Interface CLIBeanSpec

All Superinterfaces:

ConfigBeanSpec

@ClassVersion(sourceVersion="$Id: CLIBeanSpec.java 1164 2026-03-20 17:38:18Z tquadrat $")
@API(status=STABLE,
     since="0.0.1")
public interface CLIBeanSpec
extends ConfigBeanSpec

When a configuration bean should be initialised from the command line, the respective specification interface needs to extend this interface.

If none of the getters in the extended interface is annotated with either @Option or @Argument, the compilation failed because the generated class does not implement the methods from this interface (dumpParamFileTemplate(OutputStream), parseCommandLine(String[]), printUsage(OutputStream, CharSequence) and retrieveParseErrorMessage()). The error message will be something like "<Generated Class> is not abstract".

Author:

Thomas Thrien (thomas.thrien@tquadrat.org)

Version:

$Id: CLIBeanSpec.java 1164 2026-03-20 17:38:18Z tquadrat $

Since:

0.0.1

UML Diagram

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UML Diagram for "org.tquadrat.foundation.config.CLIBeanSpec"

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Field Summary

Fields

Modifier and Type	Field	Description
static final String	ARG_FILE_ESCAPE	The escape character for argument files: "@".
static final String	LEAD_IN	The lead-in character for an option name: "-".

Method Summary

Modifier and Type	Method	Description
void	dumpParamFileTemplate(OutputStream outputStream)	Dumps a parameter file template to the given OutputStream.
boolean	parseCommandLine(String[] args)	Parses the command line.
void	printUsage(OutputStream outputStream, CharSequence command)	Prints a usage message to the given OutputStream.
Optional<String>	retrieveParseErrorMessage()	Retrieves the message for the error caused by the last call to parseCommandLine(String[]), given that this return false.

Methods inherited from interface ConfigBeanSpec

addListener, getCharset, getLocale, getResourceBundle, getTimezone, isDebug, isTest, removeListener, setCharset, setLocale, setTimezone

Field Details

ARG_FILE_ESCAPE

static final String ARG_FILE_ESCAPE

The escape character for argument files: "@".

See Also:

• Constant Field Values

LEAD_IN

static final String LEAD_IN

The lead-in character for an option name: "-".

See Also:

• Constant Field Values

Method Details

dumpParamFileTemplate

void dumpParamFileTemplate(OutputStream outputStream)
                    throws IOException

Dumps a parameter file template to the given OutputStream.

Parameters:

outputStream - The target output stream.

Throws:

IOException - Something went wrong when writing to the output stream.

See Also:

• parseCommandLine(String[])

parseCommandLine

boolean parseCommandLine(String[] args)

Parses the command line.

As a result from parsing the given command line arguments, the accordingly annotated properties will be initialised with the values from the command line.

Arguments starting with @ (like @param.lst) are treated as a file that contains further arguments.

Assuming the file param.lst has the following contents:

-opt0
value0
-opt1
value1
--
arg0
arg1

and args looks like this:

-opt value @param.lst arg

,

the resulting command line arguments set would be:

-opt value -opt0 value0 -opt1 value1 -- arg0 arg1 arg

In case the file could not be opened for whatever reason, the parameter will not be replaced – meaning the resulting command line would have the value @param.lst as one value.

Parameters:

args - The command line arguments; usually the same as the arguments to the method main().

Returns:

true if the command line could be parsed without issues, false otherwise.

printUsage

void printUsage(OutputStream outputStream,
 CharSequence command)
         throws IOException

Prints a usage message to the given OutputStream.

Parameters:

outputStream - The output stream.

command - The command used to start the program.

Throws:

IOException - A problem occurred on writing to the output stream.

retrieveParseErrorMessage

Optional<String> retrieveParseErrorMessage()

Retrieves the message for the error caused by the last call to parseCommandLine(String[]), given that this return false.

Returns:

An instance of Optional that holds the error message.