public class CompareToBuilder extends Object implements Builder<Integer>
Comparable.compareTo(Object) methods.
It is consistent with equals(Object) and
hashcode() built with EqualsBuilder and
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();
}
}
Values are compared in the order they are appended to the builder. If any comparison returns
a non-zero result, then that value will be the result returned by toComparison() and all
subsequent comparisons are skipped.
Alternatively, there are reflectionCompare methods that use
reflection to determine the fields to append. Because fields can be private,
reflectionCompare uses 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);
}
The reflective methods compare object fields in the order returned by
Class.getDeclaredFields(). The fields of the class are compared first, followed by those
of its parent classes (in order from the bottom to the top of the class hierarchy).
Comparable,
Object.equals(Object),
Object.hashCode(),
EqualsBuilder,
HashCodeBuilder| Constructor and Description |
|---|
CompareToBuilder()
Constructor for CompareToBuilder.
|
| Modifier and Type | Method and Description |
|---|---|
CompareToBuilder |
append(boolean[] lhs,
boolean[] rhs)
Appends to the
builder the deep comparison of
two boolean arrays. |
CompareToBuilder |
append(boolean lhs,
boolean rhs)
Appends to the
builder the comparison of
two booleanss. |
CompareToBuilder |
append(byte[] lhs,
byte[] rhs)
Appends to the
builder the deep comparison of
two byte arrays. |
CompareToBuilder |
append(byte lhs,
byte rhs)
Appends to the
builder the comparison of
two bytes. |
CompareToBuilder |
append(char[] lhs,
char[] rhs)
Appends to the
builder the deep comparison of
two char arrays. |
CompareToBuilder |
append(char lhs,
char rhs)
Appends to the
builder the comparison of
two chars. |
CompareToBuilder |
append(double[] lhs,
double[] rhs)
Appends to the
builder the deep comparison of
two double arrays. |
CompareToBuilder |
append(double lhs,
double rhs)
Appends to the
builder the comparison of
two doubles. |
CompareToBuilder |
append(float[] lhs,
float[] rhs)
Appends to the
builder the deep comparison of
two float arrays. |
CompareToBuilder |
append(float lhs,
float rhs)
Appends to the
builder the comparison of
two floats. |
CompareToBuilder |
append(int[] lhs,
int[] rhs)
Appends to the
builder the deep comparison of
two int arrays. |
CompareToBuilder |
append(int lhs,
int rhs)
Appends to the
builder the comparison of
two ints. |
CompareToBuilder |
append(long[] lhs,
long[] rhs)
Appends to the
builder the deep comparison of
two long arrays. |
CompareToBuilder |
append(long lhs,
long rhs)
Appends to the
builder the comparison of
two longs. |
CompareToBuilder |
append(Object[] lhs,
Object[] rhs)
Appends to the
builder the deep comparison of
two Object arrays. |
CompareToBuilder |
append(Object[] lhs,
Object[] rhs,
Comparator<?> comparator)
Appends to the
builder the deep comparison of
two Object arrays. |
CompareToBuilder |
append(Object lhs,
Object rhs)
Appends to the
builder the comparison of
two Objects. |
CompareToBuilder |
append(Object lhs,
Object rhs,
Comparator<?> comparator)
Appends to the
builder the comparison of
two Objects. |
CompareToBuilder |
append(short[] lhs,
short[] rhs)
Appends to the
builder the deep comparison of
two short arrays. |
CompareToBuilder |
append(short lhs,
short rhs)
Appends to the
builder the comparison of
two shorts. |
CompareToBuilder |
appendSuper(int superCompareTo)
Appends to the
builder the compareTo(Object)
result of the superclass. |
Integer |
build()
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. |
static int |
reflectionCompare(Object lhs,
Object rhs)
Compares two
Objects via reflection. |
static int |
reflectionCompare(Object lhs,
Object rhs,
boolean compareTransients)
Compares two
Objects via reflection. |
static int |
reflectionCompare(Object lhs,
Object rhs,
boolean compareTransients,
Class<?> reflectUpToClass,
String... excludeFields)
Compares two
Objects via reflection. |
static int |
reflectionCompare(Object lhs,
Object rhs,
Collection<String> excludeFields)
Compares two
Objects via reflection. |
static int |
reflectionCompare(Object lhs,
Object rhs,
String... excludeFields)
Compares two
Objects via reflection. |
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. |
public CompareToBuilder()
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
toComparison() to get the result.
public static int reflectionCompare(Object lhs, Object rhs)
Compares two Objects 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.
lhs - left-hand objectrhs - right-hand objectlhs
is less than, equal to, or greater than rhsNullPointerException - if either (but not both) parameters are
nullClassCastException - if rhs is not assignment-compatible
with lhspublic static int reflectionCompare(Object lhs, Object rhs, boolean compareTransients)
Compares two Objects 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.
lhs - left-hand objectrhs - right-hand objectcompareTransients - whether to compare transient fieldslhs
is less than, equal to, or greater than rhsNullPointerException - if either lhs or rhs
(but not both) is nullClassCastException - if rhs is not assignment-compatible
with lhspublic static int reflectionCompare(Object lhs, Object rhs, Collection<String> excludeFields)
Compares two Objects 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.
lhs - left-hand objectrhs - right-hand objectexcludeFields - Collection of String fields to excludelhs
is less than, equal to, or greater than rhsNullPointerException - if either lhs or rhs
(but not both) is nullClassCastException - if rhs is not assignment-compatible
with lhspublic static int reflectionCompare(Object lhs, Object rhs, String... excludeFields)
Compares two Objects 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.
lhs - left-hand objectrhs - right-hand objectexcludeFields - array of fields to excludelhs
is less than, equal to, or greater than rhsNullPointerException - if either lhs or rhs
(but not both) is nullClassCastException - if rhs is not assignment-compatible
with lhspublic static int reflectionCompare(Object lhs, Object rhs, boolean compareTransients, Class<?> reflectUpToClass, String... excludeFields)
Compares two Objects 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.
lhs - left-hand objectrhs - right-hand objectcompareTransients - whether to compare transient fieldsreflectUpToClass - last superclass for which fields are comparedexcludeFields - fields to excludelhs
is less than, equal to, or greater than rhsNullPointerException - if either lhs or rhs
(but not both) is nullClassCastException - if rhs is not assignment-compatible
with lhsreflectionCompare(Object, Object, boolean, Class))public CompareToBuilder appendSuper(int superCompareTo)
Appends to the builder the compareTo(Object)
result of the superclass.
superCompareTo - result of calling super.compareTo(Object)public CompareToBuilder append(Object lhs, Object rhs)
Appends to the builder the comparison of
two Objects.
lhs == rhslhs or rhs is null,
a null object is less than a non-null objectlhs must either be an array or implement Comparable.
lhs - left-hand objectrhs - right-hand objectClassCastException - if rhs is not assignment-compatible
with lhspublic CompareToBuilder append(Object lhs, Object rhs, Comparator<?> comparator)
Appends to the builder the comparison of
two Objects.
lhs == rhslhs 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 Comparable instead.
lhs - left-hand objectrhs - right-hand objectcomparator - Comparator used to compare the objects,
null means treat lhs as ComparableClassCastException - if rhs is not assignment-compatible
with lhspublic CompareToBuilder append(long lhs, long rhs)
builder the comparison of
two longs.lhs - left-hand valuerhs - right-hand valuepublic CompareToBuilder append(int lhs, int rhs)
builder the comparison of
two ints.lhs - left-hand valuerhs - right-hand valuepublic CompareToBuilder append(short lhs, short rhs)
builder the comparison of
two shorts.lhs - left-hand valuerhs - right-hand valuepublic CompareToBuilder append(char lhs, char rhs)
builder the comparison of
two chars.lhs - left-hand valuerhs - right-hand valuepublic CompareToBuilder append(byte lhs, byte rhs)
builder the comparison of
two bytes.lhs - left-hand valuerhs - right-hand valuepublic CompareToBuilder append(double lhs, double rhs)
Appends to the builder the comparison of
two doubles.
This handles NaNs, Infinities, and -0.0.
It is compatible with the hash code generated by
HashCodeBuilder.
lhs - left-hand valuerhs - right-hand valuepublic CompareToBuilder append(float lhs, float rhs)
Appends to the builder the comparison of
two floats.
This handles NaNs, Infinities, and -0.0.
It is compatible with the hash code generated by
HashCodeBuilder.
lhs - left-hand valuerhs - right-hand valuepublic CompareToBuilder append(boolean lhs, boolean rhs)
builder the comparison of
two booleanss.lhs - left-hand valuerhs - right-hand valuepublic CompareToBuilder append(Object[] lhs, Object[] rhs)
Appends to the builder the deep comparison of
two Object arrays.
==null, null is less than non-nullappend(Object, Object, Comparator)This method will also will be called for the top level of multi-dimensional, ragged, and multi-typed arrays.
lhs - left-hand arrayrhs - right-hand arrayClassCastException - if rhs is not assignment-compatible
with lhspublic CompareToBuilder append(Object[] lhs, Object[] rhs, Comparator<?> comparator)
Appends to the builder the deep comparison of
two Object arrays.
==null, null is less than non-nullappend(Object, Object, Comparator)This method will also will be called for the top level of multi-dimensional, ragged, and multi-typed arrays.
lhs - left-hand arrayrhs - right-hand arraycomparator - Comparator to use to compare the array elements,
null means to treat lhs elements as Comparable.ClassCastException - if rhs is not assignment-compatible
with lhspublic CompareToBuilder append(long[] lhs, long[] rhs)
Appends to the builder the deep comparison of
two long arrays.
==null, null is less than non-nullappend(long, long)lhs - left-hand arrayrhs - right-hand arraypublic CompareToBuilder append(int[] lhs, int[] rhs)
Appends to the builder the deep comparison of
two int arrays.
==null, null is less than non-nullappend(int, int)lhs - left-hand arrayrhs - right-hand arraypublic CompareToBuilder append(short[] lhs, short[] rhs)
Appends to the builder the deep comparison of
two short arrays.
==null, null is less than non-nullappend(short, short)lhs - left-hand arrayrhs - right-hand arraypublic CompareToBuilder append(char[] lhs, char[] rhs)
Appends to the builder the deep comparison of
two char arrays.
==null, null is less than non-nullappend(char, char)lhs - left-hand arrayrhs - right-hand arraypublic CompareToBuilder append(byte[] lhs, byte[] rhs)
Appends to the builder the deep comparison of
two byte arrays.
==null, null is less than non-nullappend(byte, byte)lhs - left-hand arrayrhs - right-hand arraypublic CompareToBuilder append(double[] lhs, double[] rhs)
Appends to the builder the deep comparison of
two double arrays.
==null, null is less than non-nullappend(double, double)lhs - left-hand arrayrhs - right-hand arraypublic CompareToBuilder append(float[] lhs, float[] rhs)
Appends to the builder the deep comparison of
two float arrays.
==null, null is less than non-nullappend(float, float)lhs - left-hand arrayrhs - right-hand arraypublic CompareToBuilder append(boolean[] lhs, boolean[] rhs)
Appends to the builder the deep comparison of
two boolean arrays.
==null, null is less than non-nullappend(boolean, boolean)lhs - left-hand arrayrhs - right-hand arraypublic int toComparison()
builder has judged the "left-hand" side
as less than, greater than, or equal to the "right-hand"
side.build()public Integer build()
builder has judged the "left-hand" side
as less than, greater than, or equal to the "right-hand"
side.build in interface Builder<Integer>toComparison()Copyright © 2001–2015 The Apache Software Foundation. All rights reserved.