Class Count<T>
- java.lang.Object
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- org.apache.storm.streams.operations.aggregators.Count<T>
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- Type Parameters:
T- the value type
- All Implemented Interfaces:
Serializable,CombinerAggregator<T,Long,Long>,Operation
public class Count<T> extends Object implements CombinerAggregator<T,Long,Long>
Computes the count of values.- See Also:
- Serialized Form
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Constructor Summary
Constructors Constructor Description Count()
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description Longapply(Long accum, T value)Updates the accumulator by applying the current accumulator with the value.Longinit()The initial value of the accumulator to start with.Longmerge(Long accum1, Long accum2)Merges two accumulators and returns the merged accumulator.Longresult(Long accum)Produces a result value out of the accumulator.
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Method Detail
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init
public Long init()
Description copied from interface:CombinerAggregatorThe initial value of the accumulator to start with.- Specified by:
initin interfaceCombinerAggregator<T,Long,Long>- Returns:
- the initial value of the accumulator
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apply
public Long apply(Long accum, T value)
Description copied from interface:CombinerAggregatorUpdates the accumulator by applying the current accumulator with the value.- Specified by:
applyin interfaceCombinerAggregator<T,Long,Long>- Parameters:
accum- the current accumulatorvalue- the value- Returns:
- the updated accumulator
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merge
public Long merge(Long accum1, Long accum2)
Description copied from interface:CombinerAggregatorMerges two accumulators and returns the merged accumulator.- Specified by:
mergein interfaceCombinerAggregator<T,Long,Long>- Parameters:
accum1- the first accumulatoraccum2- the second accumulator- Returns:
- the merged accumulator
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result
public Long result(Long accum)
Description copied from interface:CombinerAggregatorProduces a result value out of the accumulator.- Specified by:
resultin interfaceCombinerAggregator<T,Long,Long>- Parameters:
accum- the accumulator- Returns:
- the result
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