can't determine
       */
      static boolean isOSMatch(final String osName, final String osVersion, final String osNamePrefix, final String osVersionPrefix) {
          if (osName == null || osVersion == null) {
              return false;
          }
          return isOSNameMatch(osName, osNamePrefix) && isOSVersionMatch(osVersion, osVersionPrefix);
      }
  
      /**
       * Decides if the operating system matches.
       * <p>
       * This method is package private instead of private to support unit test invocation.
       * </p>
       *
       * @param osName the actual OS name
       * @param osNamePrefix the prefix for the expected OS name
       * @return true if matches, or false if not or can't determine
       */
      static boolean isOSNameMatch(final String osName, final String osNamePrefix) {
          if (osName == null) {
              return false;
          }
          return osName.startsWith(osNamePrefix);
      }
  
      /**
       * Decides if the operating system version matches.
       * <p>
       * This method is package private instead of private to support unit test invocation.
       * </p>
       *
       * @param osVersion the actual OS version
       * @param osVersionPrefix the prefix for the expected OS version
       * @return true if matches, or false if not or can't determine
       */
      static boolean isOSVersionMatch(final String osVersion, final String osVersionPrefix) {
          if (osVersion == null || osVersion.trim().isEmpty()) {
              return false;
          }
          // Compare parts of the version string instead of using String.startsWith(String) because otherwise
          // osVersionPrefix 10.1 would also match osVersion 10.10
          String[] versionPrefixParts = osVersionPrefix.split("\\.");
          String[] versionParts = osVersion.split("\\.");
          for (int i = 0; i < Math.min(versionPrefixParts.length, versionParts.length); i++) {
              if (!versionPrefixParts[i].equals(versionParts[i])) {
                  return false;
              }
          }
          return true;
      }
  
      // -----------------------------------------------------------------------
      /**
       * <p>
       * SystemUtils instances should NOT be constructed in standard programming. Instead, the class should be used as
       * {@code SystemUtils.FILE_SEPARATOR}.
       * </p>
       * <p>
       * This constructor is public to permit tools that require a JavaBean instance to operate.
       * </p>
       */
      public SystemUtils() {
          super();
      }
  
  }