Java Reference
In-Depth Information
23.2.3. ProcessBuilder
The exec methods of Runtime are convenience methods that use the more
general ProcessBuilder class. ProcessBuilder encapsulates the three key
attributes of an external process: the command, the environment, and
the current working directory. You can then start an external process
with those attributes by using the ProcessBuilder object's start method-
which returns a Process object, just as exec does.
ProcessBuilder has two constructors: One takes a sequence of String ob-
jects that represent the command; the other a List<String> that repres-
ents the command.
A fourth attribute you can control with ProcessBuilder , but not with exec ,
is whether the standard error stream of the process is redirected to
match the standard output stream of the process. Redirecting the error
stream merges all output into one stream, which makes it much easier
to correlate when errors occur relative to normal processing.
ProcessBuilder provides methods to query and set each of the four at-
tributes. Each query method simply names the attribute and returns
its valuefor example, command returns the current command as a
List<String> . The other query methods are
public File directory()
Returns the working directory.
public Map<String, String> environment()
Returns a map containing all the environment variable set-
tings
public boolean redirectErrorStream()
Returns true if the standard error stream should be redirected
to the standard output stream.
 
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