1 /*
2 * Copyright (C) 2012 The Guava Authors
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
5 * in compliance with the License. You may obtain a copy of the License at
6 *
7 * http://www.apache.org/licenses/LICENSE-2.0
8 *
9 * Unless required by applicable law or agreed to in writing, software distributed under the License
10 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
11 * or implied. See the License for the specific language governing permissions and limitations under
12 * the License.
13 */
14
15 package com.google.common.base;
16
17 import com.google.common.annotations.GwtIncompatible;
18 import javax.annotation.CheckForNull;
19
20 /**
21 * Represents a {@linkplain System#getProperties() standard system property}.
22 *
23 * @author Kurt Alfred Kluever
24 * @since 15.0
25 */
26 @GwtIncompatible // java.lang.System#getProperty
27 @ElementTypesAreNonnullByDefault
28 public enum StandardSystemProperty {
29
30 /** Java Runtime Environment version. */
31 JAVA_VERSION("java.version"),
32
33 /** Java Runtime Environment vendor. */
34 JAVA_VENDOR("java.vendor"),
35
36 /** Java vendor URL. */
37 JAVA_VENDOR_URL("java.vendor.url"),
38
39 /** Java installation directory. */
40 JAVA_HOME("java.home"),
41
42 /** Java Virtual Machine specification version. */
43 JAVA_VM_SPECIFICATION_VERSION("java.vm.specification.version"),
44
45 /** Java Virtual Machine specification vendor. */
46 JAVA_VM_SPECIFICATION_VENDOR("java.vm.specification.vendor"),
47
48 /** Java Virtual Machine specification name. */
49 JAVA_VM_SPECIFICATION_NAME("java.vm.specification.name"),
50
51 /** Java Virtual Machine implementation version. */
52 JAVA_VM_VERSION("java.vm.version"),
53
54 /** Java Virtual Machine implementation vendor. */
55 JAVA_VM_VENDOR("java.vm.vendor"),
56
57 /** Java Virtual Machine implementation name. */
58 JAVA_VM_NAME("java.vm.name"),
59
60 /** Java Runtime Environment specification version. */
61 JAVA_SPECIFICATION_VERSION("java.specification.version"),
62
63 /** Java Runtime Environment specification vendor. */
64 JAVA_SPECIFICATION_VENDOR("java.specification.vendor"),
65
66 /** Java Runtime Environment specification name. */
67 JAVA_SPECIFICATION_NAME("java.specification.name"),
68
69 /** Java class format version number. */
70 JAVA_CLASS_VERSION("java.class.version"),
71
72 /** Java class path. */
73 JAVA_CLASS_PATH("java.class.path"),
74
75 /** List of paths to search when loading libraries. */
76 JAVA_LIBRARY_PATH("java.library.path"),
77
78 /** Default temp file path. */
79 JAVA_IO_TMPDIR("java.io.tmpdir"),
80
81 /** Name of JIT compiler to use. */
82 JAVA_COMPILER("java.compiler"),
83
84 /**
85 * Path of extension directory or directories.
86 *
87 * @deprecated This property was <a
88 * href="https://openjdk.java.net/jeps/220#Removed:-The-extension-mechanism">deprecated</a> in
89 * Java 8 and removed in Java 9. We do not plan to remove this API from Guava, but if you are
90 * using it, it is probably not doing what you want.
91 */
92 @Deprecated
93 JAVA_EXT_DIRS("java.ext.dirs"),
94
95 /** Operating system name. */
96 OS_NAME("os.name"),
97
98 /** Operating system architecture. */
99 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 }