weka.core

## Class Attribute

- java.lang.Object
- - weka.core.Attribute

- All Implemented Interfaces:
    java.io.Serializable, Copyable, RevisionHandler

      public class Attribute
      extends java.lang.Object
      implements Copyable, java.io.Serializable, RevisionHandler

  Class for handling an attribute. Once an attribute has been created, it can't be changed.

  The following attribute types are supported:

  - numeric:
    This type of attribute represents a floating-point number.
  - nominal:
    This type of attribute represents a fixed set of nominal values.
  - string:
    This type of attribute represents a dynamically expanding set of nominal values. Usually used in text classification.
  - date:
    This type of attribute represents a date, internally represented as floating-point number storing the milliseconds since January 1, 1970, 00:00:00 GMT. The string representation of the date must be ISO-8601 compliant, the default is `yyyy-MM-dd'T'HH:mm:ss`.
  - relational:
    This type of attribute can contain other attributes and is, e.g., used for representing Multi-Instance data. (Multi-Instance data consists of a nominal attribute containing the bag-id, then a relational attribute with all the attributes of the bag, and finally the class attribute.)
  Typical usage (code from the main() method of this class):

  `...
  // Create numeric attributes "length" and "weight"
  Attribute length = new Attribute("length");
  Attribute weight = new Attribute("weight");
  // Create list to hold nominal values "first", "second", "third"
  List my_nominal_values = new ArrayList(3);
  my_nominal_values.add("first");
  my_nominal_values.add("second");
  my_nominal_values.add("third");
  // Create nominal attribute "position"
  Attribute position = new Attribute("position", my_nominal_values);
  ...
  `

  Version:
    $Revision: 12593 $
  Author:
    Eibe Frank (eibe@cs.waikato.ac.nz)
  See Also:
    Serialized Form

- - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `static java.lang.String` | `ARFF_ATTRIBUTE` The keyword used to denote the start of an arff attribute declaration
    `static java.lang.String` | `ARFF_ATTRIBUTE_DATE` The keyword used to denote a date attribute
    `static java.lang.String` | `ARFF_ATTRIBUTE_INTEGER` A keyword used to denote a numeric attribute
    `static java.lang.String` | `ARFF_ATTRIBUTE_NUMERIC` A keyword used to denote a numeric attribute
    `static java.lang.String` | `ARFF_ATTRIBUTE_REAL` A keyword used to denote a numeric attribute
    `static java.lang.String` | `ARFF_ATTRIBUTE_RELATIONAL` The keyword used to denote a relation-valued attribute
    `static java.lang.String` | `ARFF_ATTRIBUTE_STRING` The keyword used to denote a string attribute
    `static java.lang.String` | `ARFF_END_SUBRELATION` The keyword used to denote the end of the declaration of a subrelation
    `static int` | `DATE` Constant set for attributes with date values.
    `static int` | `NOMINAL` Constant set for nominal attributes.
    `static int` | `NUMERIC` Constant set for numeric attributes.
    `static int` | `ORDERING_MODULO` Constant set for modulo-ordered attributes.
    `static int` | `ORDERING_ORDERED` Constant set for ordered attributes.
    `static int` | `ORDERING_SYMBOLIC` Constant set for symbolic attributes.
    `static int` | `RELATIONAL` Constant set for relation-valued attributes.
    `static int` | `STRING` Constant set for attributes with string values.

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `Attribute(java.lang.String attributeName)` Constructor for a numeric attribute.
    `Attribute(java.lang.String attributeName, Instances header)` Constructor for relation-valued attributes.
    `Attribute(java.lang.String attributeName, Instances header, int index)` Constructor for a relation-valued attribute with a particular index.
    `Attribute(java.lang.String attributeName, Instances header, ProtectedProperties metadata)` Constructor for relation-valued attributes.
    `Attribute(java.lang.String attributeName, int index)` Constructor for a numeric attribute with a particular index.
    `Attribute(java.lang.String attributeName, java.util.List<java.lang.String> attributeValues)` Constructor for nominal attributes and string attributes.
    `Attribute(java.lang.String attributeName, java.util.List<java.lang.String> attributeValues, int index)` Constructor for nominal attributes and string attributes with a particular index.
    `Attribute(java.lang.String attributeName, java.util.List<java.lang.String> attributeValues, ProtectedProperties metadata)` Constructor for nominal attributes and string attributes, where metadata is supplied.
    `Attribute(java.lang.String attributeName, ProtectedProperties metadata)` Constructor for a numeric attribute, where metadata is supplied.
    `Attribute(java.lang.String attributeName, java.lang.String dateFormat)` Constructor for a date attribute.
    `Attribute(java.lang.String attributeName, java.lang.String dateFormat, int index)` Constructor for date attributes with a particular index.
    `Attribute(java.lang.String attributeName, java.lang.String dateFormat, ProtectedProperties metadata)` Constructor for a date attribute, where metadata is supplied.

  - ### Method Summary

    All Methods Static Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `int` | `addRelation(Instances value)` Adds a relation to a relation-valued attribute.
    `int` | `addStringValue(Attribute src, int index)` Adds a string value to the list of valid strings for attributes of type STRING and returns the index of the string.
    `int` | `addStringValue(java.lang.String value)` Adds a string value to the list of valid strings for attributes of type STRING and returns the index of the string.
    `java.lang.Object` | `copy()` Produces a shallow copy of this attribute.
    `Attribute` | `copy(java.lang.String newName)` Produces a shallow copy of this attribute with a new name.
    `java.util.Enumeration<java.lang.Object>` | `enumerateValues()` Returns an enumeration of all the attribute's values if the attribute is nominal, string, or relation-valued, null otherwise.
    `boolean` | `equals(java.lang.Object other)` Tests if given attribute is equal to this attribute.
    `java.lang.String` | `equalsMsg(java.lang.Object other)` Tests if given attribute is equal to this attribute.
    `java.lang.String` | `formatDate(double date)` Returns the given amount of milliseconds formatted according to the current Date format.
    `java.lang.String` | `getDateFormat()` Returns the Date format pattern in case this attribute is of type DATE, otherwise an empty string.
    `double` | `getLowerNumericBound()` Returns the lower bound of a numeric attribute.
    `ProtectedProperties` | `getMetadata()` Returns the properties supplied for this attribute.
    `java.lang.String` | `getRevision()` Returns the revision string.
    `double` | `getUpperNumericBound()` Returns the upper bound of a numeric attribute.
    `int` | `hashCode()` Returns a hash code for this attribute based on its name.
    `boolean` | `hasZeropoint()` Returns whether the attribute has a zeropoint and may be added meaningfully.
    `int` | `index()` Returns the index of this attribute.
    `int` | `indexOfValue(java.lang.String value)` Returns the index of a given attribute value.
    `boolean` | `isAveragable()` Returns whether the attribute can be averaged meaningfully.
    `boolean` | `isDate()` Tests if the attribute is a date type.
    `boolean` | `isInRange(double value)` Determines whether a value lies within the bounds of the attribute.
    `boolean` | `isNominal()` Test if the attribute is nominal.
    `boolean` | `isNumeric()` Tests if the attribute is numeric.
    `boolean` | `isRegular()` Returns whether the attribute values are equally spaced.
    `boolean` | `isRelationValued()` Tests if the attribute is relation valued.
    `boolean` | `isString()` Tests if the attribute is a string.
    `boolean` | `lowerNumericBoundIsOpen()` Returns whether the lower numeric bound of the attribute is open.
    `static void` | `main(java.lang.String[] ops)` Simple main method for testing this class.
    `java.lang.String` | `name()` Returns the attribute's name.
    `int` | `numValues()` Returns the number of attribute values.
    `int` | `ordering()` Returns the ordering of the attribute.
    `double` | `parseDate(java.lang.String string)` Parses the given String as Date, according to the current format and returns the corresponding amount of milliseconds.
    `Instances` | `relation()` Returns the header info for a relation-valued attribute, null if the attribute is not relation-valued.
    `Instances` | `relation(int valIndex)` Returns a value of a relation-valued attribute.
    `void` | `setStringValue(java.lang.String value)` Clear the map and list of values and set them to contain just the supplied value
    `void` | `setWeight(double value)` Sets the new attribute's weight.
    `java.lang.String` | `toString()` Returns a description of this attribute in ARFF format.
    `int` | `type()` Returns the attribute's type as an integer.
    `static java.lang.String` | `typeToString(Attribute att)` Returns a string representation of the attribute type.
    `static java.lang.String` | `typeToString(int type)` Returns a string representation of the attribute type.
    `static java.lang.String` | `typeToStringShort(Attribute att)` Returns a short string representation of the attribute type.
    `static java.lang.String` | `typeToStringShort(int type)` Returns a short string representation of the attribute type.
    `boolean` | `upperNumericBoundIsOpen()` Returns whether the upper numeric bound of the attribute is open.
    `java.lang.String` | `value(int valIndex)` Returns a value of a nominal or string attribute.
    `double` | `weight()` Returns the attribute's weight.

    - ### Methods inherited from class java.lang.Object

      `getClass, notify, notifyAll, wait, wait, wait`

- - ### Field Detail

    - #### NUMERIC

          public static final int NUMERIC

      Constant set for numeric attributes.
      See Also:
        Constant Field Values

    - #### NOMINAL

          public static final int NOMINAL

      Constant set for nominal attributes.
      See Also:
        Constant Field Values

    - #### STRING

          public static final int STRING

      Constant set for attributes with string values.
      See Also:
        Constant Field Values

    - #### DATE

          public static final int DATE

      Constant set for attributes with date values.
      See Also:
        Constant Field Values

    - #### RELATIONAL

          public static final int RELATIONAL

      Constant set for relation-valued attributes.
      See Also:
        Constant Field Values

    - #### ORDERING_SYMBOLIC

          public static final int ORDERING_SYMBOLIC

      Constant set for symbolic attributes.
      See Also:
        Constant Field Values

    - #### ORDERING_ORDERED

          public static final int ORDERING_ORDERED

      Constant set for ordered attributes.
      See Also:
        Constant Field Values

    - #### ORDERING_MODULO

          public static final int ORDERING_MODULO

      Constant set for modulo-ordered attributes.
      See Also:
        Constant Field Values

    - #### ARFF_ATTRIBUTE

          public static final java.lang.String ARFF_ATTRIBUTE

      The keyword used to denote the start of an arff attribute declaration
      See Also:
        Constant Field Values

    - #### ARFF_ATTRIBUTE_INTEGER

          public static final java.lang.String ARFF_ATTRIBUTE_INTEGER

      A keyword used to denote a numeric attribute
      See Also:
        Constant Field Values

    - #### ARFF_ATTRIBUTE_REAL

          public static final java.lang.String ARFF_ATTRIBUTE_REAL

      A keyword used to denote a numeric attribute
      See Also:
        Constant Field Values

    - #### ARFF_ATTRIBUTE_NUMERIC

          public static final java.lang.String ARFF_ATTRIBUTE_NUMERIC

      A keyword used to denote a numeric attribute
      See Also:
        Constant Field Values

    - #### ARFF_ATTRIBUTE_STRING

          public static final java.lang.String ARFF_ATTRIBUTE_STRING

      The keyword used to denote a string attribute
      See Also:
        Constant Field Values

    - #### ARFF_ATTRIBUTE_DATE

          public static final java.lang.String ARFF_ATTRIBUTE_DATE

      The keyword used to denote a date attribute
      See Also:
        Constant Field Values

    - #### ARFF_ATTRIBUTE_RELATIONAL

          public static final java.lang.String ARFF_ATTRIBUTE_RELATIONAL

      The keyword used to denote a relation-valued attribute
      See Also:
        Constant Field Values

    - #### ARFF_END_SUBRELATION

          public static final java.lang.String ARFF_END_SUBRELATION

      The keyword used to denote the end of the declaration of a subrelation
      See Also:
        Constant Field Values

  - ### Constructor Detail

    - #### Attribute

          public Attribute(java.lang.String attributeName)

      Constructor for a numeric attribute.
      Parameters:
        `attributeName` - the name for the attribute

    - #### Attribute

          public Attribute(java.lang.String attributeName,
                           ProtectedProperties metadata)

      Constructor for a numeric attribute, where metadata is supplied.
      Parameters:
        `attributeName` - the name for the attribute
        `metadata` - the attribute's properties

    - #### Attribute

          public Attribute(java.lang.String attributeName,
                           java.lang.String dateFormat)

      Constructor for a date attribute.
      Parameters:
        `attributeName` - the name for the attribute
        `dateFormat` - a string suitable for use with SimpleDateFormatter for parsing dates.

    - #### Attribute

          public Attribute(java.lang.String attributeName,
                           java.lang.String dateFormat,
                           ProtectedProperties metadata)

      Constructor for a date attribute, where metadata is supplied.
      Parameters:
        `attributeName` - the name for the attribute
        `dateFormat` - a string suitable for use with SimpleDateFormatter for parsing dates.
        `metadata` - the attribute's properties

    - #### Attribute

          public Attribute(java.lang.String attributeName,
                           java.util.List<java.lang.String> attributeValues)

      Constructor for nominal attributes and string attributes. If a null vector of attribute values is passed to the method, the attribute is assumed to be a string.
      Parameters:
        `attributeName` - the name for the attribute
        `attributeValues` - a vector of strings denoting the attribute values. Null if the attribute is a string attribute.

    - #### Attribute

          public Attribute(java.lang.String attributeName,
                           java.util.List<java.lang.String> attributeValues,
                           ProtectedProperties metadata)

      Constructor for nominal attributes and string attributes, where metadata is supplied. If a null vector of attribute values is passed to the method, the attribute is assumed to be a string.
      Parameters:
        `attributeName` - the name for the attribute
        `attributeValues` - a vector of strings denoting the attribute values. Null if the attribute is a string attribute.
        `metadata` - the attribute's properties

    - #### Attribute

          public Attribute(java.lang.String attributeName,
                           Instances header)

      Constructor for relation-valued attributes.
      Parameters:
        `attributeName` - the name for the attribute
        `header` - an Instances object specifying the header of the relation.

    - #### Attribute

          public Attribute(java.lang.String attributeName,
                           Instances header,
                           ProtectedProperties metadata)

      Constructor for relation-valued attributes.
      Parameters:
        `attributeName` - the name for the attribute
        `header` - an Instances object specifying the header of the relation.
        `metadata` - the attribute's properties

    - #### Attribute

          public Attribute(java.lang.String attributeName,
                           int index)

      Constructor for a numeric attribute with a particular index.
      Parameters:
        `attributeName` - the name for the attribute
        `index` - the attribute's index

    - #### Attribute

          public Attribute(java.lang.String attributeName,
                           java.lang.String dateFormat,
                           int index)

      Constructor for date attributes with a particular index.
      Parameters:
        `attributeName` - the name for the attribute
        `dateFormat` - a string suitable for use with SimpleDateFormatter for parsing dates. Null for a default format string.
        `index` - the attribute's index

    - #### Attribute

          public Attribute(java.lang.String attributeName,
                           java.util.List<java.lang.String> attributeValues,
                           int index)

      Constructor for nominal attributes and string attributes with a particular index. If a null vector of attribute values is passed to the method, the attribute is assumed to be a string.
      Parameters:
        `attributeName` - the name for the attribute
        `attributeValues` - a vector of strings denoting the attribute values. Null if the attribute is a string attribute.
        `index` - the attribute's index

    - #### Attribute

          public Attribute(java.lang.String attributeName,
                           Instances header,
                           int index)

      Constructor for a relation-valued attribute with a particular index.
      Parameters:
        `attributeName` - the name for the attribute
        `header` - the header information for this attribute
        `index` - the attribute's index

  - ### Method Detail

    - #### copy

          public java.lang.Object copy()

      Produces a shallow copy of this attribute.
      Specified by:
        `copy` in interface `Copyable`
      Returns:
        a copy of this attribute with the same index

    - #### enumerateValues

          public final java.util.Enumeration<java.lang.Object> enumerateValues()

      Returns an enumeration of all the attribute's values if the attribute is nominal, string, or relation-valued, null otherwise.
      Returns:
        enumeration of all the attribute's values

    - #### equals

          public final boolean equals(java.lang.Object other)

      Tests if given attribute is equal to this attribute. Attribute indices are ignored in the comparison.
      Overrides:
        `equals` in class `java.lang.Object`
      Parameters:
        `other` - the Object to be compared to this attribute
      Returns:
        true if the given attribute is equal to this attribute

    - #### hashCode

          public final int hashCode()

      Returns a hash code for this attribute based on its name.
      Overrides:
        `hashCode` in class `java.lang.Object`
      Returns:
        the hash code

    - #### equalsMsg

          public final java.lang.String equalsMsg(java.lang.Object other)

      Tests if given attribute is equal to this attribute. If they're not the same a message detailing why they differ will be returned, otherwise null. Attribute indices are ignored in the comparison.
      Parameters:
        `other` - the Object to be compared to this attribute
      Returns:
        null if the given attribute is equal to this attribute

    - #### typeToString

          public static java.lang.String typeToString(Attribute att)

      Returns a string representation of the attribute type.
      Parameters:
        `att` - the attribute to return the type string for
      Returns:
        the string representation of the attribute type

    - #### typeToString

          public static java.lang.String typeToString(int type)

      Returns a string representation of the attribute type.
      Parameters:
        `type` - the type of the attribute
      Returns:
        the string representation of the attribute type

    - #### typeToStringShort

          public static java.lang.String typeToStringShort(Attribute att)

      Returns a short string representation of the attribute type.
      Parameters:
        `att` - the attribute to return the type string for
      Returns:
        the string representation of the attribute type

    - #### typeToStringShort

          public static java.lang.String typeToStringShort(int type)

      Returns a short string representation of the attribute type.
      Parameters:
        `type` - the type of the attribute
      Returns:
        the string representation of the attribute type

    - #### index

          public final int index()

      Returns the index of this attribute.
      Returns:
        the index of this attribute

    - #### indexOfValue

          public final int indexOfValue(java.lang.String value)

      Returns the index of a given attribute value. (The index of the first occurence of this value.)
      Parameters:
        `value` - the value for which the index is to be returned
      Returns:
        the index of the given attribute value if attribute is nominal or a string, -1 if it is not or the value can't be found

    - #### isNominal

          public final boolean isNominal()

      Test if the attribute is nominal.
      Returns:
        true if the attribute is nominal

    - #### isNumeric

          public final boolean isNumeric()

      Tests if the attribute is numeric.
      Returns:
        true if the attribute is numeric

    - #### isRelationValued

          public final boolean isRelationValued()

      Tests if the attribute is relation valued.
      Returns:
        true if the attribute is relation valued

    - #### isString

          public final boolean isString()

      Tests if the attribute is a string.
      Returns:
        true if the attribute is a string

    - #### isDate

          public final boolean isDate()

      Tests if the attribute is a date type.
      Returns:
        true if the attribute is a date type

    - #### name

          public final java.lang.String name()

      Returns the attribute's name.
      Returns:
        the attribute's name as a string

    - #### numValues

          public final int numValues()

      Returns the number of attribute values. Returns 0 for attributes that are not either nominal, string, or relation-valued.
      Returns:
        the number of attribute values

    - #### toString

          public final java.lang.String toString()

      Returns a description of this attribute in ARFF format. Quotes strings if they contain whitespace characters, or if they are a question mark.
      Overrides:
        `toString` in class `java.lang.Object`
      Returns:
        a description of this attribute as a string

    - #### type

          public final int type()

      Returns the attribute's type as an integer.
      Returns:
        the attribute's type.

    - #### getDateFormat

          public final java.lang.String getDateFormat()

      Returns the Date format pattern in case this attribute is of type DATE, otherwise an empty string.
      Returns:
        the date format pattern
      See Also:
        `SimpleDateFormat`

    - #### value

          public final java.lang.String value(int valIndex)

      Returns a value of a nominal or string attribute. Returns an empty string if the attribute is neither a string nor a nominal attribute.
      Parameters:
        `valIndex` - the value's index
      Returns:
        the attribute's value as a string

    - #### relation

          public final Instances relation()

      Returns the header info for a relation-valued attribute, null if the attribute is not relation-valued.
      Returns:
        the attribute's value as an Instances object

    - #### relation

          public final Instances relation(int valIndex)

      Returns a value of a relation-valued attribute. Returns null if the attribute is not relation-valued.
      Parameters:
        `valIndex` - the value's index
      Returns:
        the attribute's value as an Instances object

    - #### addStringValue

          public int addStringValue(java.lang.String value)

      Adds a string value to the list of valid strings for attributes of type STRING and returns the index of the string.
      Parameters:
        `value` - The string value to add
      Returns:
        the index assigned to the string, or -1 if the attribute is not of type Attribute.STRING

    - #### setStringValue

          public void setStringValue(java.lang.String value)

      Clear the map and list of values and set them to contain just the supplied value
      Parameters:
        `value` - the current (and only) value of this String attribute. If null then just the map is cleared.

    - #### addStringValue

          public int addStringValue(Attribute src,
                                    int index)

      Adds a string value to the list of valid strings for attributes of type STRING and returns the index of the string. This method is more efficient than addStringValue(String) for long strings.
      Parameters:
        `src` - The Attribute containing the string value to add.
        `index` - the index of the string value in the source attribute.
      Returns:
        the index assigned to the string, or -1 if the attribute is not of type Attribute.STRING

    - #### addRelation

          public int addRelation(Instances value)

      Adds a relation to a relation-valued attribute.
      Parameters:
        `value` - The value to add
      Returns:
        the index assigned to the value, or -1 if the attribute is not of type Attribute.RELATIONAL

    - #### copy

          public final Attribute copy(java.lang.String newName)

      Produces a shallow copy of this attribute with a new name.
      Parameters:
        `newName` - the name of the new attribute
      Returns:
        a copy of this attribute with the same index

    - #### formatDate

          public java.lang.String formatDate(double date)

      Returns the given amount of milliseconds formatted according to the current Date format.
      Parameters:
        `date` - the date, represented in milliseconds since January 1, 1970, 00:00:00 GMT, to return as string
      Returns:
        the formatted date

    - #### parseDate

          public double parseDate(java.lang.String string)
                           throws java.text.ParseException

      Parses the given String as Date, according to the current format and returns the corresponding amount of milliseconds.
      Parameters:
        `string` - the date to parse
      Returns:
        the date in milliseconds since January 1, 1970, 00:00:00 GMT
      Throws:
        `java.text.ParseException` - if parsing fails

    - #### getMetadata

          public final ProtectedProperties getMetadata()

      Returns the properties supplied for this attribute. Returns null if there is no meta data for this attribute.
      Returns:
        metadata for this attribute

    - #### ordering

          public final int ordering()

      Returns the ordering of the attribute. One of the following: ORDERING_SYMBOLIC - attribute values should be treated as symbols. ORDERING_ORDERED - attribute values have a global ordering. ORDERING_MODULO - attribute values have an ordering which wraps.
      Returns:
        the ordering type of the attribute

    - #### isRegular

          public final boolean isRegular()

      Returns whether the attribute values are equally spaced.
      Returns:
        whether the attribute is regular or not

    - #### isAveragable

          public final boolean isAveragable()

      Returns whether the attribute can be averaged meaningfully.
      Returns:
        whether the attribute can be averaged or not

    - #### hasZeropoint

          public final boolean hasZeropoint()

      Returns whether the attribute has a zeropoint and may be added meaningfully.
      Returns:
        whether the attribute has a zeropoint or not

    - #### weight

          public final double weight()

      Returns the attribute's weight.
      Returns:
        the attribute's weight as a double

    - #### setWeight

          public void setWeight(double value)

      Sets the new attribute's weight. Does not modify the weight info stored in the attribute's meta data object!
      Parameters:
        `value` - the new weight

    - #### getLowerNumericBound

          public final double getLowerNumericBound()

      Returns the lower bound of a numeric attribute.
      Returns:
        the lower bound of the specified numeric range

    - #### lowerNumericBoundIsOpen

          public final boolean lowerNumericBoundIsOpen()

      Returns whether the lower numeric bound of the attribute is open.
      Returns:
        whether the lower numeric bound is open or not (closed)

    - #### getUpperNumericBound

          public final double getUpperNumericBound()

      Returns the upper bound of a numeric attribute.
      Returns:
        the upper bound of the specified numeric range

    - #### upperNumericBoundIsOpen

          public final boolean upperNumericBoundIsOpen()

      Returns whether the upper numeric bound of the attribute is open.
      Returns:
        whether the upper numeric bound is open or not (closed)

    - #### isInRange

          public final boolean isInRange(double value)

      Determines whether a value lies within the bounds of the attribute.
      Parameters:
        `value` - the value to check
      Returns:
        whether the value is in range

    - #### getRevision

          public java.lang.String getRevision()

      Returns the revision string.
      Specified by:
        `getRevision` in interface `RevisionHandler`
      Returns:
        the revision

    - #### main

          public static void main(java.lang.String[] ops)

      Simple main method for testing this class.
      Parameters:
        `ops` - the commandline options