Parameter (SciJava Javadocs 0-SNAPSHOT API)

```
@Retention(value=RUNTIME)
 @Target(value=FIELD)
public @interface Parameter
```
An annotation for indicating a field is an input or output parameter. This annotation is a useful way for plugins to declare their inputs and outputs simply.

Author:

Johannes Schindelin, Grant Harris, Curtis Rueden

Optional Element Summary

Optional Elements
Modifier and Type	Optional Element and Description
`Attr[]`	`attrs` A list of additional attributes which can be used to extend this annotation beyond its built-in capabilities.
`boolean`	`autoFill` Defines whether the parameter value should be filled programmatically, if possible.
`String`	`callback` Defines a function that is called whenever this parameter changes.
`String[]`	`choices` Defines the list of possible values (multiple choice text fields only).
`int`	`columns` Deprecated. Replaced by `style()`.
`String`	`description` Defines a description for the parameter.
`String`	`initializer` Defines a function that is called to initialize the parameter.
`String`	`label` Defines a label for the parameter.
`String`	`max` Defines the maximum allowed value (numeric parameters only).
`String`	`min` Defines the minimum allowed value (numeric parameters only).
`boolean`	`persist` Defines whether to remember the most recent value of the parameter.
`String`	`persistKey` Defines a key to use for saving the value persistently.
`boolean`	`required` Defines whether the parameter value must be non-null.
`String`	`stepSize` Defines the step size to use (numeric parameters only).
`String`	`style` Defines the preferred widget style.
`ItemIO`	`type` Defines the input/output type of the parameter.
`String`	`validater` Defines a function that is called to validate the parameter value after it is marked as resolved.
`ItemVisibility`	`visibility` Defines the "visibility" of the parameter.

- Element Detail
  - label
```
public abstract String label
```
    Defines a label for the parameter.
    
    Default:
    
    ""
- - description
```
public abstract String description
```
    Defines a description for the parameter.
    
    Default:
    
    ""
- - type
```
public abstract ItemIO type
```
    Defines the input/output type of the parameter.
    Choices are:
    - INPUT: parameter is an input for the plugin.
    - OUTPUT: parameter is an output for the plugin.
    - BOTH: parameter is both and input and an output for the plugin. This type is used to indicate an object that is mutated somehow during execution.
    Default:
    
    org.scijava.ItemIO.INPUT
- - visibility
```
public abstract ItemVisibility visibility
```
    Defines the "visibility" of the parameter.
    Choices are:
    - NORMAL: parameter is included in the history for purposes of data provenance, and included as a parameter when recording scripts.
    - TRANSIENT: parameter is excluded from the history for the purposes of data provenance, but still included as a parameter when recording scripts.
    - INVISIBLE: parameter is excluded from the history for the purposes of data provenance, and also excluded as a parameter when recording scripts. This option should only be used for parameters with no effect on the final output, such as a "verbose" flag.
    - MESSAGE: parameter value is intended as a message only, not editable by the user nor included as an input or output parameter.
    Default:
    
    org.scijava.ItemVisibility.NORMAL
- - autoFill
```
public abstract boolean autoFill
```
    Defines whether the parameter value should be filled programmatically, if possible.
    
    Default:
    
    true
- - required
```
public abstract boolean required
```
    Defines whether the parameter value must be non-null.
    
    Default:
    
    true
- - persist
```
public abstract boolean persist
```
    Defines whether to remember the most recent value of the parameter.
    
    Default:
    
    true
- - persistKey
```
public abstract String persistKey
```
    Defines a key to use for saving the value persistently.
    
    Default:
    
    ""
- - initializer
```
public abstract String initializer
```
    Defines a function that is called to initialize the parameter.
    
    Default:
    
    ""
- - validater
```
public abstract String validater
```
    Defines a function that is called to validate the parameter value after it is marked as resolved.
    
    See Also:
    
    Module.resolveInput(String)
    
    Default:
    
    ""
- - callback
```
public abstract String callback
```
    Defines a function that is called whenever this parameter changes.
    This mechanism enables interdependent parameters of various types. For example, two int parameters "width" and "height" could update each other when another boolean "Preserve aspect ratio" flag is set.
    
    Default:
    
    ""
- - style
```
public abstract String style
```
    Defines the preferred widget style.
    We do not use an enum because the styles need to be extensible. And we cannot use an interface-driven extensible enum pattern, because interfaces cannot be used as attributes within a Java annotation interface. So we fall back to strings!
    
    Default:
    
    ""
- - min
```
public abstract String min
```
    Defines the minimum allowed value (numeric parameters only).
    
    Default:
    
    ""
- - max
```
public abstract String max
```
    Defines the maximum allowed value (numeric parameters only).
    
    Default:
    
    ""
- - stepSize
```
public abstract String stepSize
```
    Defines the step size to use (numeric parameters only).
    
    Default:
    
    ""
- - choices
```
public abstract String[] choices
```
    Defines the list of possible values (multiple choice text fields only).
    
    Default:
    
    {}
- - attrs
```
public abstract Attr[] attrs
```
    A list of additional attributes which can be used to extend this annotation beyond its built-in capabilities.
    
    Default:
    
    {}
- - columns
```
@Deprecated
public abstract int columns
```
    Deprecated. Replaced by style().
    
    Default:
    
    6

Annotation Type Parameter

Optional Element Summary

Element Detail

label

description

type

visibility

autoFill

required

persist

persistKey

initializer

validater

callback

style

min

max

stepSize

choices

attrs

columns