gcc/libjava/java/lang/Process.java

/* Process.java - Represent spawned system process
   Copyright (C) 1998, 1999, 2001, 2002 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
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General Public License for more details.

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Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA.

Linking this library statically or dynamically with other modules is
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As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
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terms of your choice, provided that you also meet, for each linked
independent module, the terms and conditions of the license of that
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package java.lang;

import java.io.OutputStream;
import java.io.InputStream;

/**
 * An instance of a subclass of <code>Process</code> is created by the
 * <code>Runtime.exec</code> methods.  Methods in <code>Process</code>
 * provide a means to send input to a process, obtain the output from a
 * subprocess, destroy a subprocess, obtain the exit value from a
 * subprocess, and wait for a subprocess to complete.
 *
 * <p>This is dependent on the platform, and some processes (like native
 * windowing processes, 16-bit processes in Windows, or shell scripts) may
 * be limited in functionality. Because some platforms have limited buffers
 * between processes, you may need to provide input and read output to prevent
 * the process from blocking, or even deadlocking.
 *
 * <p>Even if all references to this object disapper, the process continues
 * to execute to completion. There are no guarantees that the
 * subprocess execute asynchronously or concurrently with the process which
 * owns this object.
 *
 * @author Brian Jones
 * @author Tom Tromey <tromey@cygnus.com>
 * @see Runtime#exec(String[], String[], File)
 * @since 1.0
 * @status updated to 1.4
 */
public abstract class Process
{
  /**
   * Empty constructor does nothing.
   */
  public Process()
  {
  }

  /**
   * Obtain the output stream that sends data to the subprocess. This is
   * the STDIN of the subprocess. When implementing, you should probably
   * use a buffered stream.
   *
   * @return the output stream that pipes to the process input
   */
  public abstract OutputStream getOutputStream();

  /**
   * Obtain the input stream that receives data from the subprocess. This is
   * the STDOUT of the subprocess. When implementing, you should probably
   * use a buffered stream.
   *
   * @return the input stream that pipes data from the process output
   */
  public abstract InputStream getInputStream();

  /**
   * Obtain the input stream that receives data from the subprocess. This is
   * the STDERR of the subprocess. When implementing, you should probably
   * use a buffered stream.
   *
   * @return the input stream that pipes data from the process error output
   */
  public abstract InputStream getErrorStream();

  /**
   * The thread calling <code>waitFor</code> will block until the subprocess
   * has terminated. If the process has already terminated then the method
   * immediately returns with the exit value of the subprocess.
   *
   * @return the subprocess exit value; 0 conventionally denotes success
   * @throws InterruptedException if another thread interrups the blocked one
   */
  public abstract int waitFor() throws InterruptedException;

  /**
   * When a process terminates there is associated with that termination
   * an exit value for the process to indicate why it terminated. A return
   * of <code>0</code> denotes normal process termination by convention.
   *
   * @return the exit value of the subprocess
   * @throws IllegalThreadStateException if the subprocess has not terminated
   */
  public abstract int exitValue();

  /**
   * Kills the subprocess and all of its children forcibly.
   */
  public abstract void destroy();
} // class Process