001/*
002 * Copyright (C) 2012 The Guava Authors
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
005 * in compliance with the License. You may obtain a copy of the License at
006 *
007 * http://www.apache.org/licenses/LICENSE-2.0
008 *
009 * Unless required by applicable law or agreed to in writing, software distributed under the License
010 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
011 * or implied. See the License for the specific language governing permissions and limitations under
012 * the License.
013 */
014
015package com.google.common.base;
016
017import com.google.common.annotations.GwtIncompatible;
018import org.checkerframework.checker.nullness.qual.Nullable;
019
020/**
021 * Represents a {@linkplain System#getProperties() standard system property}.
022 *
023 * @author Kurt Alfred Kluever
024 * @since 15.0
025 */
026@GwtIncompatible // java.lang.System#getProperty
027public enum StandardSystemProperty {
028
029  /** Java Runtime Environment version. */
030  JAVA_VERSION("java.version"),
031
032  /** Java Runtime Environment vendor. */
033  JAVA_VENDOR("java.vendor"),
034
035  /** Java vendor URL. */
036  JAVA_VENDOR_URL("java.vendor.url"),
037
038  /** Java installation directory. */
039  JAVA_HOME("java.home"),
040
041  /** Java Virtual Machine specification version. */
042  JAVA_VM_SPECIFICATION_VERSION("java.vm.specification.version"),
043
044  /** Java Virtual Machine specification vendor. */
045  JAVA_VM_SPECIFICATION_VENDOR("java.vm.specification.vendor"),
046
047  /** Java Virtual Machine specification name. */
048  JAVA_VM_SPECIFICATION_NAME("java.vm.specification.name"),
049
050  /** Java Virtual Machine implementation version. */
051  JAVA_VM_VERSION("java.vm.version"),
052
053  /** Java Virtual Machine implementation vendor. */
054  JAVA_VM_VENDOR("java.vm.vendor"),
055
056  /** Java Virtual Machine implementation name. */
057  JAVA_VM_NAME("java.vm.name"),
058
059  /** Java Runtime Environment specification version. */
060  JAVA_SPECIFICATION_VERSION("java.specification.version"),
061
062  /** Java Runtime Environment specification vendor. */
063  JAVA_SPECIFICATION_VENDOR("java.specification.vendor"),
064
065  /** Java Runtime Environment specification name. */
066  JAVA_SPECIFICATION_NAME("java.specification.name"),
067
068  /** Java class format version number. */
069  JAVA_CLASS_VERSION("java.class.version"),
070
071  /** Java class path. */
072  JAVA_CLASS_PATH("java.class.path"),
073
074  /** List of paths to search when loading libraries. */
075  JAVA_LIBRARY_PATH("java.library.path"),
076
077  /** Default temp file path. */
078  JAVA_IO_TMPDIR("java.io.tmpdir"),
079
080  /** Name of JIT compiler to use. */
081  JAVA_COMPILER("java.compiler"),
082
083  /**
084   * Path of extension directory or directories.
085   *
086   * @deprecated This property was <a
087   *     href="https://openjdk.java.net/jeps/220#Removed:-The-extension-mechanism">deprecated</a> in
088   *     Java 8 and removed in Java 9. We do not plan to remove this API from Guava, but if you are
089   *     using it, it is probably not doing what you want.
090   */
091  @Deprecated
092  JAVA_EXT_DIRS("java.ext.dirs"),
093
094  /** Operating system name. */
095  OS_NAME("os.name"),
096
097  /** Operating system architecture. */
098  OS_ARCH("os.arch"),
099
100  /** Operating system version. */
101  OS_VERSION("os.version"),
102
103  /** File separator ("/" on UNIX). */
104  FILE_SEPARATOR("file.separator"),
105
106  /** Path separator (":" on UNIX). */
107  PATH_SEPARATOR("path.separator"),
108
109  /** Line separator ("\n" on UNIX). */
110  LINE_SEPARATOR("line.separator"),
111
112  /** User's account name. */
113  USER_NAME("user.name"),
114
115  /** User's home directory. */
116  USER_HOME("user.home"),
117
118  /** User's current working directory. */
119  USER_DIR("user.dir");
120
121  private final String key;
122
123  StandardSystemProperty(String key) {
124    this.key = key;
125  }
126
127  /** Returns the key used to lookup this system property. */
128  public String key() {
129    return key;
130  }
131
132  /**
133   * Returns the current value for this system property by delegating to {@link
134   * System#getProperty(String)}.
135   *
136   * <p>The value returned by this method is non-null except in rare circumstances:
137   *
138   * <ul>
139   *   <li>{@link #JAVA_EXT_DIRS} was deprecated in Java 8 and removed in Java 9. We have not
140   *       confirmed whether it is available under older versions.
141   *   <li>{@link #JAVA_COMPILER}, while still listed as required as of Java 15, is typically not
142   *       available even under older version.
143   *   <li>Any property may be cleared through APIs like {@link System#clearProperty}.
144   *   <li>Unusual environments like GWT may have their own special handling of system properties.
145   * </ul>
146   *
147   * <p>Note that {@code StandardSystemProperty} does not provide constants for more recently added
148   * properties, including:
149   *
150   * <ul>
151   *   <li>{@code java.vendor.version} (added in Java 11, listed as optional as of Java 13)
152   *   <li>{@code jdk.module.*} (added in Java 9, optional)
153   * </ul>
154   */
155  public @Nullable String value() {
156    return System.getProperty(key);
157  }
158
159  /** Returns a string representation of this system property. */
160  @Override
161  public String toString() {
162    return key() + "=" + value();
163  }
164}