org.apache.commons.lang.builder
public class CompareToBuilder extends Object
equals(Object)
and
hashcode()
built with {@link EqualsBuilder} and
{@link HashCodeBuilder}.
Two Objects that compare equal using equals(Object)
should normally
also compare equal using compareTo(Object)
.
All relevant fields should be included in the calculation of the
comparison. Derived fields may be ignored. The same fields, in the same
order, should be used in both compareTo(Object)
and
equals(Object)
.
To use this class write code as follows:
public class MyClass { String field1; int field2; boolean field3; ... public int compareTo(Object o) { MyClass myClass = (MyClass) o; return new CompareToBuilder() .appendSuper(super.compareTo(o) .append(this.field1, myClass.field1) .append(this.field2, myClass.field2) .append(this.field3, myClass.field3) .toComparison(); } }
Alternatively, there is are {@link #reflectionCompare reflectionCompare} method that uses
reflection to determine the fields to append. Because fields can be private,
reflectionCompare
uses {@link java.lang.reflect.AccessibleObject#setAccessible(boolean)} to
bypass normal access control checks. This will fail under a security manager,
unless the appropriate permissions are set up correctly. It is also
slower than appending explicitly.
A typical implementation of compareTo(Object)
using
reflectionCompare
looks like:
public int compareTo(Object o) { return CompareToBuilder.reflectionCompare(this, o); }
Since: 1.0
Version: $Id: CompareToBuilder.java 161243 2005-04-14 04:30:28Z ggregory $
See Also: java.lang.Comparable java.lang.Object#equals(Object) java.lang.Object#hashCode() EqualsBuilder HashCodeBuilder
Constructor Summary | |
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CompareToBuilder() Constructor for CompareToBuilder. Starts off assuming that the objects are equal. |
Method Summary | |
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CompareToBuilder | append(Object lhs, Object rhs) Appends to the
|
CompareToBuilder | append(Object lhs, Object rhs, Comparator comparator) Appends to the
If |
CompareToBuilder | append(long lhs, long rhs)
Appends to the builder the comparison of
two long s.
|
CompareToBuilder | append(int lhs, int rhs)
Appends to the builder the comparison of
two int s.
|
CompareToBuilder | append(short lhs, short rhs)
Appends to the builder the comparison of
two short s.
|
CompareToBuilder | append(char lhs, char rhs)
Appends to the builder the comparison of
two char s.
|
CompareToBuilder | append(byte lhs, byte rhs)
Appends to the builder the comparison of
two byte s.
|
CompareToBuilder | append(double lhs, double rhs) Appends to the This handles NaNs, Infinities, and It is compatible with the hash code generated by
|
CompareToBuilder | append(float lhs, float rhs) Appends to the This handles NaNs, Infinities, and It is compatible with the hash code generated by
|
CompareToBuilder | append(boolean lhs, boolean rhs)
Appends to the builder the comparison of
two booleans s.
|
CompareToBuilder | append(Object[] lhs, Object[] rhs) Appends to the
This method will also will be called for the top level of multi-dimensional, ragged, and multi-typed arrays. |
CompareToBuilder | append(Object[] lhs, Object[] rhs, Comparator comparator) Appends to the
This method will also will be called for the top level of multi-dimensional, ragged, and multi-typed arrays. |
CompareToBuilder | append(long[] lhs, long[] rhs) Appends to the
|
CompareToBuilder | append(int[] lhs, int[] rhs) Appends to the
|
CompareToBuilder | append(short[] lhs, short[] rhs) Appends to the
|
CompareToBuilder | append(char[] lhs, char[] rhs) Appends to the
|
CompareToBuilder | append(byte[] lhs, byte[] rhs) Appends to the
|
CompareToBuilder | append(double[] lhs, double[] rhs) Appends to the
|
CompareToBuilder | append(float[] lhs, float[] rhs) Appends to the
|
CompareToBuilder | append(boolean[] lhs, boolean[] rhs) Appends to the
|
CompareToBuilder | appendSuper(int superCompareTo) Appends to the |
static int | reflectionCompare(Object lhs, Object rhs) Compares two Fields can be private, thus |
static int | reflectionCompare(Object lhs, Object rhs, boolean compareTransients) Compares two Fields can be private, thus |
static int | reflectionCompare(Object lhs, Object rhs, boolean compareTransients, Class reflectUpToClass) Compares two Fields can be private, thus |
int | toComparison()
Returns a negative integer, a positive integer, or zero as
the builder has judged the "left-hand" side
as less than, greater than, or equal to the "right-hand"
side.
|
Constructor for CompareToBuilder.
Starts off assuming that the objects are equal. Multiple calls are then made to the various append methods, followed by a call to {@link #toComparison} to get the result.
Appends to the builder
the comparison of
two Object
s.
lhs == rhs
lhs
or rhs
is null
,
a null
object is less than a non-null
objectlhs
must either be an array or implement {@link Comparable}.
Parameters: lhs left-hand object rhs right-hand object
Returns: this - used to chain append calls
Throws: ClassCastException if rhs
is not assignment-compatible
with lhs
Appends to the builder
the comparison of
two Object
s.
lhs == rhs
lhs
or rhs
is null
,
a null
object is less than a non-null
objectIf lhs
is an array, array comparison methods will be used.
Otherwise comparator
will be used to compare the objects.
If comparator
is null
, lhs
must
implement {@link Comparable} instead.
Parameters: lhs left-hand object rhs right-hand object comparator Comparator
used to compare the objects,
null
means treat lhs as Comparable
Returns: this - used to chain append calls
Throws: ClassCastException if rhs
is not assignment-compatible
with lhs
Since: 2.0
builder
the comparison of
two long
s.
Parameters: lhs left-hand value rhs right-hand value
Returns: this - used to chain append calls
builder
the comparison of
two int
s.
Parameters: lhs left-hand value rhs right-hand value
Returns: this - used to chain append calls
builder
the comparison of
two short
s.
Parameters: lhs left-hand value rhs right-hand value
Returns: this - used to chain append calls
builder
the comparison of
two char
s.
Parameters: lhs left-hand value rhs right-hand value
Returns: this - used to chain append calls
builder
the comparison of
two byte
s.
Parameters: lhs left-hand value rhs right-hand value
Returns: this - used to chain append calls
Appends to the builder
the comparison of
two double
s.
This handles NaNs, Infinities, and -0.0
.
It is compatible with the hash code generated by
HashCodeBuilder
.
Parameters: lhs left-hand value rhs right-hand value
Returns: this - used to chain append calls
Appends to the builder
the comparison of
two float
s.
This handles NaNs, Infinities, and -0.0
.
It is compatible with the hash code generated by
HashCodeBuilder
.
Parameters: lhs left-hand value rhs right-hand value
Returns: this - used to chain append calls
builder
the comparison of
two booleans
s.
Parameters: lhs left-hand value rhs right-hand value
Returns: this - used to chain append calls
Appends to the builder
the deep comparison of
two Object
arrays.
==
null
, null
is less than non-null
This method will also will be called for the top level of multi-dimensional, ragged, and multi-typed arrays.
Parameters: lhs left-hand array rhs right-hand array
Returns: this - used to chain append calls
Throws: ClassCastException if rhs
is not assignment-compatible
with lhs
Appends to the builder
the deep comparison of
two Object
arrays.
==
null
, null
is less than non-null
This method will also will be called for the top level of multi-dimensional, ragged, and multi-typed arrays.
Parameters: lhs left-hand array rhs right-hand array comparator Comparator
to use to compare the array elements,
null
means to treat lhs
elements as Comparable
.
Returns: this - used to chain append calls
Throws: ClassCastException if rhs
is not assignment-compatible
with lhs
Since: 2.0
Appends to the builder
the deep comparison of
two long
arrays.
==
null
, null
is less than non-null
Parameters: lhs left-hand array rhs right-hand array
Returns: this - used to chain append calls
Appends to the builder
the deep comparison of
two int
arrays.
==
null
, null
is less than non-null
Parameters: lhs left-hand array rhs right-hand array
Returns: this - used to chain append calls
Appends to the builder
the deep comparison of
two short
arrays.
==
null
, null
is less than non-null
Parameters: lhs left-hand array rhs right-hand array
Returns: this - used to chain append calls
Appends to the builder
the deep comparison of
two char
arrays.
==
null
, null
is less than non-null
Parameters: lhs left-hand array rhs right-hand array
Returns: this - used to chain append calls
Appends to the builder
the deep comparison of
two byte
arrays.
==
null
, null
is less than non-null
Parameters: lhs left-hand array rhs right-hand array
Returns: this - used to chain append calls
Appends to the builder
the deep comparison of
two double
arrays.
==
null
, null
is less than non-null
Parameters: lhs left-hand array rhs right-hand array
Returns: this - used to chain append calls
Appends to the builder
the deep comparison of
two float
arrays.
==
null
, null
is less than non-null
Parameters: lhs left-hand array rhs right-hand array
Returns: this - used to chain append calls
Appends to the builder
the deep comparison of
two boolean
arrays.
==
null
, null
is less than non-null
Parameters: lhs left-hand array rhs right-hand array
Returns: this - used to chain append calls
Appends to the builder
the compareTo(Object)
result of the superclass.
Parameters: superCompareTo result of calling super.compareTo(Object)
Returns: this - used to chain append calls
Since: 2.0
Compares two Object
s via reflection.
Fields can be private, thus AccessibleObject.setAccessible
is used to bypass normal access control checks. This will fail under a
security manager unless the appropriate permissions are set.
If both lhs
and rhs
are null
,
they are considered equal.
Parameters: lhs left-hand object rhs right-hand object
Returns: a negative integer, zero, or a positive integer as lhs
is less than, equal to, or greater than rhs
Throws: NullPointerException if either (but not both) parameters are
null
ClassCastException if rhs
is not assignment-compatible
with lhs
Compares two Object
s via reflection.
Fields can be private, thus AccessibleObject.setAccessible
is used to bypass normal access control checks. This will fail under a
security manager unless the appropriate permissions are set.
compareTransients
is true
,
compares transient members. Otherwise ignores them, as they
are likely derived fields.If both lhs
and rhs
are null
,
they are considered equal.
Parameters: lhs left-hand object rhs right-hand object compareTransients whether to compare transient fields
Returns: a negative integer, zero, or a positive integer as lhs
is less than, equal to, or greater than rhs
Throws: NullPointerException if either lhs
or rhs
(but not both) is null
ClassCastException if rhs
is not assignment-compatible
with lhs
Compares two Object
s via reflection.
Fields can be private, thus AccessibleObject.setAccessible
is used to bypass normal access control checks. This will fail under a
security manager unless the appropriate permissions are set.
compareTransients
is true
,
compares transient members. Otherwise ignores them, as they
are likely derived fields.reflectUpToClass
.
If reflectUpToClass
is null
, compares all superclass fields.If both lhs
and rhs
are null
,
they are considered equal.
Parameters: lhs left-hand object rhs right-hand object compareTransients whether to compare transient fields reflectUpToClass last superclass for which fields are compared
Returns: a negative integer, zero, or a positive integer as lhs
is less than, equal to, or greater than rhs
Throws: NullPointerException if either lhs
or rhs
(but not both) is null
ClassCastException if rhs
is not assignment-compatible
with lhs
Since: 2.0
builder
has judged the "left-hand" side
as less than, greater than, or equal to the "right-hand"
side.
Returns: final comparison result