net.sf.ivmaidns.util
Class GComparator

java.lang.Object
  net.sf.ivmaidns.util.GComparator

All Implemented Interfaces:

java.io.Serializable, Immutable

Direct Known Subclasses:

DNSRecAltCmp, StrComparator

public class GComparator
extends java.lang.Object
implements Immutable, java.io.Serializable

Class for 'greater-than' comparators. A binary predicate, which tests whether the first its argument is greater than the second one, should extend this adapter class and override greater(Object, Object), implementing own comparison rules. Immutable interface is implemented to underline that such comparators must have constant internal state. The comparators may be used in serializable data structures since Serializable interface is implemented. In addition, this class provides the default comparator for objects of Sortable interface, and of String class and of the standard wrappers for the primitive types.

Since:

1.8

Version:

2.0

Author:

Ivan Maidanski

See Also:

Sortable, StrComparator, Serialized Form

Field Summary

static GComparator

INSTANCE The standard comparator for objects.

Constructor Summary

GComparator()
Constructs a new comparator.

Method Summary

boolean

greater(java.lang.Object objA, java.lang.Object objB) The body of 'Greater-Than' comparator.

Methods inherited from class java.lang.Object

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

Field Detail

INSTANCE

public static final GComparator INSTANCE

The standard comparator for objects. This constant field is initialized with the instantiation of exactly this comparator. The implemented standard comparator correctly orders any two objects of the class which implements Sortable interface, or both of String class, or both of the same primary-type value wrapper.

See Also:

greater(java.lang.Object, java.lang.Object)

Constructor Detail

GComparator

public GComparator()

Constructs a new comparator. This constructor is made public to allow custom dynamic instantiation of this class.

See Also:

INSTANCE

Method Detail

greater

public boolean greater(java.lang.Object objA,
                       java.lang.Object objB)

The body of 'Greater-Than' comparator. Tests whether or not the first specified object is greater than the second one (according to the semantics). This method should be overridden in the adapter subclasses. If any argument is not instance of the expected type then standard comparison should be performed (which is implemented in this method of this class). The standard comparison of two objects is as follows: if objA == objB then false is returned else if objA is instance of Sortable then greaterThan(objB) for objA is returned else if objB is instance of Sortable then !greaterThan(objA) for objB is returned, else if objA is null then true is returned, else if objA and objB are both of the same class (either Boolean, Byte, Short, Integer, Long, Float, Double, Character or String) and the first (primary) value is greater than the second one then true else false is returned. Important notes: String objects are compared here in the case-sensitive manner; Float and Double objects are compared here handling their zero and NaN values specially (0 is greater than -0 and NaN is greater than non-NaN).

Parameters:

objA - the first compared argument (may be null).

objB - the second compared argument (may be null).

Returns:

true if and only if objA is greater than objB.

See Also:

INSTANCE