de.susebox.java.lang

Interface Environment

All Known Implementing Classes:

DefaultEnvironment

public interface Environment

A Environment object is a substitute for the usual environment as defined in the System class, most important the stdin and stdout channels System.in and System.out.

Environments are especially useful in classes that can be used both standalone (having a main method) or in an application where the class is only one of many. Another scenario would be a simple class designed for use from the command line that should suddenly be invoked in GUI framework without redirecting the default channels System.in and System.out.

To obtain an Environment instance or to store such instances use the class EnvironmentProvider:

    Environment env = EnvironmentProvider.getEnvironment(this);

Author:

Heiko Blau

Method Summary

Modifier and Type	Method and Description
java.io.PrintStream	err() This method returns the substitution for System.err, the standard error channel.
void	exit() This method exits the instance of its Environment implementation.
int	getExitStatus() Retrieving the currently set exit code.
java.io.InputStream	in() This method returns the substitution for System.in, the standard input channel.
java.io.PrintStream	out() This method returns the substitution for System.out, the standard output channel.
void	setExitStatus(int status) During different stages of program execution various exit codes can be set using this method.

Method Detail

in

java.io.InputStream in()
                throws java.lang.UnsupportedOperationException

This method returns the substitution for System.in, the standard input channel. Instead of a public member like in the System class, we prefer the method version since it is more flexible.

Returns:

the InputStream that serves as standard input

Throws:

java.lang.UnsupportedOperationException - if there is no stdin channel available

See Also:

System.in

out

java.io.PrintStream out()
                 throws java.lang.UnsupportedOperationException

This method returns the substitution for System.out, the standard output channel. Instead of a public member like in the System class, we prefer the method version since it is more flexible.

Returns:

the PrintStream that serves as standard output

Throws:

java.lang.UnsupportedOperationException - if there is no stdout channel available

See Also:

System.out

err

java.io.PrintStream err()
                 throws java.lang.UnsupportedOperationException

This method returns the substitution for System.err, the standard error channel. Instead of a public member like in the System class, we prefer the method version since it is more flexible.

Returns:

the PrintStream that serves as standard error output

Throws:

java.lang.UnsupportedOperationException - if there is no stderr channel available

See Also:

System.err

setExitStatus

void setExitStatus(int status)

During different stages of program execution various exit codes can be set using this method. For instance, a program may set the exit code to a positive number indicating that it is still running. A negative exit code may stand for errors while 0 is the usual OK code.

Parameters:

status - the exit code of an application

See Also:

System.exit(int), getExitStatus(), exit()

getExitStatus

int getExitStatus()

Retrieving the currently set exit code.

Returns:

the currently set exit code of an application

exit

void exit()
   throws java.lang.UnsupportedOperationException

This method exits the instance of its Environment implementation. After calling exit the Environment instance is generally not any longer usable. In particular, an implementation can choose to call System.exit(int).

Throws:

java.lang.UnsupportedOperationException - if the method is not available

See Also:

setExitStatus(int), System.exit(int)