net.sf.jagg
Class Aggregation

java.lang.Object
  net.sf.jagg.Aggregation

public class Aggregation
extends java.lang.Object

The Aggregation class performs the actual aggregation operations. It contains a Builder class that, following the Builder Pattern, builds a Aggregation object that can be used for the actual aggregation calculations.

Since:

0.7.0

Author:

Randy Gettman

Nested Class Summary

static class

Aggregation.Builder This Builder class follows the "Builder" pattern to create an Aggregation object.

Method Summary

<T> java.util.List<AggregateValue<T>>	groupBy(java.util.List<T> values) Perform one or more aggregate operations on a List<T>.
<T extends java.lang.Comparable<? super T>> java.util.List<AggregateValue<T>>	groupByComparable(java.util.List<T> values) Perform one or more aggregate operations on a List<T>.

Methods inherited from class java.lang.Object

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

Method Detail

groupByComparable

public <T extends java.lang.Comparable<? super T>> java.util.List<AggregateValue<T>> groupByComparable(java.util.List<T> values)

Perform one or more aggregate operations on a List<T>. T should have a "natural ordering", that is, it must be Comparable, and compareTo defines the properties with which to "group by" with its consideration of different properties to determine order. This sorts a copy of the list of values, based how the objects' compareTo method compares them.

Type Parameters:

T - The object type to aggregate, which must be Comparable.

Parameters:

values - The List<T> of objects to aggregate.

Returns:

A List<AggregateValue<T>>.

groupBy

public <T> java.util.List<AggregateValue<T>> groupBy(java.util.List<T> values)

Perform one or more aggregate operations on a List<T>. T does not need to be Comparable. This operates on a copy of the list of values, either sorted based on the "group by" properties (if any), or grouped into equivalence classes using multiset discrimination.

Type Parameters:

T - The object type to aggregate.

Parameters:

values - The List<T> of objects to aggregate.

Returns:

A List<AggregateValue<T>>.