org.microbean.configuration.spi

Class RankedComparator<T>

java.lang.Object

org.microbean.configuration.spi.RankedComparator<T>

Type Parameters:

T - the type of object to compare

All Implemented Interfaces:

Serializable, Comparator<T>

public class RankedComparator<T>
extends Object
implements Comparator<T>, Serializable

A Comparator that ranks other objects for comparison purposes.

A rank for the purposes of this class is a positive integer. One integer representing a rank outranks another integer representing a rank if the first integer is greater than the second. Hence, e.g., 1 outranks 0. A negative integer cannot represent a rank and in the context of ranking means, effectively, that any rank it might otherwise represent is unknown.

A RankedComparator can accept an optional List at construction time that can be used for ranking purposes in case the type of objects the RankedComparator compares are not instances of Ranked. In such a case, the index of an object in a reversed copy of the supplied List is used as its rank.

Author:

Laird Nelson

See Also:

RankedComparator(List), compare(Object, Object), Serialized Form

Constructor Summary

Constructors

Constructor and Description
RankedComparator() Creates a new RankedComparator.
RankedComparator(List<?> items) Creates a new RankedComparator.

Method Summary

Modifier and Type	Method and Description
int	compare(T one, T two) Compares two objects, returning -1 if one outranks two, 1 if two outranks one, and 0 if the two objects are either ranked equally or their ranks could not be determined.
protected Object	getComparisonObject(T realObject) Given an object to be compared, returns the Object that should be used to determine ranking (as determined by the List supplied at construction time).
boolean	ranks(T object) Returns true if this RankedComparator explicitly ranks the supplied 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

comparing, comparing, comparingDouble, comparingInt, comparingLong, equals, naturalOrder, nullsFirst, nullsLast, reversed, reverseOrder, thenComparing, thenComparing, thenComparing, thenComparingDouble, thenComparingInt, thenComparingLong

Constructor Detail

RankedComparator

public RankedComparator()

Creates a new RankedComparator.

See Also:

RankedComparator(List)

RankedComparator

public RankedComparator(List<?> items)

Creates a new RankedComparator.

Parameters:

items - a List of Objects that will be used for ranking purposes; may be null; the item at position 0 is deemed to outrank all others; copied by value

See Also:

getComparisonObject(Object)

Method Detail

ranks

public final boolean ranks(T object)

Returns true if this RankedComparator explicitly ranks the supplied object.

Parameters:

object - the object to test; may be null

Returns:

true if this RankedComparator explicitly ranks the supplied object; false otherwise

See Also:

getComparisonObject(Object)

compare

public final int compare(T one,
                         T two)

Compares two objects, returning -1 if one outranks two, 1 if two outranks one, and 0 if the two objects are either ranked equally or their ranks could not be determined.

This method makes use of the List supplied at construction time for ranking information.

Non-null objects outrank null objects.

Specified by:

compare in interface Comparator<T>

Parameters:

one - the first object; may be null

two - the second object; may be null

Returns:

-1 if one outranks two, 1 if two outranks one, and 0 if the two objects are either ranked equally or their ranks could not be determined

See Also:

getComparisonObject(Object), RankedComparator(List)

getComparisonObject

protected Object getComparisonObject(T realObject)

Given an object to be compared, returns the Object that should be used to determine ranking (as determined by the List supplied at construction time).

This method may return null.

Overrides of this method may return null.

The default implementation of this method simply returns the supplied realObject parameter value.

Parameters:

realObject - the object to be compared; may be null

Returns:

the Object that should be used to determine ranking (as determined by the List supplied at construction time), possibly null

See Also:

RankedComparator(List), compare(Object, Object)