java.lang.System Maven / Gradle / Ivy
/*
* 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.
*/
/*
* Copyright (C) 2008 The Android Open Source Project
*
* Licensed 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.
*/
/*
* Copyright (C) 2012 Trillian Mobile AB
*
* Licensed 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 java.lang;
import dalvik.system.VMRuntime;
import dalvik.system.VMStack;
import java.io.BufferedInputStream;
import java.io.Console;
import java.io.FileDescriptor;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintStream;
import java.nio.channels.Channel;
import java.nio.channels.spi.SelectorProvider;
import java.util.AbstractMap;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;
import java.util.Set;
import libcore.icu.ICU;
import libcore.io.ErrnoException;
import libcore.io.Libcore;
import libcore.io.StructPasswd;
import libcore.io.StructUtsname;
import libcore.util.ZoneInfoDB;
import org.robovm.rt.VM;
/**
* Provides access to system-related information and resources including
* standard input and output. Enables clients to dynamically load native
* libraries. All methods of this class are accessed in a static way and the
* class itself can not be instantiated.
*
* @see Runtime
*/
public final class System {
/**
* Default input stream.
*/
public static final InputStream in;
/**
* Default output stream.
*/
public static final PrintStream out;
/**
* Default error output stream.
*/
public static final PrintStream err;
private static final String lineSeparator;
private static Properties systemProperties;
static {
err = new PrintStream(new FileOutputStream(FileDescriptor.err));
out = new PrintStream(new FileOutputStream(FileDescriptor.out));
in = new BufferedInputStream(new FileInputStream(FileDescriptor.in));
lineSeparator = System.getProperty("line.separator");
}
/**
* Sets the standard input stream to the given user defined input stream.
*
* @param newIn
* the user defined input stream to set as the standard input
* stream.
*/
public static void setIn(InputStream newIn) {
setFieldImpl("in", "Ljava/io/InputStream;", newIn);
}
/**
* Sets the standard output stream to the given user defined output stream.
*
* @param newOut
* the user defined output stream to set as the standard output
* stream.
*/
public static void setOut(PrintStream newOut) {
setFieldImpl("out", "Ljava/io/PrintStream;", newOut);
}
/**
* Sets the standard error output stream to the given user defined output
* stream.
*
* @param newErr
* the user defined output stream to set as the standard error
* output stream.
*/
public static void setErr(PrintStream newErr) {
setFieldImpl("err", "Ljava/io/PrintStream;", newErr);
}
/**
* Prevents this class from being instantiated.
*/
private System() {
}
/**
* Copies {@code length} elements from the array {@code src},
* starting at offset {@code srcPos}, into the array {@code dst},
* starting at offset {@code dstPos}.
*
* The source and destination arrays can be the same array,
* in which case copying is performed as if the source elements
* are first copied into a temporary array and then into the
* destination array.
*
* @param src
* the source array to copy the content.
* @param srcPos
* the starting index of the content in {@code src}.
* @param dst
* the destination array to copy the data into.
* @param dstPos
* the starting index for the copied content in {@code dst}.
* @param length
* the number of elements to be copied.
*/
public static void arraycopy(Object src, int srcPos, Object dst, int dstPos,
int length) {
// RoboVM note: This is native in Android. We're using code from Apache Harmony instead.
if (src == null) {
throw new NullPointerException("src == null");
}
if (dst == null) {
throw new NullPointerException("dst == null");
}
Class type1 = src.getClass();
Class type2 = dst.getClass();
if (!type1.isArray()) {
throw new ArrayStoreException("source of type " + type1.getName() + " is not an array");
}
if (!type2.isArray()) {
throw new ArrayStoreException("destination of type " + type2.getName() + " is not an array");
}
Class componentType1 = type1.getComponentType();
Class componentType2 = type2.getComponentType();
if (!componentType1.isPrimitive()) {
if (componentType2.isPrimitive()) {
throw new ArrayStoreException(type1.getCanonicalName() + " and " + type2.getCanonicalName()
+ " are incompatible array types");
}
arraycopy((Object[]) src, srcPos, (Object[]) dst, dstPos, length);
} else {
if (componentType2 != componentType1) {
throw new ArrayStoreException(type1.getCanonicalName() + " and " + type2.getCanonicalName()
+ " are incompatible array types");
}
if (componentType1 == int.class) {
arraycopy((int[]) src, srcPos, (int[]) dst, dstPos, length);
} else if (componentType1 == byte.class) {
arraycopy((byte[]) src, srcPos, (byte[]) dst, dstPos, length);
} else if (componentType1 == long.class) {
arraycopy((long[]) src, srcPos, (long[]) dst, dstPos, length);
} else if (componentType1 == short.class) {
arraycopy((short[]) src, srcPos, (short[]) dst, dstPos, length);
} else if (componentType1 == char.class) {
arraycopy((char[]) src, srcPos, (char[]) dst, dstPos, length);
} else if (componentType1 == boolean.class) {
arraycopy((boolean[]) src, srcPos, (boolean[]) dst, dstPos, length);
} else if (componentType1 == double.class) {
arraycopy((double[]) src, srcPos, (double[]) dst, dstPos, length);
} else if (componentType1 == float.class) {
arraycopy((float[]) src, srcPos, (float[]) dst, dstPos, length);
}
}
}
private static void arraycopyCheckBounds(int srcLength, int srcPos, int dstLength, int dstPos, int length) {
if (srcPos < 0 || dstPos < 0 || length < 0 ||
srcPos > srcLength - length ||
dstPos > dstLength - length) {
throw new ArrayIndexOutOfBoundsException("src.length=" + srcLength + " srcPos=" + srcPos
+ " dst.length=" + dstLength + " dstPos=" + dstPos + " length=" + length);
}
}
private static void arraycopyFast(Object src, int srcPos, Object dst, int dstPos, int length, int logElemSize) {
if (length > 0) {
long srcAddr = VM.getArrayValuesAddress(src) + (srcPos << logElemSize);
long dstAddr = VM.getArrayValuesAddress(dst) + (dstPos << logElemSize);
if (logElemSize == 0) {
VM.memmove8(dstAddr, srcAddr, length);
} else if (logElemSize == 1) {
VM.memmove16(dstAddr, srcAddr, length);
} else if (logElemSize == 2) {
VM.memmove32(dstAddr, srcAddr, length);
} else if (logElemSize == 3) {
VM.memmove64(dstAddr, srcAddr, length);
} else {
throw new AssertionError();
}
}
}
private static void arraycopy(Object[] src, int srcPos, Object[] dst, int dstPos, int length) {
arraycopyCheckBounds(src.length, srcPos, dst.length, dstPos, length);
if (length > 0) {
// TODO: Use arraycopyFast() if src.class and dst.class have same dimensionality and (src instanceof dst)
int i = 0;
try {
// Check if this is a forward or backwards arraycopy
if (src != dst || srcPos > dstPos || srcPos + length <= dstPos) {
for (i = 0; i < length; ++i) {
dst[dstPos + i] = src[srcPos + i];
}
} else {
for (i = length - 1; i >= 0; --i) {
dst[dstPos + i] = src[srcPos + i];
}
}
} catch (ArrayStoreException e) {
// Throw a new one with a more descriptive message.
Class srcElemClass = src[i + srcPos].getClass();
String srcElemTypeName = srcElemClass.isArray()
? srcElemClass.getCanonicalName() : srcElemClass.getName();
throw new ArrayStoreException(String.format(
"source[%d] of type %s cannot be stored in destination array of type %s",
i + srcPos, srcElemTypeName, dst.getClass().getCanonicalName()));
}
}
}
private static void arraycopy(int[] src, int srcPos, int[] dst, int dstPos, int length) {
arraycopyCheckBounds(src.length, srcPos, dst.length, dstPos, length);
arraycopyFast(src, srcPos, dst, dstPos, length, 2);
}
private static void arraycopy(byte[] src, int srcPos, byte[] dst, int dstPos, int length) {
arraycopyCheckBounds(src.length, srcPos, dst.length, dstPos, length);
arraycopyFast(src, srcPos, dst, dstPos, length, 0);
}
private static void arraycopy(short[] src, int srcPos, short[] dst, int dstPos, int length) {
arraycopyCheckBounds(src.length, srcPos, dst.length, dstPos, length);
arraycopyFast(src, srcPos, dst, dstPos, length, 1);
}
private static void arraycopy(long[] src, int srcPos, long[] dst, int dstPos, int length) {
arraycopyCheckBounds(src.length, srcPos, dst.length, dstPos, length);
arraycopyFast(src, srcPos, dst, dstPos, length, 3);
}
private static void arraycopy(char[] src, int srcPos, char[] dst, int dstPos, int length) {
arraycopyCheckBounds(src.length, srcPos, dst.length, dstPos, length);
arraycopyFast(src, srcPos, dst, dstPos, length, 1);
}
private static void arraycopy(boolean[] src, int srcPos, boolean[] dst, int dstPos, int length) {
arraycopyCheckBounds(src.length, srcPos, dst.length, dstPos, length);
arraycopyFast(src, srcPos, dst, dstPos, length, 0);
}
private static void arraycopy(double[] src, int srcPos, double[] dst, int dstPos, int length) {
arraycopyCheckBounds(src.length, srcPos, dst.length, dstPos, length);
arraycopyFast(src, srcPos, dst, dstPos, length, 3);
}
private static void arraycopy(float[] src, int srcPos, float[] dst, int dstPos, int length) {
arraycopyCheckBounds(src.length, srcPos, dst.length, dstPos, length);
arraycopyFast(src, srcPos, dst, dstPos, length, 2);
}
/**
* Returns the current time in milliseconds since January 1, 1970 00:00:00.0 UTC.
*
*
This method always returns UTC times, regardless of the system's time zone.
* This is often called "Unix time" or "epoch time".
* Use a {@link java.text.DateFormat} instance to format this time for display to a human.
*
*
This method shouldn't be used for measuring timeouts or
* other elapsed time measurements, as changing the system time can affect
* the results. Use {@link #nanoTime} for that.
*/
public static native long currentTimeMillis();
/**
* Returns the current timestamp of the most precise timer available on the
* local system, in nanoseconds. Equivalent to Linux's {@code CLOCK_MONOTONIC}.
*
*
This timestamp should only be used to measure a duration by comparing it
* against another timestamp on the same device.
* Values returned by this method do not have a defined correspondence to
* wall clock times; the zero value is typically whenever the device last booted.
* Use {@link #currentTimeMillis} if you want to know what time it is.
*/
public static native long nanoTime();
/**
* Causes the VM to stop running and the program to exit with the given exit status.
* If {@link #runFinalizersOnExit(boolean)} has been previously invoked with a
* {@code true} argument, then all objects will be properly
* garbage-collected and finalized first.
*/
public static void exit(int code) {
Runtime.getRuntime().exit(code);
}
/**
* Indicates to the VM that it would be a good time to run the
* garbage collector. Note that this is a hint only. There is no guarantee
* that the garbage collector will actually be run.
*/
public static void gc() {
Runtime.getRuntime().gc();
}
/**
* Returns the value of the environment variable with the given name, or null if no such
* variable exists.
*/
public static String getenv(String name) {
if (name == null) {
throw new NullPointerException("name == null");
}
return Libcore.os.getenv(name);
}
/**
* Returns an unmodifiable map of all environment variables to their values.
*/
public static Map getenv() {
Map map = new HashMap();
for (String entry : Libcore.os.environ()) {
int index = entry.indexOf('=');
if (index != -1) {
map.put(entry.substring(0, index), entry.substring(index + 1));
}
}
return new SystemEnvironment(map);
}
/**
* Returns the inherited channel from the creator of the current virtual
* machine.
*
* @return the inherited {@link Channel} or {@code null} if none exists.
* @throws IOException
* if an I/O error occurred.
* @see SelectorProvider
* @see SelectorProvider#inheritedChannel()
*/
public static Channel inheritedChannel() throws IOException {
return SelectorProvider.provider().inheritedChannel();
}
/**
* Returns the system properties. Note that this is not a copy, so that
* changes made to the returned Properties object will be reflected in
* subsequent calls to getProperty and getProperties.
*
* @return the system properties.
*/
public static Properties getProperties() {
if (systemProperties == null) {
initSystemProperties();
}
return systemProperties;
}
private static void initSystemProperties() {
VMRuntime runtime = VMRuntime.getRuntime();
Properties p = new Properties();
String projectUrl = "http://www.robovm.org/";
String projectName = "RoboVM";
p.put("java.boot.class.path", runtime.bootClassPath());
p.put("java.class.path", runtime.classPath());
// None of these four are meaningful on Android, but these keys are guaranteed
// to be present for System.getProperty. For java.class.version, we use the maximum
// class file version that dx currently supports.
p.put("java.class.version", "50.0");
p.put("java.compiler", "");
p.put("java.ext.dirs", "");
p.put("java.version", "0");
// RoboVM note: Android uses getenv("JAVA_HOME") here with "/system" as fallback.
p.put("java.home", VM.basePath());
// RoboVM note: Use value of $TMPDIR if set. Otherwise use /tmp as Android does.
String tmpdir = getenv("TMPDIR");
p.put("java.io.tmpdir", tmpdir != null ? tmpdir : "/tmp");
String ldLibraryPath = getenv("LD_LIBRARY_PATH");
if (ldLibraryPath != null) {
p.put("java.library.path", ldLibraryPath);
}
p.put("java.specification.name", "RoboVM Core Library");
p.put("java.specification.vendor", projectName);
p.put("java.specification.version", "0.9");
p.put("java.vendor", projectName);
p.put("java.vendor.url", projectUrl);
p.put("java.vm.name", "RoboVM");
p.put("java.vm.specification.name", "RoboVM Virtual Machine Specification");
p.put("java.vm.specification.vendor", projectName);
p.put("java.vm.specification.version", "0.9");
p.put("java.vm.vendor", projectName);
p.put("java.vm.version", runtime.vmVersion());
p.put("file.separator", "/");
p.put("line.separator", "\n");
p.put("path.separator", ":");
p.put("java.runtime.name", "RoboVM Runtime");
p.put("java.runtime.version", "0.9");
p.put("java.vm.vendor.url", projectUrl);
p.put("file.encoding", "UTF-8");
p.put("user.language", "en");
p.put("user.region", "US");
try {
StructPasswd passwd = Libcore.os.getpwuid(Libcore.os.getuid());
p.put("user.home", passwd.pw_dir);
p.put("user.name", passwd.pw_name);
} catch (ErrnoException exception) {
// RoboVM note: Start change. Fall back to environment variables. getpwuid() fails on iOS.
String home = getenv("HOME");
String user = getenv("USER");
p.put("user.home", home != null ? home : "");
p.put("user.name", user != null ? user : "");
// RoboVM note: End change.
}
StructUtsname info = Libcore.os.uname();
p.put("os.arch", info.machine);
p.put("os.name", info.sysname);
p.put("os.version", info.release);
// Undocumented Android-only properties.
p.put("android.icu.library.version", ICU.getIcuVersion());
p.put("android.icu.unicode.version", ICU.getUnicodeVersion());
p.put("android.icu.cldr.version", ICU.getCldrVersion());
parsePropertyAssignments(p, specialProperties());
parsePropertyAssignments(p, robovmSpecialProperties());
// Override built-in properties with settings from the command line.
parsePropertyAssignments(p, runtime.properties());
systemProperties = p;
}
/**
* Returns an array of "key=value" strings containing information not otherwise
* easily available, such as #defined library versions.
*/
private static native String[] specialProperties();
private static native String[] robovmSpecialProperties();
/**
* Adds each element of 'assignments' to 'p', treating each element as an
* assignment in the form "key=value".
*/
private static void parsePropertyAssignments(Properties p, String[] assignments) {
for (String assignment : assignments) {
int split = assignment.indexOf('=');
String key = assignment.substring(0, split);
String value = assignment.substring(split + 1);
p.put(key, value);
}
}
/**
* Returns the value of a particular system property or {@code null} if no
* such property exists.
*
* The following properties are always provided by the Dalvik VM:
*
*
* Name Meaning Example
* file.separator {@link java.io.File#separator} {@code /} java.class.path System class path {@code .} java.class.version (Not useful on Android) {@code 50.0} java.compiler (Not useful on Android) Empty java.ext.dirs (Not useful on Android) Empty java.home Location of the VM on the file system {@code /system} java.io.tmpdir See {@link java.io.File#createTempFile} {@code /sdcard} java.library.path Search path for JNI libraries {@code /vendor/lib:/system/lib} java.vendor Human-readable VM vendor {@code The Android Project} java.vendor.url URL for VM vendor's web site {@code http://www.android.com/} java.version (Not useful on Android) {@code 0} java.specification.version VM libraries version {@code 0.9} java.specification.vendor VM libraries vendor {@code The Android Project} java.specification.name VM libraries name {@code Dalvik Core Library} java.vm.version VM implementation version {@code 1.2.0} java.vm.vendor VM implementation vendor {@code The Android Project} java.vm.name VM implementation name {@code Dalvik} java.vm.specification.version VM specification version {@code 0.9} java.vm.specification.vendor VM specification vendor {@code The Android Project} java.vm.specification.name VM specification name {@code Dalvik Virtual Machine Specification} line.separator The system line separator {@code \n} os.arch OS architecture {@code armv7l} os.name OS (kernel) name {@code Linux} os.version OS (kernel) version {@code 2.6.32.9-g103d848} path.separator See {@link java.io.File#pathSeparator} {@code :} user.dir Base of non-absolute paths {@code /} user.home (Not useful on Android) Empty user.name (Not useful on Android) Empty
*
* It is a mistake to try to override any of these. Doing so will have unpredictable results.
*
* @param propertyName
* the name of the system property to look up.
* @return the value of the specified system property or {@code null} if the
* property doesn't exist.
*/
public static String getProperty(String propertyName) {
return getProperty(propertyName, null);
}
/**
* Returns the value of a particular system property. The {@code
* defaultValue} will be returned if no such property has been found.
*/
public static String getProperty(String name, String defaultValue) {
checkPropertyName(name);
return getProperties().getProperty(name, defaultValue);
}
/**
* Sets the value of a particular system property.
*
* @return the old value of the property or {@code null} if the property
* didn't exist.
*/
public static String setProperty(String name, String value) {
checkPropertyName(name);
return (String) getProperties().setProperty(name, value);
}
/**
* Removes a specific system property.
*
* @return the property value or {@code null} if the property didn't exist.
* @throws NullPointerException
* if the argument is {@code null}.
* @throws IllegalArgumentException
* if the argument is empty.
*/
public static String clearProperty(String name) {
checkPropertyName(name);
return (String) getProperties().remove(name);
}
private static void checkPropertyName(String name) {
if (name == null) {
throw new NullPointerException("name == null");
}
if (name.isEmpty()) {
throw new IllegalArgumentException("name is empty");
}
}
/**
* Returns the {@link java.io.Console} associated with this VM, or null.
* Not all VMs will have an associated console. A console is typically only
* available for programs run from the command line.
* @since 1.6
*/
public static Console console() {
return Console.getConsole();
}
/**
* Returns null. Android does not use {@code SecurityManager}. This method
* is only provided for source compatibility.
*
* @return null
*/
public static SecurityManager getSecurityManager() {
return null;
}
/**
* Returns an integer hash code for the parameter. The hash code returned is
* the same one that would be returned by the method {@code
* java.lang.Object.hashCode()}, whether or not the object's class has
* overridden hashCode(). The hash code for {@code null} is {@code 0}.
*
* @param anObject
* the object to calculate the hash code.
* @return the hash code for the given object.
* @see java.lang.Object#hashCode
*/
public static native int identityHashCode(Object anObject);
/**
* Returns the system's line separator. On Android, this is {@code "\n"}. The value
* comes from the value of the {@code line.separator} system property when the VM
* starts. Later changes to the property will not affect the value returned by this
* method.
* @since 1.7
*/
public static String lineSeparator() {
return lineSeparator;
}
/**
* Loads and links the dynamic library that is identified through the
* specified path. This method is similar to {@link #loadLibrary(String)},
* but it accepts a full path specification whereas {@code loadLibrary} just
* accepts the name of the library to load.
*
* @param pathName
* the path of the file to be loaded.
*/
public static void load(String pathName) {
Runtime.getRuntime().load(pathName, VMStack.getCallingClassLoader());
}
/**
* Loads and links the library with the specified name. The mapping of the
* specified library name to the full path for loading the library is
* implementation-dependent.
*
* @param libName
* the name of the library to load.
* @throws UnsatisfiedLinkError
* if the library could not be loaded.
*/
public static void loadLibrary(String libName) {
Runtime.getRuntime().loadLibrary(libName, VMStack.getCallingClassLoader());
}
/**
* @hide internal use only
*/
public static void logE(String message) {
log('E', message, null);
}
/**
* @hide internal use only
*/
public static void logE(String message, Throwable th) {
log('E', message, th);
}
/**
* @hide internal use only
*/
public static void logI(String message) {
log('I', message, null);
}
/**
* @hide internal use only
*/
public static void logI(String message, Throwable th) {
log('I', message, th);
}
/**
* @hide internal use only
*/
public static void logW(String message) {
log('W', message, null);
}
/**
* @hide internal use only
*/
public static void logW(String message, Throwable th) {
log('W', message, th);
}
private static native void log(char type, String message, Throwable th);
/**
* Provides a hint to the VM that it would be useful to attempt
* to perform any outstanding object finalization.
*/
public static void runFinalization() {
Runtime.getRuntime().runFinalization();
}
/**
* Ensures that, when the VM is about to exit, all objects are
* finalized. Note that all finalization which occurs when the system is
* exiting is performed after all running threads have been terminated.
*
* @param flag
* the flag determines if finalization on exit is enabled.
* @deprecated This method is unsafe.
*/
@SuppressWarnings("deprecation")
@Deprecated
public static void runFinalizersOnExit(boolean flag) {
Runtime.runFinalizersOnExit(flag);
}
/**
* Sets all system properties. This does not take a copy; the passed-in object is used
* directly. Passing null causes the VM to reinitialize the properties to how they were
* when the VM was started.
*/
public static void setProperties(Properties p) {
systemProperties = p;
}
/**
* Throws {@code SecurityException}.
*
*
Security managers do not provide a secure environment for
* executing untrusted code and are unsupported on Android. Untrusted code
* cannot be safely isolated within a single VM on Android, so this method
* always throws a {@code SecurityException}.
*
* @param sm a security manager
* @throws SecurityException always
*/
public static void setSecurityManager(SecurityManager sm) {
if (sm != null) {
throw new SecurityException();
}
}
/**
* Returns the platform specific file name format for the shared library
* named by the argument.
*
* @param userLibName
* the name of the library to look up.
* @return the platform specific filename for the library.
*/
public static String mapLibraryName(String userLibName) {
if (userLibName == null) {
throw new NullPointerException("userLibName == null");
}
return mapLibraryName0(userLibName);
}
private static native String mapLibraryName0(String userLibName);
/**
* Sets the value of the named static field in the receiver to the passed in
* argument.
*
* @param fieldName
* the name of the field to set, one of in, out, or err
* @param stream
* the new value of the field
*/
private static native void setFieldImpl(String fieldName, String signature, Object stream);
/**
* The unmodifiable environment variables map. System.getenv() specifies
* that this map must throw when passed non-String keys.
*/
static class SystemEnvironment extends AbstractMap {
private final Map map;
public SystemEnvironment(Map map) {
this.map = Collections.unmodifiableMap(map);
}
@Override public Set> entrySet() {
return map.entrySet();
}
@Override public String get(Object key) {
return map.get(toNonNullString(key));
}
@Override public boolean containsKey(Object key) {
return map.containsKey(toNonNullString(key));
}
@Override public boolean containsValue(Object value) {
return map.containsValue(toNonNullString(value));
}
private String toNonNullString(Object o) {
if (o == null) {
throw new NullPointerException("o == null");
}
return (String) o;
}
}
}