org.pentaho.reporting.engine.classic.core.function
Class CountDistinctFunction

java.lang.Object
  org.pentaho.reporting.engine.classic.core.function.AbstractExpression
      org.pentaho.reporting.engine.classic.core.function.AbstractFunction
          org.pentaho.reporting.engine.classic.core.function.CountDistinctFunction

All Implemented Interfaces:

Serializable, Cloneable, EventListener, ReportListener, AggregationFunction, Expression, FieldAggregationFunction, Function

public class CountDistinctFunction
extends AbstractFunction
implements FieldAggregationFunction

Counts the distinct occurences of an certain value of an column. This functionality is similiar to the SQL distinct() function.

Author:

Thomas Morgner

See Also:

Serialized Form

Constructor Summary

CountDistinctFunction()
DefaultConstructor.

Method Summary

Object	clone() Clones the expression.
String	getField() Returns the field used by the function.
String	getGroup() Returns the group name.
Expression	getInstance() Return a completly separated copy of this function.
Object	getValue() Return the number of distint values for the given column.
void	groupStarted(ReportEvent event) Receives notification that a group has started.
void	itemsAdvanced(ReportEvent event) Receives notification that a row of data is being processed.
void	reportInitialized(ReportEvent event) Receives notification that report generation initializes the current run.
void	setField(String field) Sets the field name for the function.
void	setGroup(String name) Sets the group name.

Methods inherited from class org.pentaho.reporting.engine.classic.core.function.AbstractFunction

groupFinished, itemsFinished, itemsStarted, reportDone, reportFinished, reportStarted

Methods inherited from class org.pentaho.reporting.engine.classic.core.function.AbstractExpression

getDataRow, getDependencyLevel, getName, getReportConfiguration, getResourceBundleFactory, getRuntime, isActive, isDeepTraversing, isPreserve, setActive, setDependencyLevel, setName, setPreserve, setRuntime

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.pentaho.reporting.engine.classic.core.event.ReportListener

groupFinished, itemsFinished, itemsStarted, reportDone, reportFinished, reportStarted

Methods inherited from interface org.pentaho.reporting.engine.classic.core.function.Expression

getDataRow, getDependencyLevel, getName, getReportConfiguration, getResourceBundleFactory, getRuntime, isActive, isDeepTraversing, isPreserve, setDependencyLevel, setName, setRuntime

Constructor Detail

CountDistinctFunction

public CountDistinctFunction()

DefaultConstructor.

Method Detail

getGroup

public String getGroup()

Returns the group name.

Specified by:

getGroup in interface AggregationFunction

Returns:

The group name.

setGroup

public void setGroup(String name)

Sets the group name.

If a group is defined, the running total is reset to zero at the start of every instance of this group.

Specified by:

setGroup in interface AggregationFunction

Parameters:

name - the group name (null permitted).

getField

public String getField()

Returns the field used by the function. The field name corresponds to a column name in the report's data-row.

Specified by:

getField in interface FieldAggregationFunction

Returns:

The field name.

setField

public void setField(String field)

Sets the field name for the function. The field name corresponds to a column name in the report's data-row.

Specified by:

setField in interface FieldAggregationFunction

Parameters:

field - the field name.

reportInitialized

public void reportInitialized(ReportEvent event)

Receives notification that report generation initializes the current run.

The event carries a ReportState.Started state. Use this to initialize the report.

Specified by:

reportInitialized in interface ReportListener

Overrides:

reportInitialized in class AbstractFunction

Parameters:

event - The event.

groupStarted

public void groupStarted(ReportEvent event)

Receives notification that a group has started.

Specified by:

groupStarted in interface ReportListener

Overrides:

groupStarted in class AbstractFunction

Parameters:

event - the event.

itemsAdvanced

public void itemsAdvanced(ReportEvent event)

Receives notification that a row of data is being processed.

Specified by:

itemsAdvanced in interface ReportListener

Overrides:

itemsAdvanced in class AbstractFunction

Parameters:

event - the event.

getValue

public Object getValue()

Return the number of distint values for the given column.

Specified by:

getValue in interface Expression

Returns:

the value of the function.

getInstance

public Expression getInstance()

Return a completly separated copy of this function. The copy does no longer share any changeable objects with the original function.

Specified by:

getInstance in interface Expression

Overrides:

getInstance in class AbstractExpression

Returns:

a copy of this function.

clone

public Object clone()
             throws CloneNotSupportedException

Clones the expression. The expression should be reinitialized after the cloning.

Expressions maintain no state, cloning is done at the beginning of the report processing to disconnect the expression from any other object space.

Specified by:

clone in interface Expression

Overrides:

clone in class AbstractExpression

Returns:

a clone of this expression.

Throws:

CloneNotSupportedException - this should never happen.