net.sf.reportengine.core.calc

Interface GroupCalculator<R,I extends CalcIntermResult<R>,V>

All Known Implementing Classes:

AbstractGroupCalculator, AvgGroupCalculator, CountGroupCalculator, FirstGroupCalculator, LastGroupCalculator, MaxGroupCalculator, MinGroupCalculator, SumGroupCalculator

public interface GroupCalculator<R,I extends CalcIntermResult<R>,V>

Interface for Group Calculators

Author:

dragos balan

Method Summary

Modifier and Type	Method and Description
I	compute(I intermResult, V newValue) compute the new value with the previous result and return a new result.
String	getLabel() returns the label to be displayed at the beginning of the total row.
I	init() this is used for initializing the intermediate result.

Method Detail

init

I init()

this is used for initializing the intermediate result.

Example: for a COUNT calculator the initial value should be zero (well, actually it should be an implementation of CalcIntermResult containing ZERO as data)

Returns:

the initial value of the intermediate result

compute

I compute(I intermResult,
          V newValue)

compute the new value with the previous result and return a new result.

Example: for a COUNT calculator after computing 10 records the next call to this method should be : compute(10, "whatever text"). This call should return 11.

Parameters:

intermResult - the previous intermediate result ( it's the 10 in my example)

newValue - the current value (it's the "whatever text" in my example above)

Returns:

getLabel

String getLabel()

returns the label to be displayed at the beginning of the total row. Example: 1. for a SumGroupCalculator this label should be "Total" so that each total row to display Total and Grand Total at the end 2. for a AvgGroupCalculator this label should be "Average"

Returns: