Package com.tangosol.util.comparator

Class ExtractorComparator<T>

java.lang.Object

com.tangosol.util.comparator.ExtractorComparator<T>

All Implemented Interfaces:

ExternalizableLite, PortableObject, QueryMapComparator<T>, Serializable, Comparator<T>

public class ExtractorComparator<T>
extends Object
implements QueryMapComparator<T>, ExternalizableLite, PortableObject

Comparator implementation that uses specified ValueExtractor to extract value(s) to be used for comparison.

Author:

as 2010.09.09

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor	Description
ExtractorComparator()	Default constructor (for PortableObject).
ExtractorComparator(ValueExtractor<? super T,? extends E> extractor)	Construct a ExtractorComparator with the specified extractor.

Method Summary

Modifier and Type	Method	Description
int	compare(T o1, T o2)	Compares extracted values (by specified ValueExtractor) of given arguments for order.
int	compareEntries(QueryMap.Entry entry1, QueryMap.Entry entry2)	Compare two entries based on the rules specified by Comparator.
ValueExtractor<? super T,? extends Comparable>	getExtractor()	Returns the ValueExtractor to extract value(s) to be used in comparison.
void	readExternal(PofReader in)	Restore the contents of a user type instance by reading its state using the specified PofReader object.
void	readExternal(DataInput in)	Restore the contents of this object by loading the object's state from the passed DataInput object.
void	writeExternal(PofWriter out)	Save the contents of a POF user type instance by writing its state using the specified PofWriter object.
void	writeExternal(DataOutput out)	Save the contents of this object by storing the object's state into the passed DataOutput object.

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Comparator

equals, reversed, thenComparing, thenComparing, thenComparing, thenComparingDouble, thenComparingInt, thenComparingLong

Constructor Detail

ExtractorComparator

public ExtractorComparator()

Default constructor (for PortableObject).

ExtractorComparator

public ExtractorComparator(ValueExtractor<? super T,? extends E> extractor)

Construct a ExtractorComparator with the specified extractor.

Parameters:

extractor - the ValueExtractor to use by this filter

Method Detail

compare

public int compare(T o1,
                   T o2)

Compares extracted values (by specified ValueExtractor) of given arguments for order.

Specified by:

compare in interface Comparator<T>

Parameters:

o1 - the first object to be compared

o2 - the second object to be compared

Returns:

a negative integer, zero, or a positive integer as the first argument is less than, equal to, or greater than the second

Throws:

ClassCastException - if the arguments' types prevent them from being compared by this Comparator.

compareEntries

public int compareEntries(QueryMap.Entry entry1,
                          QueryMap.Entry entry2)

Description copied from interface: QueryMapComparator

Compare two entries based on the rules specified by Comparator.

If possible, use the extract method to optimize the value extraction process.

This method is expected to be implemented by Comparator wrappers, such as ChainedComparator and InverseComparator, which simply pass on this invocation to the wrapped Comparator objects if they too implement this interface, or to invoke their default compare method passing the actual objects (not the extracted values) obtained from the extractor using the passed entries.

This interface is also expected to be implemented by ValueExtractor implementations that implement the Comparator interface. It is expected that in most cases, the Comparator wrappers will eventually terminate at (i.e. delegate to) ValueExtractors that also implement this interface.

Specified by:

compareEntries in interface QueryMapComparator<T>

Parameters:

entry1 - the first entry to compare values from; read-only

entry2 - the second entry to compare values from; read-only

Returns:

a negative integer, zero, or a positive integer as the first entry denotes a value that is is less than, equal to, or greater than the value denoted by the second entry

readExternal

public void readExternal(DataInput in)
                  throws IOException

Description copied from interface: ExternalizableLite

Restore the contents of this object by loading the object's state from the passed DataInput object.

Specified by:

readExternal in interface ExternalizableLite

Parameters:

in - the DataInput stream to read data from in order to restore the state of this object

Throws:

IOException - if an I/O exception occurs

NotActiveException - if the object is not in its initial state, and therefore cannot be deserialized into

writeExternal

public void writeExternal(DataOutput out)
                   throws IOException

Description copied from interface: ExternalizableLite

Save the contents of this object by storing the object's state into the passed DataOutput object.

Specified by:

writeExternal in interface ExternalizableLite

Parameters:

out - the DataOutput stream to write the state of this object to

Throws:

IOException - if an I/O exception occurs

readExternal

public void readExternal(PofReader in)
                  throws IOException

Description copied from interface: PortableObject

Restore the contents of a user type instance by reading its state using the specified PofReader object.

Specified by:

readExternal in interface PortableObject

Parameters:

in - the PofReader from which to read the object's state

Throws:

IOException - if an I/O error occurs

writeExternal

public void writeExternal(PofWriter out)
                   throws IOException

Description copied from interface: PortableObject

Save the contents of a POF user type instance by writing its state using the specified PofWriter object.

Specified by:

writeExternal in interface PortableObject

Parameters:

out - the PofWriter to which to write the object's state

Throws:

IOException - if an I/O error occurs

getExtractor

public ValueExtractor<? super T,? extends Comparable> getExtractor()

Returns the ValueExtractor to extract value(s) to be used in comparison.

Returns:

the ValueExtractor to extract value(s) to be used in comparison