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Class JBMSTours.aggregates.MaxButOneIntegerAggregator
java.lang.Object
|
+----JBMSTours.aggregates.MaxButOneIntegerAggregator
- public class MaxButOneIntegerAggregator
- extends Object
- implements Externalizable, Aggregator
Implements the aggregation for MaxButONE when the input type is an
Integer.
We implement Externalizable to save space in case we
are written out (Serialization tends to take up a lot
of space).
-
MaxButOneIntegerAggregator()
- Niladic constructor
-
accumulate(ResultSet)
- Iteratively accumulates the addend into the aggregator.
-
getResult()
- Produces the result to be returned by the query.
-
getSecondValue()
- Returns the second highest value in the column found so far.
-
getTopValue()
- Returns the highest value in the column found so far.
-
initialize()
- Initializes the aggregate for processing.
-
merge(Aggregator)
- Merges one aggregator into a another aggregator.
-
newInstance()
- Return a new instance of this class.
-
readExternal(ObjectInput)
- Read in our two fields.
-
writeExternal(ObjectOutput)
- Write out our two fields.
MaxButOneIntegerAggregator
public MaxButOneIntegerAggregator()
- Niladic constructor
initialize
public void initialize()
- Initializes the aggregate for processing.
accumulate
public void accumulate(ResultSet addend) throws Throwable
- Iteratively accumulates the addend into the aggregator.
Called on each member of the set of values that is being
aggregated.
- Parameters:
- addend - the ResultSet addend (current input to
the aggregation)
- Throws: Throwable
- on error
merge
public void merge(Aggregator inputAggregator) throws Throwable
- Merges one aggregator into a another aggregator. Used in Group by.
- Parameters:
- inputAggregator - the other Aggregator
(input partial aggregate)
- Throws: Throwable
- on error
getResult
public Object getResult()
- Produces the result to be returned by the query.
The last processing of the aggregate.
In this instance, returns the second highest value in the column.
See
COM.cloudscape.aggregates.AggregateDefinition.getResult().
- Returns:
- the result column.
newInstance
public Aggregator newInstance()
- Return a new instance of this class. Identical
to Class.newInstance() but much cheaper because
reflection is costly.
Just implement it to do new myClass().
- Returns:
- Aggregator
getTopValue
public Integer getTopValue()
- Returns the highest value in the column found so far. This method
needs to be public because instances call each other during a
merge.
- Returns:
- topValue
getSecondValue
public Integer getSecondValue()
- Returns the second highest value in the column found so far. This method
needs to be public because instances call each other during a
merge.
- Returns:
- secondValue
writeExternal
public void writeExternal(ObjectOutput out) throws IOException
- Write out our two fields.
- Parameters:
- out - the output stream
- Throws: IOException
- on error
readExternal
public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException
- Read in our two fields.
- Parameters:
- int - the input stream
- Throws: IOException
- on error
- Throws: ClassNotFoundException
- on error
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