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Oracle® Fusion Middleware Java API Reference for Oracle Coherence 12c (12.1.3.0.0) E47890-01 |
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java.lang.Object
com.tangosol.util.Base
com.tangosol.util.BitHelper
com.tangosol.util.ExternalizableHelper
com.tangosol.util.aggregator.AbstractAggregator
com.tangosol.util.aggregator.DistinctValues
public class DistinctValues
Return the set of unique values extracted from a set of entries in a Map. If the set of entries is empty, an empty set is returned.
This aggregator could be used in combination with MultiExtractor
allowing to collect all unique combinations (tuples) of a given set of attributes.
The DistinctValues aggregator covers a simple case of a more generic aggregation pattern implemented by the GroupAggregator
, which in addition to collecting all distinct values or tuples, runs an aggregation against each distinct entry set (group).
Nested Class Summary |
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Nested classes/interfaces inherited from interface com.tangosol.util.InvocableMap.ParallelAwareAggregator |
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InvocableMap.ParallelAwareAggregator.PartialResultAggregator |
Field Summary | |
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protected java.util.Set |
m_set The resulting set of distinct values. |
Fields inherited from class com.tangosol.util.aggregator.AbstractAggregator |
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m_fParallel |
Constructor Summary | |
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DistinctValues() Default constructor (necessary for the ExternalizableLite interface). |
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DistinctValues(java.lang.String sMethod) Construct an DistinctValues aggregator. |
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DistinctValues(ValueExtractor extractor) Construct a DistinctValues aggregator. |
Method Summary | |
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protected java.util.Set |
ensureSet() Return a set that can be used to store distinct values, creating it if one has not already been created. |
protected java.lang.Object |
finalizeResult(boolean fFinal) Obtain the result of the aggregation. |
protected void |
init(boolean fFinal) Initialize the aggregation result. |
protected void |
process(java.lang.Object o, boolean fFinal) Incorporate one aggregatable value into the result. |
Methods inherited from class com.tangosol.util.aggregator.AbstractAggregator |
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aggregate, aggregateResults, equals, getParallelAggregator, getValueExtractor, hashCode, processEntry, readExternal, readExternal, toString, writeExternal, writeExternal |
Methods inherited from class com.tangosol.util.BitHelper |
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countBits, countBits, countBits, indexOfLSB, indexOfLSB, indexOfLSB, indexOfMSB, indexOfMSB, indexOfMSB, rotateLeft, rotateLeft, rotateLeft, rotateRight, rotateRight, rotateRight, toBitString, toBitString, toBitString, toBytes, toBytes, toBytes, toBytes, toInt, toInt, toLong, toLong |
Field Detail |
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protected transient java.util.Set m_set
Constructor Detail |
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public DistinctValues()
public DistinctValues(ValueExtractor extractor)
extractor
- the extractor that provides a value in the form of any Java objectpublic DistinctValues(java.lang.String sMethod)
sMethod
- the name of the method that returns a value in the form of any Java objectMethod Detail |
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protected void init(boolean fFinal)
init
in class AbstractAggregator
fFinal
- true is passed if the aggregation process that is being initialized must produce a final aggregation result; this will only be false if a parallel approach is being used and the initial (partial) aggregation process is being initializedprotected void process(java.lang.Object o, boolean fFinal)
If the fFinal parameter is true, the given object is a partial result (returned by an individual parallel aggregator) that should be incorporated into the final result; otherwise, the object is a value extracted from an InvocableMap.Entry
.
process
in class AbstractAggregator
o
- the value to incorporate into the aggregated resultfFinal
- true to indicate that the given object is a partial result returned by a parallel aggregatorprotected java.lang.Object finalizeResult(boolean fFinal)
If the fFinal parameter is true, the returned object must be the final result of the aggregation; otherwise, the returned object will be treated as a partial result that should be incorporated into the final result.
finalizeResult
in class AbstractAggregator
fFinal
- true to indicate that the final result of the aggregation process should be returned; this will only be false if a parallel approach is being usedprotected java.util.Set ensureSet()
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Oracle® Fusion Middleware Java API Reference for Oracle Coherence 12c (12.1.3.0.0) E47890-01 |
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