ToggleNullConfigKey (Starjava TTOOLS API)

java.lang.Object
- uk.ac.starlink.ttools.plot2.config.ConfigKey<T>
- - uk.ac.starlink.ttools.plot2.config.ToggleNullConfigKey<T>

```
public class ToggleNullConfigKey<T>
extends ConfigKey<T>
```
Wraps a supplied ConfigKey to provide one that will also allow selection of the null value. In the GUI, this is represented with a toggle button that when selected indicates null, and when not defers to the usual specifier GUI.
This is intended for use with config keys that do not normally accept null values. If used with config keys that do permit null values, confusion may result.

Since:

29 Jun 2016

Author:

Mark Taylor

Constructor Summary

Constructors
Constructor Description

ToggleNullConfigKey(ConfigKey<T> baseKey, java.lang.String toggleLabel, boolean toggleDflt)
Constructor.

Constructors
Constructor	Description
`ToggleNullConfigKey(ConfigKey<T> baseKey, java.lang.String toggleLabel, boolean toggleDflt)`	Constructor.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`Specifier<T>`	`createSpecifier()`	Constructs a graphical control with which the user can specify a suitable value for association with this key.
`T`	`stringToValue(java.lang.String txt)`	Decodes a string value to the value type of this key.
`java.lang.String`	`valueToString(T value)`	Reports a value as a string.

Methods inherited from class uk.ac.starlink.ttools.plot2.config.ConfigKey
cast, getDefaultValue, getMeta, getValueClass, toString

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

- Constructor Detail
  - ToggleNullConfigKey
```
public ToggleNullConfigKey(ConfigKey<T> baseKey,
                           java.lang.String toggleLabel,
                           boolean toggleDflt)
```
    Constructor.
    
    Parameters:
    
    baseKey - config key providing non-null-valued behaviour
    
    toggleLabel - GUI label for the toggle button selecting null
    
    toggleDflt - true if the default is null, false if the default is that of the base key
- Method Detail
  - valueToString
```
public java.lang.String valueToString(T value)
```
    Description copied from class: ConfigKey
    
    Reports a value as a string. If at all possible the roundtripping should be possible, so stringToValue(valueToString(v)).equals(v). A null value, if permitted, should be represented as an empty string.
    
    Specified by:
    
    valueToString in class ConfigKey<T>
    
    Parameters:
    
    value - possible value associated with this key
    
    Returns:
    
    string representation
  - stringToValue
```
public T stringToValue(java.lang.String txt)
                throws ConfigException
```
    Description copied from class: ConfigKey
    
    Decodes a string value to the value type of this key. An empty string should be interpreted as a null value, but this may cause an exception if null is not a permissible value for this key.
    
    Specified by:
    
    stringToValue in class ConfigKey<T>
    
    Parameters:
    
    txt - string representation of value
    
    Returns:
    
    value
    
    Throws:
    
    ConfigException
  - createSpecifier
```
public Specifier<T> createSpecifier()
```
    Description copied from class: ConfigKey
    
    Constructs a graphical control with which the user can specify a suitable value for association with this key.
    
    Specified by:
    
    createSpecifier in class ConfigKey<T>
    
    Returns:
    
    new specifier

Class ToggleNullConfigKey<T>

Constructor Summary

Method Summary

Methods inherited from class uk.ac.starlink.ttools.plot2.config.ConfigKey

Methods inherited from class java.lang.Object

Constructor Detail

ToggleNullConfigKey

Method Detail

valueToString

stringToValue

createSpecifier