public abstract class Process extends Object
ProcessBuilder.start() and
 Runtime.exec
 methods create a native process and return an instance of a
 subclass of Process that can be used to control the process
 and obtain information about it.  The class Process
 provides methods for performing input from the process, performing
 output to the process, waiting for the process to complete,
 checking the exit status of the process, and destroying (killing)
 the process.
 The methods that create processes may not work well for special processes on certain native platforms, such as native windowing processes, daemon processes, Win16/DOS processes on Microsoft Windows, or shell scripts.
By default, the created subprocess does not have its own terminal
 or console.  All its standard I/O (i.e. stdin, stdout, stderr)
 operations will be redirected to the parent process, where they can
 be accessed via the streams obtained using the methods
 getOutputStream(),
 getInputStream(), and
 getErrorStream().
 The parent process uses these streams to feed input to and get output
 from the subprocess.  Because some native platforms only provide
 limited buffer size for standard input and output streams, failure
 to promptly write the input stream or read the output stream of
 the subprocess may cause the subprocess to block, or even deadlock.
 
Where desired, 
 subprocess I/O can also be redirected
 using methods of the ProcessBuilder class.
 
The subprocess is not killed when there are no more references to
 the Process object, but rather the subprocess
 continues executing asynchronously.
 
There is no requirement that a process represented by a Process object execute asynchronously or concurrently with respect
 to the Java process that owns the Process object.
 
As of 1.5, ProcessBuilder.start() is the preferred way
 to create a Process.
| Constructor and Description | 
|---|
| Process() | 
| Modifier and Type | Method and Description | 
|---|---|
| abstract void | destroy()Kills the subprocess. | 
| Process | destroyForcibly()Kills the subprocess. | 
| abstract int | exitValue()Returns the exit value for the subprocess. | 
| abstract InputStream | getErrorStream()Returns the input stream connected to the error output of the
 subprocess. | 
| abstract InputStream | getInputStream()Returns the input stream connected to the normal output of the
 subprocess. | 
| abstract OutputStream | getOutputStream()Returns the output stream connected to the normal input of the
 subprocess. | 
| boolean | isAlive()Tests whether the subprocess represented by this  Processis
 alive. | 
| abstract int | waitFor()Causes the current thread to wait, if necessary, until the
 process represented by this  Processobject has
 terminated. | 
| boolean | waitFor(long timeout,
       TimeUnit unit)Causes the current thread to wait, if necessary, until the
 subprocess represented by this  Processobject has
 terminated, or the specified waiting time elapses. | 
public abstract OutputStream getOutputStream()
Process object.
 If the standard input of the subprocess has been redirected using
 ProcessBuilder.redirectInput
 then this method will return a
 null output stream.
 
Implementation note: It is a good idea for the returned output stream to be buffered.
public abstract InputStream getInputStream()
Process object.
 If the standard output of the subprocess has been redirected using
 ProcessBuilder.redirectOutput
 then this method will return a
 null input stream.
 
Otherwise, if the standard error of the subprocess has been
 redirected using
 ProcessBuilder.redirectErrorStream
 then the input stream returned by this method will receive the
 merged standard output and the standard error of the subprocess.
 
Implementation note: It is a good idea for the returned input stream to be buffered.
public abstract InputStream getErrorStream()
Process object.
 If the standard error of the subprocess has been redirected using
 ProcessBuilder.redirectError or
 ProcessBuilder.redirectErrorStream
 then this method will return a
 null input stream.
 
Implementation note: It is a good idea for the returned input stream to be buffered.
public abstract int waitFor()
                     throws InterruptedException
Process object has
 terminated.  This method returns immediately if the subprocess
 has already terminated.  If the subprocess has not yet
 terminated, the calling thread will be blocked until the
 subprocess exits.Process object.  By convention, the value
         0 indicates normal termination.InterruptedException - if the current thread is
         interrupted by another
         thread while it is waiting, then the wait is ended and
         an InterruptedException is thrown.public boolean waitFor(long timeout,
                       TimeUnit unit)
                throws InterruptedException
Process object has
 terminated, or the specified waiting time elapses.
 If the subprocess has already terminated then this method returns
 immediately with the value true.  If the process has not
 terminated and the timeout value is less than, or equal to, zero, then
 this method returns immediately with the value false.
 
The default implementation of this methods polls the exitValue
 to check if the process has terminated. Concrete implementations of this
 class are strongly encouraged to override this method with a more
 efficient implementation.
timeout - the maximum time to waitunit - the time unit of the timeout argumenttrue if the subprocess has exited and false if
         the waiting time elapsed before the subprocess has exited.InterruptedException - if the current thread is interrupted
         while waiting.NullPointerException - if unit is nullpublic abstract int exitValue()
Process object.  By convention, the value
         0 indicates normal termination.IllegalThreadStateException - if the subprocess represented
         by this Process object has not yet terminatedpublic abstract void destroy()
Process object is forcibly terminated or not is
 implementation dependent.public Process destroyForcibly()
Process object is forcibly terminated.
 The default implementation of this method invokes destroy()
 and so may not forcibly terminate the process. Concrete implementations
 of this class are strongly encouraged to override this method with a
 compliant implementation.  Invoking this method on Process
 objects returned by ProcessBuilder.start() and
 Runtime.exec(java.lang.String) will forcibly terminate the process.
 
Note: The subprocess may not terminate immediately.
 i.e. isAlive() may return true for a brief period
 after destroyForcibly() is called. This method
 may be chained to waitFor() if needed.
Process object representing the
         subprocess to be forcibly destroyed.public boolean isAlive()
Process is
 alive.true if the subprocess represented by this
         Process object has not yet terminated. Submit a bug or feature 
For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
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