org.unix4j.command

Class NoOp

java.lang.Object

org.unix4j.command.AbstractCommand<NoOp.Args>

org.unix4j.command.NoOp

All Implemented Interfaces:

Command<NoOp.Args>

public class NoOp
extends AbstractCommand<NoOp.Args>

A command that performs no operation. Useful as initial command in a CommandBuilder. The join(Command) method returns the joined command only, that is, this nop command is eliminated.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	NoOp.Args Arguments for NoOp.

Field Summary

Fields

Modifier and Type	Field and Description
static NoOp	INSTANCE The singleton instance.
static String	NAME The "nop" command name.

Method Summary

Methods

Modifier and Type	Method and Description
LineProcessor	execute(ExecutionContext context, LineProcessor output) Executes this command and returns a LineProcessor object.
Command<?>	join(Command<?> next) Returns the given next command eliminating this NoOp command in a join.

Methods inherited from class org.unix4j.command.AbstractCommand

getArguments, getName, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

NAME

public static final String NAME

The "nop" command name.

See Also:

Constant Field Values

INSTANCE

public static final NoOp INSTANCE

The singleton instance.

Method Detail

join

public Command<?> join(Command<?> next)

Returns the given next command eliminating this NoOp command in a join.

Specified by:

join in interface Command<NoOp.Args>

Overrides:

join in class AbstractCommand<NoOp.Args>

Parameters:

next - the next command to join to this command

Returns:

the next command argument

execute

public LineProcessor execute(ExecutionContext context,
                    LineProcessor output)

Description copied from interface: Command

Executes this command and returns a LineProcessor object. Calling this method initiates the command execution, but the real processing of the command takes place when lines are passed to the returned LineProcessor object. The command execution is terminated by calling LineProcessor.finish().

The command writes its output to the specified output object. Depending on the command implementation, the output is written when lines are passed to the LineProcessor returned by this method, or when the execution terminates with the finish() call.

Parameters:

context - context object providing access to the current directory, environment variables and other information useful for the command during its execution

output - the output to write to

Returns:

true if another invocation with more input is expected, and false if this command has completed and no other invocation is required.