org.unix4j.io

Class NullOutput

java.lang.Object

org.unix4j.io.NullOutput

All Implemented Interfaces:

Output, LineProcessor

public class NullOutput
extends Object
implements Output

Output device writing to /dev/null, which means that all lines written to this device are ignored.

Two instances are available, the ABORT instance which returns false when processLine(Line) which usually causes the program execution to abort. The DEFAULT instance does not abort program execution to make sure that no side effects are suppressed.

Field Summary

Fields

Modifier and Type	Field and Description
static NullOutput	ABORT Aborting instance returning false when processLine(Line) is called.
static NullOutput	DEFAULT Default instance returning true when processLine(Line) is called.

Constructor Summary

Constructors

Constructor and Description
NullOutput(boolean abort) NOTE: application code should normally use the DEFAULT or ABORT constants instead of this constructor.

Method Summary

Modifier and Type	Method and Description
void	finish() Indicates that all output has been written.
boolean	processLine(Line line) Writes a line to the output.
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT

public static final NullOutput DEFAULT

Default instance returning true when processLine(Line) is called. This ensures that a command does not abort early and it is guaranteed that no (possibly important) side effects are missed.

ABORT

public static final NullOutput ABORT

Aborting instance returning false when processLine(Line) is called. Note that most commands will abort their execution early with this output device and some (possibly important) side effects could be missed.

Constructor Detail

NullOutput

public NullOutput(boolean abort)

NOTE: application code should normally use the DEFAULT or ABORT constants instead of this constructor.

The abort flag passed to this constructor indicates whether the process can be aborted early or not; abort=true means that the method processLine(Line) returns false indicating that this device does not expect any more input lines. Most commands will abort their execution early in this case, which means that (possibly important) side effects are missed.

Parameters:

abort - a flag indicating whether command execution can be aborted early

Method Detail

processLine

public boolean processLine(Line line)

Description copied from interface: Output

Writes a line to the output.

Specified by:

processLine in interface Output

Specified by:

processLine in interface LineProcessor

Parameters:

line - the line to write to the output.

Returns:

true if this Output device is ready to process more lines, and false otherwise; output devices usually return true

finish

public void finish()

Description copied from interface: Output

Indicates that all output has been written. Usually triggers a flush operation or closes the underlying reader or stream.

Specified by:

finish in interface Output

Specified by:

finish in interface LineProcessor

toString

public String toString()

Overrides:

toString in class Object