org.geotools.feature.visitor

Enum Aggregate

Object

Enum<Aggregate>

Aggregate

All Implemented Interfaces:

Serializable, Comparable<Aggregate>

public enum Aggregate
extends Enum<Aggregate>

Aggregate functions defined for use with the GeoTools library.

Aggregates are backed by a FeatureCalc visitor for direct use with a FeatureCollection (or use with GroupByVisitor ). THe create(Expression) method is used as a factory method to configure an appropriate visitor.

During processing a CalcResult is used to store intermediate results. Implementations that handle an aggregate function directly (such as JDBCDataStore) can use can use the wrap method to generate the expect CalcResult from a calculated raw value.

Enum Constant Summary

Enum Constants

Enum Constant and Description
AVERAGE
COUNT
MAX
MEDIAN
MIN
STD_DEV
SUM
SUMAREA

Method Summary

Modifier and Type	Method and Description
abstract FeatureCalc	create(Expression expression) Factory method creating a visitor using an aggregate attribute.
static Aggregate	valueOf(String name) Returns the enum constant of this type with the specified name.
static Aggregate	valueOfIgnoreCase(String visitorName) Helper method that given a visitor name returns the appropriate enum constant.
static Aggregate[]	values() Returns an array containing the constants of this enum type, in the order they are declared.
abstract CalcResult	wrap(Expression expression, Object value) Wraps a raw value in the appropriate visitor calculation result.

Methods inherited from class Enum

clone, compareTo, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

Methods inherited from class Object

getClass, notify, notifyAll, wait, wait, wait

Enum Constant Detail

AVERAGE

public static final Aggregate AVERAGE

COUNT

public static final Aggregate COUNT

MAX

public static final Aggregate MAX

MEDIAN

public static final Aggregate MEDIAN

MIN

public static final Aggregate MIN

STD_DEV

public static final Aggregate STD_DEV

SUM

public static final Aggregate SUM

SUMAREA

public static final Aggregate SUMAREA

Method Detail

values

public static Aggregate[] values()

Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows:

for (Aggregate c : Aggregate.values())
    System.out.println(c);

Returns:

an array containing the constants of this enum type, in the order they are declared

valueOf

public static Aggregate valueOf(String name)

Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)

Parameters:

name - the name of the enum constant to be returned.

Returns:

the enum constant with the specified name

Throws:

IllegalArgumentException - if this enum type has no constant with the specified name

NullPointerException - if the argument is null

create

public abstract FeatureCalc create(Expression expression)

Factory method creating a visitor using an aggregate attribute.

Parameters:

expression - Expression used to sample collection (often a PropertyName)

Returns:

a new instance of the visitor

wrap

public abstract CalcResult wrap(Expression expression,
                                Object value)

Wraps a raw value in the appropriate visitor calculation result. The typical usage of this is to wrap values returned by stores able to handle the visitor (for example the JDBCDataStore).

Parameters:

expression - Expression used to sample collection (often a PropertyName)

value - The raw value to be wrapped

Returns:

value Wrapped in the appropriate visitor calculation result

valueOfIgnoreCase

public static Aggregate valueOfIgnoreCase(String visitorName)

Helper method that given a visitor name returns the appropriate enum constant.

The performed match by name is more permissive that the default one. The match will not be case sensitive and slightly different names can be used (camel case versus snake case).

Parameters:

visitorName - the visitor name

Returns:

this enum constant that machs the visitor name