gt:             Version that = (Version)ob;
context: /*
   * Copyright (c) 1995, 2016, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.  Oracle designates this
   * particular file as subject to the "Classpath" exception as provided
   * by Oracle in the LICENSE file that accompanied this code.
   *
   * This code is distributed in the hope that it will be useful, but WITHOUT
   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
   * version 2 for more details (a copy is included in the LICENSE file that
   * accompanied this code).
   *
   * You should have received a copy of the GNU General Public License version
   * 2 along with this work; if not, write to the Free Software Foundation,
   * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
   * or visit www.oracle.com if you need additional information or have any
   * questions.
   */
  
  package java.lang;
  
  import java.io.*;
  import java.math.BigInteger;
  import java.util.ArrayList;
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  import java.util.stream.Collectors;
  import java.util.Collections;
  import java.util.List;
  import java.util.Optional;
  import java.util.StringTokenizer;
  import jdk.internal.reflect.CallerSensitive;
  import jdk.internal.reflect.Reflection;
  
  /**
   * Every Java application has a single instance of class
   * {@code Runtime} that allows the application to interface with
   * the environment in which the application is running. The current
   * runtime can be obtained from the {@code getRuntime} method.
   * <p>
   * An application cannot create its own instance of this class.
   *
   * @author  unascribed
   * @see     java.lang.Runtime#getRuntime()
   * @since   1.0
   */
  
  public class Runtime {
      private static final Runtime currentRuntime = new Runtime();
  
      private static Version version;
  
      /**
       * Returns the runtime object associated with the current Java application.
       * Most of the methods of class {@code Runtime} are instance
       * methods and must be invoked with respect to the current runtime object.
       *
       * @return  the {@code Runtime} object associated with the current
       *          Java application.
       */
      public static Runtime getRuntime() {
          return currentRuntime;
      }
  
      /** Don't let anyone else instantiate this class */
      private Runtime() {}
  
      /**
       * Terminates the currently running Java virtual machine by initiating its
       * shutdown sequence.  This method never returns normally.  The argument
       * serves as a status code; by convention, a nonzero status code indicates
       * abnormal termination.
       *
       * <p> The virtual machine's shutdown sequence consists of two phases.  In
       * the first phase all registered {@link #addShutdownHook shutdown hooks},
       * if any, are started in some unspecified order and allowed to run
       * concurrently until they finish.  In the second phase all uninvoked
       * finalizers are run if {@link #runFinalizersOnExit finalization-on-exit}
       * has been enabled.  Once this is done the virtual machine {@link #halt halts}.
       *
       * <p> If this method is invoked after the virtual machine has begun its
       * shutdown sequence then if shutdown hooks are being run this method will
       * block indefinitely.  If shutdown hooks have already been run and on-exit
       * finalization has been enabled then this method halts the virtual machine
       * with the given status code if the status is nonzero; otherwise, it
       * blocks indefinitely.
       *
       * <p> The {@link System#exit(int) System.exit} method is the
       * conventional and convenient means of invoking this method.
       *
       * @param  status
       *         Termination status.  By convention, a nonzero status code
       *         indicates abnormal termination.
       *
       * @throws SecurityException
       *         If a security manager is present and its
       *         {@link SecurityManager#checkExit checkExit} method does not permit
       *         exiting with the specified status
       *
       * @see java.lang.SecurityException
       * @see java.lang.SecurityManager#checkExit(int)
       * @see #addShutdownHook
       * @see #removeShutdownHook
       * @see #runFinalizersOnExit
       * @see #halt(int)
       */
      public void exit(int status) {
          SecurityManager security = System.getSecurityManager();
          if (security != null) {
              security.checkExit(status);
          }
          Shutdown.exit(status);
      }
  
      /**
       * Registers a new virtual-machine shutdown hook.
       *
       * <p> The Java virtual machine <i>shuts down</i> in response to two kinds
       * of events:
       *
       *   <ul>
       *
       *   <li> The program <i>exits</i> normally, when the last non-daemon
       *   thread exits or when the {@link #exit exit} (equivalently,
       *   {@link System#exit(int) System.exit}) method is invoked, or
       *
       *   <li> The virtual machine is <i>terminated</i> in response to a
       *   user interrupt, such as typing {@code ^C}, or a system-wide event,
       *   such as user logoff or system shutdown.
       *
       *   </ul>
       *
       * <p> A <i>shutdown hook</i> is simply an initialized but unstarted
       * thread.  When the virtual machine begins its shutdown sequence it will
       * start all registered shutdown hooks in some unspecified order and let
       * them run concurrently.  When all the hooks have finished it will then
       * run all uninvoked finalizers if finalization-on-exit has been enabled.
       * Finally, the virtual machine will halt.  Note that daemon threads will
       * continue to run during the shutdown sequence, as will non-daemon threads
       * if shutdown was initiated by invoking the {@link #exit exit} method.
       *
       * <p> Once the shutdown sequence has begun it can be stopped only by
       * invoking the {@link #halt halt} method, which forcibly
       * terminates the virtual machine.
       *
       * <p> Once the shutdown sequence has begun it is impossible to register a
       * new shutdown hook or de-register a previously-registered hook.
       * Attempting either of these operations will cause an
       * {@link IllegalStateException} to be thrown.
       *
       * <p> Shutdown hooks run at a delicate time in the life cycle of a virtual
       * machine and should therefore be coded defensively.  They should, in
       * particular, be written to be thread-safe and to avoid deadlocks insofar
       * as possible.  They should also not rely blindly upon services that may
       * have registered their own shutdown hooks and therefore may themselves in
       * the process of shutting down.  Attempts to use other thread-based
       * services such as the AWT event-dispatch thread, for example, may lead to
       * deadlocks.
       *
       * <p> Shutdown hooks should also finish their work quickly.  When a
       * program invokes {@link #exit exit} the expectation is
       * that the virtual machine will promptly shut down and exit.  When the
       * virtual machine is terminated due to user logoff or system shutdown the
       * underlying operating system may only allow a fixed amount of time in
       * which to shut down and exit.  It is therefore inadvisable to attempt any
       * user interaction or to perform a long-running computation in a shutdown
       * hook.
       *
       * <p> Uncaught exceptions are handled in shutdown hooks just as in any
       * other thread, by invoking the
       * {@link ThreadGroup#uncaughtException uncaughtException} method of the
       * thread's {@link ThreadGroup} object. The default implementation of this
       * method prints the exception's stack trace to {@link System#err} and
       * terminates the thread; it does not cause the virtual machine to exit or
       * halt.
       *
       * <p> In rare circumstances the virtual machine may <i>abort</i>, that is,
       * stop running without shutting down cleanly.  This occurs when the
       * virtual machine is terminated externally, for example with the
       * {@code SIGKILL} signal on Unix or the {@code TerminateProcess} call on
       * Microsoft Windows.  The virtual machine may also abort if a native
       * method goes awry by, for example, corrupting internal data structures or
       * attempting to access nonexistent memory.  If the virtual machine aborts
       * then no guarantee can be made about whether or not any shutdown hooks
       * will be run.
       *
       * @param   hook
       *          An initialized but unstarted {@link Thread} object
       *
       * @throws  IllegalArgumentException
       *          If the specified hook has already been registered,
       *          or if it can be determined that the hook is already running or
       *          has already been run
       *
       * @throws  IllegalStateException
       *          If the virtual machine is already in the process
       *          of shutting down
       *
       * @throws  SecurityException
       *          If a security manager is present and it denies
       *          {@link RuntimePermission}("shutdownHooks")
       *
       * @see #removeShutdownHook
       * @see #halt(int)
       * @see #exit(int)
       * @since 1.3
       */
      public void addShutdownHook(Thread hook) {
          SecurityManager sm = System.getSecurityManager();
          if (sm != null) {
              sm.checkPermission(new RuntimePermission("shutdownHooks"));
          }
          ApplicationShutdownHooks.add(hook);
      }
  
      /**
       * De-registers a previously-registered virtual-machine shutdown hook.
       *
       * @param hook the hook to remove
       * @return {@code true} if the specified hook had previously been
       * registered and was successfully de-registered, {@code false}
       * otherwise.
       *
       * @throws  IllegalStateException
       *          If the virtual machine is already in the process of shutting
       *          down
       *
       * @throws  SecurityException
       *          If a security manager is present and it denies
       *          {@link RuntimePermission}("shutdownHooks")
       *
       * @see #addShutdownHook
       * @see #exit(int)
       * @since 1.3
       */
      public boolean removeShutdownHook(Thread hook) {
          SecurityManager sm = System.getSecurityManager();
          if (sm != null) {
              sm.checkPermission(new RuntimePermission("shutdownHooks"));
          }
          return ApplicationShutdownHooks.remove(hook);
      }
  
      /**
       * Forcibly terminates the currently running Java virtual machine.  This
       * method never returns normally.
       *
       * <p> This method should be used with extreme caution.  Unlike the
       * {@link #exit exit} method, this method does not cause shutdown
       * hooks to be started and does not run uninvoked finalizers if
       * finalization-on-exit has been enabled.  If the shutdown sequence has
       * already been initiated then this method does not wait for any running
       * shutdown hooks or finalizers to finish their work.
       *
       * @param  status
       *         Termination status. By convention, a nonzero status code
       *         indicates abnormal termination. If the {@link Runtime#exit exit}
       *         (equivalently, {@link System#exit(int) System.exit}) method
       *         has already been invoked then this status code
       *         will override the status code passed to that method.
       *
       * @throws SecurityException
       *         If a security manager is present and its
       *         {@link SecurityManager#checkExit checkExit} method
       *         does not permit an exit with the specified status
       *
       * @see #exit
       * @see #addShutdownHook
       * @see #removeShutdownHook
       * @since 1.3
       */
      public void halt(int status) {
          SecurityManager sm = System.getSecurityManager();
          if (sm != null) {
              sm.checkExit(status);
          }
          Shutdown.halt(status);
      }
  
      /**
       * Enable or disable finalization on exit; doing so specifies that the
       * finalizers of all objects that have finalizers that have not yet been
       * automatically invoked are to be run before the Java runtime exits.
       * By default, finalization on exit is disabled.
       *
       * <p>If there is a security manager,
       * its {@code checkExit} method is first called
       * with 0 as its argument to ensure the exit is allowed.
       * This could result in a SecurityException.
       *
       * @param value true to enable finalization on exit, false to disable
       * @deprecated  This method is inherently unsafe.  It may result in
       *      finalizers being called on live objects while other threads are
       *      concurrently manipulating those objects, resulting in erratic
       *      behavior or deadlock.
       *      This method is subject to removal in a future version of Java SE.
       *
       * @throws  SecurityException
       *        if a security manager exists and its {@code checkExit}
       *        method doesn't allow the exit.
       *
       * @see     java.lang.Runtime#exit(int)
       * @see     java.lang.Runtime#gc()
       * @see     java.lang.SecurityManager#checkExit(int)
       * @since   1.1
       */
      @Deprecated(since="1.2", forRemoval=true)
      public static void runFinalizersOnExit(boolean value) {
          SecurityManager security = System.getSecurityManager();
          if (security != null) {
              try {
                  security.checkExit(0);
              } catch (SecurityException e) {
                  throw new SecurityException("runFinalizersOnExit");
              }
          }
          Shutdown.setRunFinalizersOnExit(value);
      }
  
      /**
       * Executes the specified string command in a separate process.
       *
       * <p>This is a convenience method.  An invocation of the form
       * {@code exec(command)}
       * behaves in exactly the same way as the invocation
       * {@link #exec(String, String[], File) exec}{@code (command, null, null)}.
       *
       * @param   command   a specified system command.
       *
       * @return  A new {@link Process} object for managing the subprocess
       *
       * @throws  SecurityException
       *          If a security manager exists and its
       *          {@link SecurityManager#checkExec checkExec}
       *          method doesn't allow creation of the subprocess
       *
       * @throws  IOException
       *          If an I/O error occurs
       *
       * @throws  NullPointerException
       *          If {@code command} is {@code null}
       *
       * @throws  IllegalArgumentException
       *          If {@code command} is empty
       *
       * @see     #exec(String[], String[], File)
       * @see     ProcessBuilder
       */
      public Process exec(String command) throws IOException {
          return exec(command, null, null);
      }
  
      /**
       * Executes the specified string command in a separate process with the
       * specified environment.
       *
       * <p>This is a convenience method.  An invocation of the form
       * {@code exec(command, envp)}
       * behaves in exactly the same way as the invocation
       * {@link #exec(String, String[], File) exec}{@code (command, envp, null)}.
       *
       * @param   command   a specified system command.
       *
       * @param   envp      array of strings, each element of which
       *                    has environment variable settings in the format
       *                    <i>name</i>=<i>value</i>, or
       *                    {@code null} if the subprocess should inherit
       *                    the environment of the current process.
       *
       * @return  A new {@link Process} object for managing the subprocess
       *
       * @throws  SecurityException
       *          If a security manager exists and its
       *          {@link SecurityManager#checkExec checkExec}
       *          method doesn't allow creation of the subprocess
       *
       * @throws  IOException
       *          If an I/O error occurs
       *
       * @throws  NullPointerException
       *          If {@code command} is {@code null},
       *          or one of the elements of {@code envp} is {@code null}
       *
       * @throws  IllegalArgumentException
       *          If {@code command} is empty
       *
       * @see     #exec(String[], String[], File)
       * @see     ProcessBuilder
       */
      public Process exec(String command, String[] envp) throws IOException {
          return exec(command, envp, null);
      }
  
      /**
       * Executes the specified string command in a separate process with the
       * specified environment and working directory.
       *
       * <p>This is a convenience method.  An invocation of the form
       * {@code exec(command, envp, dir)}
       * behaves in exactly the same way as the invocation
       * {@link #exec(String[], String[], File) exec}{@code (cmdarray, envp, dir)},
       * where {@code cmdarray} is an array of all the tokens in
       * {@code command}.
       *
       * <p>More precisely, the {@code command} string is broken
       * into tokens using a {@link StringTokenizer} created by the call
       * {@code new {@link StringTokenizer}(command)} with no
       * further modification of the character categories.  The tokens
       * produced by the tokenizer are then placed in the new string
       * array {@code cmdarray}, in the same order.
       *
       * @param   command   a specified system command.
       *
       * @param   envp      array of strings, each element of which
       *                    has environment variable settings in the format
       *                    <i>name</i>=<i>value</i>, or
       *                    {@code null} if the subprocess should inherit
       *                    the environment of the current process.
       *
       * @param   dir       the working directory of the subprocess, or
       *                    {@code null} if the subprocess should inherit
       *                    the working directory of the current process.
       *
       * @return  A new {@link Process} object for managing the subprocess
       *
       * @throws  SecurityException
       *          If a security manager exists and its
       *          {@link SecurityManager#checkExec checkExec}
       *          method doesn't allow creation of the subprocess
       *
       * @throws  IOException
       *          If an I/O error occurs
       *
       * @throws  NullPointerException
       *          If {@code command} is {@code null},
       *          or one of the elements of {@code envp} is {@code null}
       *
       * @throws  IllegalArgumentException
       *          If {@code command} is empty
       *
       * @see     ProcessBuilder
       * @since 1.3
       */
      public Process exec(String command, String[] envp, File dir)
          throws IOException {
          if (command.length() == 0)
              throw new IllegalArgumentException("Empty command");
  
          StringTokenizer st = new StringTokenizer(command);
          String[] cmdarray = new String[st.countTokens()];
          for (int i = 0; st.hasMoreTokens(); i++)
              cmdarray[i] = st.nextToken();
          return exec(cmdarray, envp, dir);
      }
  
      /**
       * Executes the specified command and arguments in a separate process.
       *
       * <p>This is a convenience method.  An invocation of the form
       * {@code exec(cmdarray)}
       * behaves in exactly the same way as the invocation
       * {@link #exec(String[], String[], File) exec}{@code (cmdarray, null, null)}.
       *
       * @param   cmdarray  array containing the command to call and
       *                    its arguments.
       *
       * @return  A new {@link Process} object for managing the subprocess
       *
       * @throws  SecurityException
       *          If a security manager exists and its
       *          {@link SecurityManager#checkExec checkExec}
       *          method doesn't allow creation of the subprocess
       *
       * @throws  IOException
       *          If an I/O error occurs
       *
       * @throws  NullPointerException
       *          If {@code cmdarray} is {@code null},
       *          or one of the elements of {@code cmdarray} is {@code null}
       *
       * @throws  IndexOutOfBoundsException
       *          If {@code cmdarray} is an empty array
       *          (has length {@code 0})
       *
       * @see     ProcessBuilder
       */
      public Process exec(String cmdarray[]) throws IOException {
          return exec(cmdarray, null, null);
      }
  
      /**
       * Executes the specified command and arguments in a separate process
       * with the specified environment.
       *
       * <p>This is a convenience method.  An invocation of the form
       * {@code exec(cmdarray, envp)}
       * behaves in exactly the same way as the invocation
       * {@link #exec(String[], String[], File) exec}{@code (cmdarray, envp, null)}.
       *
       * @param   cmdarray  array containing the command to call and
       *                    its arguments.
       *
       * @param   envp      array of strings, each element of which
       *                    has environment variable settings in the format
       *                    <i>name</i>=<i>value</i>, or
       *                    {@code null} if the subprocess should inherit
       *                    the environment of the current process.
       *
       * @return  A new {@link Process} object for managing the subprocess
       *
       * @throws  SecurityException
       *          If a security manager exists and its
       *          {@link SecurityManager#checkExec checkExec}
       *          method doesn't allow creation of the subprocess
       *
       * @throws  IOException
       *          If an I/O error occurs
       *
       * @throws  NullPointerException
       *          If {@code cmdarray} is {@code null},
       *          or one of the elements of {@code cmdarray} is {@code null},
       *          or one of the elements of {@code envp} is {@code null}
       *
       * @throws  IndexOutOfBoundsException
       *          If {@code cmdarray} is an empty array
       *          (has length {@code 0})
       *
       * @see     ProcessBuilder
       */
      public Process exec(String[] cmdarray, String[] envp) throws IOException {
          return exec(cmdarray, envp, null);
      }
  
  
      /**
       * Executes the specified command and arguments in a separate process with
       * the specified environment and working directory.
       *
       * <p>Given an array of strings {@code cmdarray}, representing the
       * tokens of a command line, and an array of strings {@code envp},
       * representing "environment" variable settings, this method creates
       * a new process in which to execute the specified command.
       *
       * <p>This method checks that {@code cmdarray} is a valid operating
       * system command.  Which commands are valid is system-dependent,
       * but at the very least the command must be a non-empty list of
       * non-null strings.
       *
       * <p>If {@code envp} is {@code null}, the subprocess inherits the
       * environment settings of the current process.
       *
       * <p>A minimal set of system dependent environment variables may
       * be required to start a process on some operating systems.
       * As a result, the subprocess may inherit additional environment variable
       * settings beyond those in the specified environment.
       *
       * <p>{@link ProcessBuilder#start()} is now the preferred way to
       * start a process with a modified environment.
       *
       * <p>The working directory of the new subprocess is specified by {@code dir}.
       * If {@code dir} is {@code null}, the subprocess inherits the
       * current working directory of the current process.
       *
       * <p>If a security manager exists, its
       * {@link SecurityManager#checkExec checkExec}
       * method is invoked with the first component of the array
       * {@code cmdarray} as its argument. This may result in a
       * {@link SecurityException} being thrown.
       *
       * <p>Starting an operating system process is highly system-dependent.
       * Among the many things that can go wrong are:
       * <ul>
       * <li>The operating system program file was not found.
       * <li>Access to the program file was denied.
       * <li>The working directory does not exist.
       * </ul>
       *
       * <p>In such cases an exception will be thrown.  The exact nature
       * of the exception is system-dependent, but it will always be a
       * subclass of {@link IOException}.
       *
       * <p>If the operating system does not support the creation of
       * processes, an {@link UnsupportedOperationException} will be thrown.
       *
       *
       * @param   cmdarray  array containing the command to call and
       *                    its arguments.
       *
       * @param   envp      array of strings, each element of which
       *                    has environment variable settings in the format
       *                    <i>name</i>=<i>value</i>, or
       *                    {@code null} if the subprocess should inherit
       *                    the environment of the current process.
       *
       * @param   dir       the working directory of the subprocess, or
       *                    {@code null} if the subprocess should inherit
       *                    the working directory of the current process.
       *
       * @return  A new {@link Process} object for managing the subprocess
       *
       * @throws  SecurityException
       *          If a security manager exists and its
       *          {@link SecurityManager#checkExec checkExec}
       *          method doesn't allow creation of the subprocess
       *
       * @throws  UnsupportedOperationException
       *          If the operating system does not support the creation of processes.
       *
       * @throws  IOException
       *          If an I/O error occurs
       *
       * @throws  NullPointerException
       *          If {@code cmdarray} is {@code null},
       *          or one of the elements of {@code cmdarray} is {@code null},
       *          or one of the elements of {@code envp} is {@code null}
       *
       * @throws  IndexOutOfBoundsException
       *          If {@code cmdarray} is an empty array
       *          (has length {@code 0})
       *
       * @see     ProcessBuilder
       * @since 1.3
       */
      public Process exec(String[] cmdarray, String[] envp, File dir)
          throws IOException {
          return new ProcessBuilder(cmdarray)
              .environment(envp)
              .directory(dir)
              .start();
      }
  
      /**
       * Returns the number of processors available to the Java virtual machine.
       *
       * <p> This value may change during a particular invocation of the virtual
       * machine.  Applications that are sensitive to the number of available
       * processors should therefore occasionally poll this property and adjust
       * their resource usage appropriately. </p>
       *
       * @return  the maximum number of processors available to the virtual
       *          machine; never smaller than one
       * @since 1.4
       */
      public native int availableProcessors();
  
      /**
       * Returns the amount of free memory in the Java Virtual Machine.
       * Calling the
       * {@code gc} method may result in increasing the value returned
       * by {@code freeMemory.}
       *
       * @return  an approximation to the total amount of memory currently
       *          available for future allocated objects, measured in bytes.
       */
      public native long freeMemory();
  
      /**
       * Returns the total amount of memory in the Java virtual machine.
       * The value returned by this method may vary over time, depending on
       * the host environment.
       * <p>
       * Note that the amount of memory required to hold an object of any
       * given type may be implementation-dependent.
       *
       * @return  the total amount of memory currently available for current
       *          and future objects, measured in bytes.
       */
      public native long totalMemory();
  
      /**
       * Returns the maximum amount of memory that the Java virtual machine
       * will attempt to use.  If there is no inherent limit then the value
       * {@link java.lang.Long#MAX_VALUE} will be returned.
       *
       * @return  the maximum amount of memory that the virtual machine will
       *          attempt to use, measured in bytes
       * @since 1.4
       */
      public native long maxMemory();
  
      /**
       * Runs the garbage collector.
       * Calling this method suggests that the Java virtual machine expend
       * effort toward recycling unused objects in order to make the memory
       * they currently occupy available for quick reuse. When control
       * returns from the method call, the virtual machine has made
       * its best effort to recycle all discarded objects.
       * <p>
       * The name {@code gc} stands for "garbage
       * collector". The virtual machine performs this recycling
       * process automatically as needed, in a separate thread, even if the
       * {@code gc} method is not invoked explicitly.
       * <p>
       * The method {@link System#gc()} is the conventional and convenient
       * means of invoking this method.
       */
      public native void gc();
  
      /* Wormhole for calling java.lang.ref.Finalizer.runFinalization */
      private static native void runFinalization0();
  
      /**
       * Runs the finalization methods of any objects pending finalization.
       * Calling this method suggests that the Java virtual machine expend
       * effort toward running the {@code finalize} methods of objects
       * that have been found to be discarded but whose {@code finalize}
       * methods have not yet been run. When control returns from the
       * method call, the virtual machine has made a best effort to
       * complete all outstanding finalizations.
       * <p>
       * The virtual machine performs the finalization process
       * automatically as needed, in a separate thread, if the
       * {@code runFinalization} method is not invoked explicitly.
       * <p>
       * The method {@link System#runFinalization()} is the conventional
       * and convenient means of invoking this method.
       *
       * @see     java.lang.Object#finalize()
       */
      public void runFinalization() {
          runFinalization0();
      }
  
      /**
       * Not implemented, does nothing.
       *
       * @deprecated
       * This method was intended to control instruction tracing.
       * It has been superseded by JVM-specific tracing mechanisms.
       *
       * @param on ignored
       */
      @Deprecated(since="9", forRemoval=true)
      public void traceInstructions(boolean on) { }
  
      /**
       * Not implemented, does nothing.
       *
       * @deprecated
       * This method was intended to control method call tracing.
       * It has been superseded by JVM-specific tracing mechanisms.
       *
       * @param on ignored
       */
      @Deprecated(since="9", forRemoval=true)
      public void traceMethodCalls(boolean on) { }
  
      /**
       * Loads the native library specified by the filename argument.  The filename
       * argument must be an absolute path name.
       * (for example
       * {@code Runtime.getRuntime().load("/home/avh/lib/libX11.so");}).
       *
       * If the filename argument, when stripped of any platform-specific library
       * prefix, path, and file extension, indicates a library whose name is,
       * for example, L, and a native library called L is statically linked
       * with the VM, then the JNI_OnLoad_L function exported by the library
       * is invoked rather than attempting to load a dynamic library.
       * A filename matching the argument does not have to exist in the file
       * system. See the JNI Specification for more details.
       *
       * Otherwise, the filename argument is mapped to a native library image in
       * an implementation-dependent manner.
       * <p>
       * First, if there is a security manager, its {@code checkLink}
       * method is called with the {@code filename} as its argument.
       * This may result in a security exception.
       * <p>
       * This is similar to the method {@link #loadLibrary(String)}, but it
       * accepts a general file name as an argument rather than just a library
       * name, allowing any file of native code to be loaded.
       * <p>
       * The method {@link System#load(String)} is the conventional and
       * convenient means of invoking this method.
       *
       * @param      filename   the file to load.
       * @exception  SecurityException  if a security manager exists and its
       *             {@code checkLink} method doesn't allow
       *             loading of the specified dynamic library
       * @exception  UnsatisfiedLinkError  if either the filename is not an
       *             absolute path name, the native library is not statically
       *             linked with the VM, or the library cannot be mapped to
       *             a native library image by the host system.
       * @exception  NullPointerException if {@code filename} is
       *             {@code null}
       * @see        java.lang.Runtime#getRuntime()
       * @see        java.lang.SecurityException
       * @see        java.lang.SecurityManager#checkLink(java.lang.String)
       */
      @CallerSensitive
      public void load(String filename) {
          load0(Reflection.getCallerClass(), filename);
      }
  
      synchronized void load0(Class<?> fromClass, String filename) {
          SecurityManager security = System.getSecurityManager();
          if (security != null) {
              security.checkLink(filename);
          }
          if (!(new File(filename).isAbsolute())) {
              throw new UnsatisfiedLinkError(
                  "Expecting an absolute path of the library: " + filename);
          }
          ClassLoader.loadLibrary(fromClass, filename, true);
      }
  
      /**
       * Loads the native library specified by the {@code libname}
       * argument.  The {@code libname} argument must not contain any platform
       * specific prefix, file extension or path. If a native library
       * called {@code libname} is statically linked with the VM, then the
       * JNI_OnLoad_{@code libname} function exported by the library is invoked.
       * See the JNI Specification for more details.
       *
       * Otherwise, the libname argument is loaded from a system library
       * location and mapped to a native library image in an implementation-
       * dependent manner.
       * <p>
       * First, if there is a security manager, its {@code checkLink}
       * method is called with the {@code libname} as its argument.
       * This may result in a security exception.
       * <p>
       * The method {@link System#loadLibrary(String)} is the conventional
       * and convenient means of invoking this method. If native
       * methods are to be used in the implementation of a class, a standard
       * strategy is to put the native code in a library file (call it
       * {@code LibFile}) and then to put a static initializer:
       * <blockquote><pre>
       * static { System.loadLibrary("LibFile"); }
       * </pre></blockquote>
       * within the class declaration. When the class is loaded and
       * initialized, the necessary native code implementation for the native
       * methods will then be loaded as well.
       * <p>
       * If this method is called more than once with the same library
       * name, the second and subsequent calls are ignored.
       *
       * @param      libname   the name of the library.
       * @exception  SecurityException  if a security manager exists and its
       *             {@code checkLink} method doesn't allow
       *             loading of the specified dynamic library
       * @exception  UnsatisfiedLinkError if either the libname argument
       *             contains a file path, the native library is not statically
       *             linked with the VM,  or the library cannot be mapped to a
       *             native library image by the host system.
       * @exception  NullPointerException if {@code libname} is
       *             {@code null}
       * @see        java.lang.SecurityException
       * @see        java.lang.SecurityManager#checkLink(java.lang.String)
       */
      @CallerSensitive
      public void loadLibrary(String libname) {
          loadLibrary0(Reflection.getCallerClass(), libname);
      }
  
      synchronized void loadLibrary0(Class<?> fromClass, String libname) {
          SecurityManager security = System.getSecurityManager();
          if (security != null) {
              security.checkLink(libname);
          }
          if (libname.indexOf((int)File.separatorChar) != -1) {
              throw new UnsatisfiedLinkError(
      "Directory separator should not appear in library name: " + libname);
          }
          ClassLoader.loadLibrary(fromClass, libname, false);
      }
  
      /**
       * Creates a localized version of an input stream. This method takes
       * an {@code InputStream} and returns an {@code InputStream}
       * equivalent to the argument in all respects except that it is
       * localized: as characters in the local character set are read from
       * the stream, they are automatically converted from the local
       * character set to Unicode.
       * <p>
       * If the argument is already a localized stream, it may be returned
       * as the result.
       *
       * @param      in InputStream to localize
       * @return     a localized input stream
       * @see        java.io.InputStream
       * @see        java.io.BufferedReader#BufferedReader(java.io.Reader)
       * @see        java.io.InputStreamReader#InputStreamReader(java.io.InputStream)
       * @deprecated As of JDK&nbsp;1.1, the preferred way to translate a byte
       * stream in the local encoding into a character stream in Unicode is via
       * the {@code InputStreamReader} and {@code BufferedReader}
       * classes.
       * This method is subject to removal in a future version of Java SE.
       */
      @Deprecated(since="1.1", forRemoval=true)
      public InputStream getLocalizedInputStream(InputStream in) {
          return in;
      }
  
      /**
       * Creates a localized version of an output stream. This method
       * takes an {@code OutputStream} and returns an
       * {@code OutputStream} equivalent to the argument in all respects
       * except that it is localized: as Unicode characters are written to
       * the stream, they are automatically converted to the local
       * character set.
       * <p>
       * If the argument is already a localized stream, it may be returned
       * as the result.
       *
       * @deprecated As of JDK&nbsp;1.1, the preferred way to translate a
       * Unicode character stream into a byte stream in the local encoding is via
       * the {@code OutputStreamWriter}, {@code BufferedWriter}, and
       * {@code PrintWriter} classes.
       * This method is subject to removal in a future version of Java SE.
       *
       * @param      out OutputStream to localize
       * @return     a localized output stream
       * @see        java.io.OutputStream
       * @see        java.io.BufferedWriter#BufferedWriter(java.io.Writer)
       * @see        java.io.OutputStreamWriter#OutputStreamWriter(java.io.OutputStream)
       * @see        java.io.PrintWriter#PrintWriter(java.io.OutputStream)
       */
      @Deprecated(since="1.1", forRemoval=true)
      public OutputStream getLocalizedOutputStream(OutputStream out) {
          return out;
      }
  
      /**
       * Returns the version of the Java Runtime Environment as a {@link
       * Runtime.Version}.
       *
       * @return  the {@link Runtime.Version} of the Java Runtime Environment
       *
       * @since  9
       */
      public static Version version() {
          if (version == null) {
              version = new Version(VersionProps.versionNumbers(),
                      VersionProps.pre(), VersionProps.build(),
                      VersionProps.optional());
          }
          return version;
      }
  
      /**
       * A representation of a version string for an implementation of the
       * Java&nbsp;SE Platform.  A version string contains a version number
       * optionally followed by pre-release and build information.
       *
       * <h2><a name="verNum">Version numbers</a></h2>
       *
       * <p> A <em>version number</em>, {@code $VNUM}, is a non-empty sequence
       * of elements separated by period characters (U+002E).  An element is
       * either zero, or a unsigned integer numeral without leading zeros.  The
       * final element in a version number must not be zero.  The format is:
       * </p>
       *
       * <blockquote><pre>
       *     ^[1-9][0-9]*(((\.0)*\.[1-9][0-9]*)*)*$
       * </pre></blockquote>
       *
       * <p> The sequence may be of arbitrary length but the first three
       * elements are assigned specific meanings, as follows:</p>
       *
       * <blockquote><pre>
       *     $MAJOR.$MINOR.$SECURITY
       * </pre></blockquote>
       *
       * <ul>
       *
       * <li><p> <a name="major">{@code $MAJOR}</a> --- The major version
       * number, incremented for a major release that contains significant new
       * features as specified in a new edition of the Java&#160;SE Platform
       * Specification, <em>e.g.</em>, <a
       * href="https://jcp.org/en/jsr/detail?id=337">JSR 337</a> for
       * Java&#160;SE&#160;8.  Features may be removed in a major release, given
       * advance notice at least one major release ahead of time, and
       * incompatible changes may be made when justified. The {@code $MAJOR}
       * version number of JDK&#160;8 is {@code 8}; the {@code $MAJOR} version
       * number of JDK&#160;9 is {@code 9}.  When {@code $MAJOR} is incremented,
       * all subsequent elements are removed. </p></li>
       *
       * <li><p> <a name="minor">{@code $MINOR}</a> --- The minor version
       * number, incremented for a minor update release that may contain
       * compatible bug fixes, revisions to standard APIs mandated by a
       * <a href="https://jcp.org/en/procedures/jcp2#5.3">Maintenance Release</a>
       * of the relevant Platform Specification, and implementation features
       * outside the scope of that Specification such as new JDK-specific APIs,
       * additional service providers, new garbage collectors, and ports to new
       * hardware architectures. </p></li>
       *
       * <li><p> <a name="security">{@code $SECURITY}</a> --- The security
       * level, incremented for a security update release that contains critical
       * fixes including those necessary to improve security.  {@code $SECURITY}
       * is <strong>not</strong> reset when {@code $MINOR} is incremented.  A
       * higher value of {@code $SECURITY} for a given {@code $MAJOR} value,
       * therefore, always indicates a more secure release, regardless of the
       * value of {@code $MINOR}. </p></li>
       *
       * </ul>
       *
       * <p> The fourth and later elements of a version number are free for use
       * by downstream consumers of this code base.  Such a consumer may,
       * <em>e.g.</em>, use the fourth element to identify patch releases which
       * contain a small number of critical non-security fixes in addition to
       * the security fixes in the corresponding security release. </p>
       *
       * <p> The version number does not include trailing zero elements;
       * <em>i.e.</em>, {@code $SECURITY} is omitted if it has the value zero,
       * and {@code $MINOR} is omitted if both {@code $MINOR} and {@code
       * $SECURITY} have the value zero. </p>
       *
       * <p> The sequence of numerals in a version number is compared to another
       * such sequence in numerical, pointwise fashion; <em>e.g.</em>, {@code
       * 9.9.1} is less than {@code 9.10.3}. If one sequence is shorter than
       * another then the missing elements of the shorter sequence are
       * considered to be less than the corresponding elements of the longer
       * sequence; <em>e.g.</em>, {@code 9.1.2} is less than {@code 9.1.2.1}.
       * </p>
       *
       * <h2><a name="verStr">Version strings</a></h2>
       *
       * <p> A <em>version string</em>, {@code $VSTR}, consists of a version
       * number {@code $VNUM}, as described above, optionally followed by
       * pre-release and build information, in the format </p>
       *
       * <blockquote><pre>
       *     $VNUM(-$PRE)?(\+($BUILD)?(-$OPT)?)?
       * </pre></blockquote>
       *
       * <p> where: </p>
       *
       * <ul>
       *
       * <li><p> <a name="pre">{@code $PRE}</a>, matching {@code ([a-zA-Z0-9]+)}
       * --- A pre-release identifier.  Typically {@code ea}, for a
       * potentially unstable early-access release under active development,
       * or {@code internal}, for an internal developer build.
       *
       * <li><p> <a name="build">{@code $BUILD}</a>, matching {@code
       * (0|[1-9][0-9]*)} --- The build number, incremented for each promoted
       * build.  {@code $BUILD} is reset to {@code 1} when any portion of {@code
       * $VNUM} is incremented. </p>
       *
       * <li><p> <a name="opt">{@code $OPT}</a>, matching {@code
       * ([-a-zA-Z0-9\.]+)} --- Additional build information, if desired.  In
       * the case of an {@code internal} build this will often contain the date
       * and time of the build. </p>
       *
       * </ul>
       *
       * <p> A version number {@code 10-ea} matches {@code $VNUM = "10"} and
       * {@code $PRE = "ea"}.  The version number {@code 10+-ea} matches
       * {@code $VNUM = "10"} and {@code $OPT = "ea"}. </p>
       *
       * <p> When comparing two version strings, the value of {@code $OPT}, if
       * present, may or may not be significant depending on the chosen
       * comparison method.  The comparison methods {@link #compareTo(Version)
       * compareTo()} and {@link #compareToIgnoreOptional(Version)
       * compareToIgnoreOptional()} should be used consistently with the
       * corresponding methods {@link #equals(Object) equals()} and {@link
       * #equalsIgnoreOptional(Object) equalsIgnoreOptional()}.  </p>
       *
       * <p> A <em>short version string</em>, {@code $SVSTR}, often useful in
       * less formal contexts, is a version number optionally followed by a
       * pre-release identifier:
       *
       * <blockquote><pre>
       *     $VNUM(-$PRE)?
       * </pre></blockquote>
       *
       * @since  9
       */
      public static class Version
          implements Comparable<Version>
      {
          private final List<Integer>     version;
          private final Optional<String>  pre;
          private final Optional<Integer> build;
          private final Optional<String>  optional;
  
          Version(List<Integer> version, Optional<String> pre,
                  Optional<Integer> build, Optional<String> optional) {
              this.version = Collections.unmodifiableList(version);
              this.pre = pre;
              this.build = build;
              this.optional = optional;
          }
  
          /**
           * Parses the given string as a valid
           * <a href="#verStr">version string</a> containing a
           * <a href="#verNum">version number</a> followed by pre-release and
           * build information.
           *
           * @param  s
           *         A string to interpret as a version
           *
           * @throws  IllegalArgumentException
           *          If the given string cannot be interpreted as a valid
           *          version
           *
           * @throws  NullPointerException
           *          If the given string is {@code null}
           *
           * @throws  NumberFormatException
           *          If an element of the version number or the build number
           *          cannot be represented as an {@link Integer}
           *
           * @return  The Version of the given string
           */
          public static Version parse(String s) {
              if (s == null)
                  throw new NullPointerException();
  
              // Shortcut to avoid initializing VersionPattern when creating
              // major version constants during startup
              if (isSimpleNumber(s)) {
                  return new Version(List.of(Integer.parseInt(s)),
                          Optional.empty(), Optional.empty(), Optional.empty());
              }
              Matcher m = VersionPattern.VSTR_PATTERN.matcher(s);
              if (!m.matches())
                  throw new IllegalArgumentException("Invalid version string: '"
                                                     + s + "'");
  
              // $VNUM is a dot-separated list of integers of arbitrary length
              List<Integer> version = new ArrayList<>();
              for (String i : m.group(VersionPattern.VNUM_GROUP).split("\\."))
                  version.add(Integer.parseInt(i));
  
              Optional<String> pre = Optional.ofNullable(
                      m.group(VersionPattern.PRE_GROUP));
  
              String b = m.group(VersionPattern.BUILD_GROUP);
              // $BUILD is an integer
              Optional<Integer> build = (b == null)
                  ? Optional.empty()
                  : Optional.of(Integer.parseInt(b));
  
              Optional<String> optional = Optional.ofNullable(
                      m.group(VersionPattern.OPT_GROUP));
  
              // empty '+'
              if ((m.group(VersionPattern.PLUS_GROUP) != null)
                      && !build.isPresent()) {
                  if (optional.isPresent()) {
                      if (pre.isPresent())
                          throw new IllegalArgumentException("'+' found with"
                              + " pre-release and optional components:'" + s
                              + "'");
                  } else {
                      throw new IllegalArgumentException("'+' found with neither"
                          + " build or optional components: '" + s + "'");
                  }
              }
              return new Version(version, pre, build, optional);
          }
  
          private static boolean isSimpleNumber(String s) {
              for (int i = 0; i < s.length(); i++) {
                  char c = s.charAt(i);
                  char lowerBound = (i > 0) ? '0' : '1';
                  if (c < lowerBound || c > '9') {
                      return false;
                  }
              }
              return true;
          }
  
          /**
           * Returns the <a href="#major">major</a> version number.
           *
           * @return  The major version number
           */
          public int major() {
              return version.get(0);
          }
  
          /**
           * Returns the <a href="#minor">minor</a> version number or zero if it
           * was not set.
           *
           * @return  The minor version number or zero if it was not set
           */
          public int minor() {
              return (version.size() > 1 ? version.get(1) : 0);
          }
  
          /**
           * Returns the <a href="#security">security</a> version number or zero
           * if it was not set.
           *
           * @return  The security version number or zero if it was not set
           */
          public int security() {
              return (version.size() > 2 ? version.get(2) : 0);
          }
  
          /**
           * Returns an unmodifiable {@link java.util.List List} of the
           * integer numerals contained in the <a href="#verNum">version
           * number</a>.  The {@code List} always contains at least one
           * element corresponding to the <a href="#major">major version
           * number</a>.
           *
           * @return  An unmodifiable list of the integer numerals
           *          contained in the version number
           */
          public List<Integer> version() {
              return version;
          }
  
          /**
           * Returns the optional <a href="#pre">pre-release</a> information.
           *
           * @return  The optional pre-release information as a String
           */
          public Optional<String> pre() {
              return pre;
          }
  
          /**
           * Returns the <a href="#build">build number</a>.
           *
           * @return  The optional build number.
           */
          public Optional<Integer> build() {
              return build;
          }
  
          /**
           * Returns <a href="#opt">optional</a> additional identifying build
           * information.
           *
           * @return  Additional build information as a String
           */
          public Optional<String> optional() {
              return optional;
          }
  
          /**
           * Compares this version to another.
           *
           * <p> Each of the components in the <a href="#verStr">version</a> is
           * compared in the follow order of precedence: version numbers,
           * pre-release identifiers, build numbers, optional build information.
           * </p>
           *
           * <p> Comparison begins by examining the sequence of version numbers.
           * If one sequence is shorter than another, then the missing elements
           * of the shorter sequence are considered to be less than the
           * corresponding elements of the longer sequence. </p>
           *
           * <p> A version with a pre-release identifier is always considered to
           * be less than a version without one.  Pre-release identifiers are
           * compared numerically when they consist only of digits, and
           * lexicographically otherwise.  Numeric identifiers are considered to
           * be less than non-numeric identifiers.  </p>
           *
           * <p> A version without a build number is always less than one with a
           * build number; otherwise build numbers are compared numerically. </p>
           *
           * <p> The optional build information is compared lexicographically.
           * During this comparison, a version with optional build information is
           * considered to be greater than a version without one. </p>
           *
           * <p> A version is not comparable to any other type of object.
           *
           * @param  ob
           *         The object to be compared
           *
           * @return  A negative integer, zero, or a positive integer if this
           *          {@code Version} is less than, equal to, or greater than the
           *          given {@code Version}
           *
           * @throws  NullPointerException
           *          If the given object is {@code null}
           */
          @Override
          public int compareTo(Version ob) {
              return compare(ob, false);
          }
  
          /**
           * Compares this version to another disregarding optional build
           * information.
           *
           * <p> Two versions are compared by examining the version string as
           * described in {@link #compareTo(Version)} with the exception that the
           * optional build information is always ignored. </p>
           *
           * <p> A version is not comparable to any other type of object.
           *
           * @param  ob
           *         The object to be compared
           *
           * @return  A negative integer, zero, or a positive integer if this
           *          {@code Version} is less than, equal to, or greater than the
           *          given {@code Version}
           *
           * @throws  NullPointerException
           *          If the given object is {@code null}
           */
          public int compareToIgnoreOptional(Version ob) {
              return compare(ob, true);
          }
  
          private int compare(Version ob, boolean ignoreOpt) {
              if (ob == null)
                  throw new NullPointerException("Invalid argument");
  
              int ret = compareVersion(ob);
              if (ret != 0)
                  return ret;
  
              ret = comparePre(ob);
              if (ret != 0)
                  return ret;
  
              ret = compareBuild(ob);
              if (ret != 0)
                  return ret;
  
              if (!ignoreOpt)
                  return compareOptional(ob);
  
              return 0;
          }
  
          private int compareVersion(Version ob) {
              int size = version.size();
              int oSize = ob.version().size();
              int min = Math.min(size, oSize);
              for (int i = 0; i < min; i++) {
                  Integer val = version.get(i);
                  Integer oVal = ob.version().get(i);
                  if (val != oVal)
                      return val - oVal;
              }
              if (size != oSize)
                  return size - oSize;
              return 0;
          }
  
          private int comparePre(Version ob) {
              Optional<String> oPre = ob.pre();
              if (!pre.isPresent()) {
                  if (oPre.isPresent())
                      return 1;
              } else {
                  if (!oPre.isPresent())
                      return -1;
                  String val = pre.get();
                  String oVal = oPre.get();
                  if (val.matches("\\d+")) {
                      return (oVal.matches("\\d+")
                          ? (new BigInteger(val)).compareTo(new BigInteger(oVal))
                          : -1);
                  } else {
                      return (oVal.matches("\\d+")
                          ? 1
                          : val.compareTo(oVal));
                  }
              }
              return 0;
          }
  
          private int compareBuild(Version ob) {
              Optional<Integer> oBuild = ob.build();
              if (oBuild.isPresent()) {
                  return (build.isPresent()
                          ? build.get().compareTo(oBuild.get())
                          : 1);
              } else if (build.isPresent()) {
                  return -1;
              }
              return 0;
          }
  
          private int compareOptional(Version ob) {
              Optional<String> oOpt = ob.optional();
              if (!optional.isPresent()) {
                  if (oOpt.isPresent())
                      return -1;
              } else {
                  if (!oOpt.isPresent())
                      return 1;
                  return optional.get().compareTo(oOpt.get());
              }
              return 0;
          }
  
          /**
           * Returns a string representation of this version.
           *
           * @return  The version string
           */
          @Override
          public String toString() {
              StringBuilder sb
                  = new StringBuilder(version.stream()
                      .map(Object::toString)
                      .collect(Collectors.joining(".")));
  
              pre.ifPresent(v -> sb.append("-").append(v));
  
              if (build.isPresent()) {
                  sb.append("+").append(build.get());
                  if (optional.isPresent())
                      sb.append("-").append(optional.get());
              } else {
                  if (optional.isPresent()) {
                      sb.append(pre.isPresent() ? "-" : "+-");
                      sb.append(optional.get());
                  }
              }
  
              return sb.toString();
          }
  
          /**
           * Determines whether this {@code Version} is equal to another object.
           *
           * <p> Two {@code Version}s are equal if and only if they represent the
           * same version string.
           *
           * <p> This method satisfies the general contract of the {@link
           * Object#equals(Object) Object.equals} method. </p>
           *
           * @param  ob
           *         The object to which this {@code Version} is to be compared
           *
           * @return  {@code true} if, and only if, the given object is a {@code
           *          Version} that is identical to this {@code Version}
           *
           */
          @Override
          public boolean equals(Object ob) {
              boolean ret = equalsIgnoreOptional(ob);
              if (!ret)
                  return false;
  
  