uk.ac.starlink.task

Class ChoiceParameter<T>

java.lang.Object

uk.ac.starlink.task.Parameter<T>

uk.ac.starlink.task.AbstractChoiceParameter<T,T>

uk.ac.starlink.task.ChoiceParameter<T>

Direct Known Subclasses:

CombinerParameter, DataStoreParameter, FindModeParameter, JoinFixActionParameter, JoinTypeParameter, LayerTypeParameter, PaintModeParameter, ProgressIndicatorParameter, RowRunnerParameter, StyleParameter

public class ChoiceParameter<T>
extends AbstractChoiceParameter<T,T>

Parameter whose legal value must be one of a disjunction of given values. Matching is case-insensitive against the stringified value of the option.

Since:

15 Aug 2005

Author:

Mark Taylor

Field Summary

Fields inherited from class uk.ac.starlink.task.Parameter

BY_NAME

Constructor Summary

Constructors

Constructor and Description
ChoiceParameter(String name, Class<T> clazz) Constructs a choice parameter with no initially set options.
ChoiceParameter(String name, Class<T> clazz, T[] options) Constructor.
ChoiceParameter(String name, T[] options) Constructs a choice parameter with an initial option set.

Method Summary

Modifier and Type	Method and Description
String	getUsage() Returns a usage message.
String	objectToString(Environment env, T objVal) Takes a typed value of this parameter and formats it as a string which may be used for presentation to the user.
void	setDefaultOption(T option) Sets the default value for this parameter to one of the previously added options.
void	setUsage(String usage) Sets a usage string for this parameter.
T	stringToObject(Environment env, String sval) Takes a non-blank string, as supplied by the execution environment, and turns it into a typed value for this parameter.

Methods inherited from class uk.ac.starlink.task.AbstractChoiceParameter

addOption, addOption, choiceToString, clearOptions, getName, getOption, getOptionNames, getOptions, getOptionValueList, stringifyOption, stringToChoice

Methods inherited from class uk.ac.starlink.task.Parameter

clearValue, getDescription, getName, getPosition, getPreferExplicit, getPrompt, getStringDefault, getValueClass, isNullPermitted, objectValue, setDescription, setDescription, setName, setNullPermitted, setPosition, setPreferExplicit, setPrompt, setStringDefault, setValue, setValueFromObject, setValueFromString, stringValue, toArray, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

ChoiceParameter

public ChoiceParameter(String name,
                       Class<T> clazz,
                       T[] options)

Constructor.

Parameters:

name - parameter name

clazz - type for values of this parameter

options - initial array of legal values of this parameter

ChoiceParameter

public ChoiceParameter(String name,
                       Class<T> clazz)

Constructs a choice parameter with no initially set options.

Parameters:

name - parameter name

clazz - type for values of this parameter

ChoiceParameter

public ChoiceParameter(String name,
                       T[] options)

Constructs a choice parameter with an initial option set. The data type is taken from the supplied array type.

Parameters:

name - parameter name

options - initial array of legal values of this parameter

Method Detail

stringToObject

public T stringToObject(Environment env,
                        String sval)
                 throws TaskException

Description copied from class: Parameter

Takes a non-blank string, as supplied by the execution environment, and turns it into a typed value for this parameter. This method also performs validation, so if the string value is unacceptable in any way, a ParameterValueException should be thrown.

It is an error to supply a null or empty string value.

If this method fails (throws a ParameterValueException) and if allowClassnameValue is set, then a subsequent attempt will be made to interpret the stringVal as the classname of a suitable class with a no-arg constructor.

Specified by:

stringToObject in class Parameter<T>

Parameters:

env - execution environment; in most cases this is not required but for some purposes environment-specific characteristics may influence the result

sval - non-null, non-empty string value

Returns:

typed value

Throws:

TaskException

objectToString

public String objectToString(Environment env,
                             T objVal)

Description copied from class: Parameter

Takes a typed value of this parameter and formats it as a string which may be used for presentation to the user. Ideally, round-tripping between this method and stringToObject should be possible, but that is not in general required/guaranteed.

The default implementation uses the value's toString method, but subclasses can override this for smarter behaviour.

Overrides:

objectToString in class Parameter<T>

Parameters:

env - execution environment

objVal - typed parameter value

Returns:

string value for presentation

getUsage

public String getUsage()

Returns a usage message. Unless it has been overriden by an earlier call to setUsage(java.lang.String), this will return a usage message based on the list of known options.

Overrides:

getUsage in class Parameter<T>

Returns:

usage message

See Also:

Parameter.setUsage(java.lang.String)

setUsage

public void setUsage(String usage)

Description copied from class: Parameter

Sets a usage string for this parameter. This should be terse (in particular no newline characters) and conform to the following rules:

• the parameter name is not included in the message
• placeholders are enclosed in angle brackets (<>)
• literals are not enclosed in angle brackets
• a disjunction is represented using the "|" character

The Parameter class uses the string "<value>" as the default usage string.

Overrides:

setUsage in class Parameter<T>

Parameters:

usage - usage string

setDefaultOption

public void setDefaultOption(T option)

Sets the default value for this parameter to one of the previously added options.

Parameters:

option - default option