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 javax.annotation.CheckForNull;
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
027@ElementTypesAreNonnullByDefault
028public enum StandardSystemProperty {
029
030  /** Java Runtime Environment version. */
031  JAVA_VERSION("java.version"),
032
033  /** Java Runtime Environment vendor. */
034  JAVA_VENDOR("java.vendor"),
035
036  /** Java vendor URL. */
037  JAVA_VENDOR_URL("java.vendor.url"),
038
039  /** Java installation directory. */
040  JAVA_HOME("java.home"),
041
042  /** Java Virtual Machine specification version. */
043  JAVA_VM_SPECIFICATION_VERSION("java.vm.specification.version"),
044
045  /** Java Virtual Machine specification vendor. */
046  JAVA_VM_SPECIFICATION_VENDOR("java.vm.specification.vendor"),
047
048  /** Java Virtual Machine specification name. */
049  JAVA_VM_SPECIFICATION_NAME("java.vm.specification.name"),
050
051  /** Java Virtual Machine implementation version. */
052  JAVA_VM_VERSION("java.vm.version"),
053
054  /** Java Virtual Machine implementation vendor. */
055  JAVA_VM_VENDOR("java.vm.vendor"),
056
057  /** Java Virtual Machine implementation name. */
058  JAVA_VM_NAME("java.vm.name"),
059
060  /** Java Runtime Environment specification version. */
061  JAVA_SPECIFICATION_VERSION("java.specification.version"),
062
063  /** Java Runtime Environment specification vendor. */
064  JAVA_SPECIFICATION_VENDOR("java.specification.vendor"),
065
066  /** Java Runtime Environment specification name. */
067  JAVA_SPECIFICATION_NAME("java.specification.name"),
068
069  /** Java class format version number. */
070  JAVA_CLASS_VERSION("java.class.version"),
071
072  /** Java class path. */
073  JAVA_CLASS_PATH("java.class.path"),
074
075  /** List of paths to search when loading libraries. */
076  JAVA_LIBRARY_PATH("java.library.path"),
077
078  /** Default temp file path. */
079  JAVA_IO_TMPDIR("java.io.tmpdir"),
080
081  /** Name of JIT compiler to use. */
082  JAVA_COMPILER("java.compiler"),
083
084  /**
085   * Path of extension directory or directories.
086   *
087   * @deprecated This property was <a
088   *     href="https://openjdk.java.net/jeps/220#Removed:-The-extension-mechanism">deprecated</a> in
089   *     Java 8 and removed in Java 9. We do not plan to remove this API from Guava, but if you are
090   *     using it, it is probably not doing what you want.
091   */
092  @Deprecated
093  JAVA_EXT_DIRS("java.ext.dirs"),
094
095  /** Operating system name. */
096  OS_NAME("os.name"),
097
098  /** Operating system architecture. */
099  OS_ARCH("os.arch"),
100
101  /** Operating system version. */
102  OS_VERSION("os.version"),
103
104  /** File separator ("/" on UNIX). */
105  FILE_SEPARATOR("file.separator"),
106
107  /** Path separator (":" on UNIX). */
108  PATH_SEPARATOR("path.separator"),
109
110  /** Line separator ("\n" on UNIX). */
111  LINE_SEPARATOR("line.separator"),
112
113  /** User's account name. */
114  USER_NAME("user.name"),
115
116  /** User's home directory. */
117  USER_HOME("user.home"),
118
119  /** User's current working directory. */
120  USER_DIR("user.dir");
121
122  private final String key;
123
124  StandardSystemProperty(String key) {
125    this.key = key;
126  }
127
128  /** Returns the key used to lookup this system property. */
129  public String key() {
130    return key;
131  }
132
133  /**
134   * Returns the current value for this system property by delegating to {@link
135   * System#getProperty(String)}.
136   *
137   * <p>The value returned by this method is non-null except in rare circumstances:
138   *
139   * <ul>
140   *   <li>{@link #JAVA_EXT_DIRS} was deprecated in Java 8 and removed in Java 9. We have not
141   *       confirmed whether it is available under older versions.
142   *   <li>{@link #JAVA_COMPILER}, while still listed as required as of Java 15, is typically not
143   *       available even under older version.
144   *   <li>Any property may be cleared through APIs like {@link System#clearProperty}.
145   *   <li>Unusual environments like GWT may have their own special handling of system properties.
146   * </ul>
147   *
148   * <p>Note that {@code StandardSystemProperty} does not provide constants for more recently added
149   * properties, including:
150   *
151   * <ul>
152   *   <li>{@code java.vendor.version} (added in Java 11, listed as optional as of Java 13)
153   *   <li>{@code jdk.module.*} (added in Java 9, optional)
154   * </ul>
155   */
156  @CheckForNull
157  public String value() {
158    return System.getProperty(key);
159  }
160
161  /** Returns a string representation of this system property. */
162  @Override
163  public String toString() {
164    return key() + "=" + value();
165  }
166}