Module java.base
Package java.lang

Class Process


public abstract class Process extends Object
Process provides control of native processes started by ProcessBuilder.start and Runtime.exec. The class 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 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 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 process 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 I/O streams of characters and lines can be written and read using the methods outputWriter(), outputWriter(Charset)}, inputReader(), inputReader(Charset), errorReader(), and errorReader(Charset). The parent process uses these streams to feed input to and get output from the process. 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 process may cause the process to block, or even deadlock.

Where desired, process I/O can also be redirected using methods of the ProcessBuilder class.

The process is not killed when there are no more references to the Process object, but rather the process continues executing asynchronously.

There is no requirement that the 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.

Subclasses of Process should override the onExit() and toHandle() methods to provide a fully functional Process including the process id, information about the process, direct children, and direct children plus descendants of those children of the process. Delegating to the underlying Process or ProcessHandle is typically easiest and most efficient.