org.apache.metamodel.query

Class DefaultAggregateFunction<T>

java.lang.Object

org.apache.metamodel.query.DefaultAggregateFunction<T>

All Implemented Interfaces:

Serializable, AggregateFunction, FunctionType

Direct Known Subclasses:

AverageAggregateFunction, CountAggregateFunction, FirstAggregateFunction, LastAggregateFunction, MaxAggregateFunction, MinAggregateFunction, RandomAggregateFunction, SumAggregateFunction

public abstract class DefaultAggregateFunction<T>
extends Object
implements AggregateFunction

Implementation of the AggregateFunction.

See Also:

Serialized Form

Field Summary

Fields inherited from interface org.apache.metamodel.query.FunctionType

AVG, COUNT, FIRST, JAVA_SUBSTRING, LAST, MAP_VALUE, MAX, MIN, RANDOM, SUBSTRING, SUM, TO_BOOLEAN, TO_DATE, TO_NUMBER, TO_STRING

Constructor Summary

Constructors

Constructor and Description
DefaultAggregateFunction()

Method Summary

Modifier and Type	Method and Description
Object	evaluate(Object... values) Executes the function
ColumnType	getExpectedColumnType(ColumnType type) Returns the function ColumnType.
String	toString()

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.metamodel.query.AggregateFunction

createAggregateBuilder

Methods inherited from interface org.apache.metamodel.query.FunctionType

getFunctionName

Constructor Detail

DefaultAggregateFunction

public DefaultAggregateFunction()

Method Detail

getExpectedColumnType

public ColumnType getExpectedColumnType(ColumnType type)

Description copied from interface: AggregateFunction

Returns the function ColumnType.

Specified by:

getExpectedColumnType in interface AggregateFunction

Specified by:

getExpectedColumnType in interface FunctionType

Returns:

the ColumnType

evaluate

public Object evaluate(Object... values)

Executes the function

Specified by:

evaluate in interface AggregateFunction

Parameters:

values - the values to be evaluated. If a value is null it won't be evaluated

Returns:

the result of the function execution. The return type class is dependent on the FunctionType and the values provided. COUNT yields a Long, AVG and SUM yields Double values and MAX and MIN yields the type of the provided values.

toString

public String toString()

Overrides:

toString in class Object