net.sf.reportengine.core.calc

Class AvgGroupCalculator

java.lang.Object

net.sf.reportengine.core.calc.AbstractGroupCalculator<BigDecimal,AvgCalcIntermResult<BigDecimal>,Object>

net.sf.reportengine.core.calc.AvgGroupCalculator

All Implemented Interfaces:

GroupCalculator<BigDecimal,AvgCalcIntermResult<BigDecimal>,Object>

public class AvgGroupCalculator
extends AbstractGroupCalculator<BigDecimal,AvgCalcIntermResult<BigDecimal>,Object>

Universal average calculator. This calculator is not optimized because:

• it accepts any values (i.e java.lang.Object objects and tries to convert them into BigDecimals (by using the conversion new BigDecimal(object.toString()).
• The whole internal computation is based on BigDecimals.

You are strongly encouraged to write your own avg calculator based on your needs and using your own types .

Author:

dragos balan

Field Summary

Fields

Modifier and Type	Field and Description
static String	LABEL the label for this calculator

Constructor Summary

Constructors

Constructor and Description
AvgGroupCalculator() Default constructor ( label = "Average" number of exact decimals = 32 )
AvgGroupCalculator(String label) average group calculator constructor on which you can set the label ( number of exact decimal = 32)
AvgGroupCalculator(String label, MathContext mathContext) use this constructor if you want to control the number exact decimals

Method Summary

Modifier and Type	Method and Description
AvgCalcIntermResult<BigDecimal>	compute(AvgCalcIntermResult<BigDecimal> intermResult, Object newValue) this compute method is based on the following formula: AVG[n+1] = (n * AVG[n] + element[n+1] ) / (n+1)
AvgCalcIntermResult<BigDecimal>	init() init method required by the GroupCalculator

Methods inherited from class net.sf.reportengine.core.calc.AbstractGroupCalculator

getLabel

Methods inherited from class java.lang.Object

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

Field Detail

LABEL

public static final String LABEL

the label for this calculator

See Also:

Constant Field Values

Constructor Detail

AvgGroupCalculator

public AvgGroupCalculator()

Default constructor ( label = "Average" number of exact decimals = 32 )

AvgGroupCalculator

public AvgGroupCalculator(String label)

average group calculator constructor on which you can set the label ( number of exact decimal = 32)

Parameters:

label - the label to be displayed on each totals row

AvgGroupCalculator

public AvgGroupCalculator(String label,
                          MathContext mathContext)

use this constructor if you want to control the number exact decimals

Parameters:

label - the label to be displayed on each total row

mathContext - the math context for BigDecimal operations

Method Detail

init

public AvgCalcIntermResult<BigDecimal> init()

init method required by the GroupCalculator

Returns:

the initial value of the intermediate result

compute

public AvgCalcIntermResult<BigDecimal> compute(AvgCalcIntermResult<BigDecimal> intermResult,
                                               Object newValue)

this compute method is based on the following formula: AVG[n+1] = (n * AVG[n] + element[n+1] ) / (n+1)

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: