org.apache.commons.collections.comparators
Class NullComparator
java.lang.Objectorg.apache.commons.collections.comparators.NullComparator
- Comparator, Serializable
public class NullComparator
extends java.lang.Object
implements Comparator, Serializable
A Comparator that will compare nulls to be either lower or higher than
other objects.
$Revision: 155406 $ $Date: 2005-02-26 12:55:26 +0000 (Sat, 26 Feb 2005) $NullComparator()- Construct an instance that sorts
null higher than any
non-null object it is compared with.
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NullComparator(Comparator nonNullComparator)- Construct an instance that sorts
null higher than any
non-null object it is compared with.
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NullComparator(Comparator nonNullComparator, boolean nullsAreHigh)- Construct an instance that sorts
null higher or lower than
any non-null object it is compared with.
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NullComparator(boolean nullsAreHigh)- Construct an instance that sorts
null higher or lower than
any non-null object it is compared with.
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int | compare(Object o1, Object o2)- Perform a comparison between two objects.
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boolean | equals(Object obj)- Determines whether the specified object represents a comparator that is
equal to this comparator.
|
int | hashCode()- Implement a hash code for this comparator that is consistent with
equals(Object).
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NullComparator
public NullComparator()
Construct an instance that sorts
null higher than any
non-
null object it is compared with. When comparing two
non-
null objects, the
ComparableComparator is
used.
NullComparator
public NullComparator(Comparator nonNullComparator)
Construct an instance that sorts null higher than any
non-null object it is compared with. When comparing two
non-null objects, the specified Comparator is
used.
nonNullComparator - the comparator to use when comparing two
non-null objects. This argument cannot be
null
NullComparator
public NullComparator(Comparator nonNullComparator,
boolean nullsAreHigh) Construct an instance that sorts null higher or lower than
any non-null object it is compared with. When comparing
two non-null objects, the specified Comparator is
used.
nonNullComparator - the comparator to use when comparing two
non-null objects. This argument cannot be
nullnullsAreHigh - a true value indicates that
null should be compared as higher than a
non-null object. A false value indicates
that null should be compared as lower than a
non-null object.
NullComparator
public NullComparator(boolean nullsAreHigh)
Construct an instance that sorts
null higher or lower than
any non-
null object it is compared with. When comparing
two non-
null objects, the
ComparableComparator is
used.
nullsAreHigh - a true value indicates that
null should be compared as higher than a
non-null object. A false value indicates
that null should be compared as lower than a
non-null object.
compare
public int compare(Object o1,
Object o2) Perform a comparison between two objects. If both objects are
null, a 0 value is returned. If one object
is null and the other is not, the result is determined on
whether the Comparator was constructed to have nulls as higher or lower
than other objects. If neither object is null, an
underlying comparator specified in the constructor (or the default) is
used to compare the non-null objects.
o1 - the first object to compareo2 - the object to compare it to.
-1 if o1 is "lower" than (less than,
before, etc.) o2; 1 if o1 is
"higher" than (greater than, after, etc.) o2; or
0 if o1 and o2 are equal.
equals
public boolean equals(Object obj)
Determines whether the specified object represents a comparator that is
equal to this comparator.
obj - the object to compare this comparator with.
true if the specified object is a NullComparator
with equivalent null comparison behavior
(i.e. null high or low) and with equivalent underlying
non-null object comparators.
hashCode
public int hashCode()
Implement a hash code for this comparator that is consistent with
equals(Object).
- a hash code for this comparator.
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