com.wantedtech.common.xpresso.helpers

Class CompareTo

java.lang.Object

com.wantedtech.common.xpresso.helpers.CompareTo

public class CompareTo
extends java.lang.Object

Assists in implementing Comparable.compareTo(Object) methods.

Two Objects that compare equal using equals(Object) should normally also compare equal using compareTo(Object).

To use this class write code as follows:

 public class MyClass {
   String field1;
   int field2;
   boolean field3;//do not use in the comparison

   ...

   public int compareTo(Object o) {
     MyClass myClass = (MyClass) o;
     return new CompareTo(this, o, "field1", "field2").getComparison();
   }
 }
 

Values are compared in the order they are given to the constructor. In the example above the values in the "field1" will be compared first, the the values in the "field2".

Since:

0.1

See Also:

Comparable, Object.equals(Object), Object.hashCode(), Equals, HashCode

Constructor Summary

Constructors

Constructor and Description
CompareTo(java.lang.Object lhs, java.lang.Object rhs, java.lang.String field0, java.lang.String... moreFields) Constructor for CompareTo.

Method Summary

Modifier and Type	Method and Description
int	append(boolean[] lhs, boolean[] rhs, java.lang.String fieldName) Appends to the fieldComparisons the deep comparison of two boolean arrays.
int	append(boolean lhs, boolean rhs, java.lang.String fieldName) Appends to the builder the comparison of two booleanss.
int	append(byte[] lhs, byte[] rhs, java.lang.String fieldName) Appends to the fieldComparisons the deep comparison of two byte arrays.
int	append(byte lhs, byte rhs, java.lang.String fieldName) Appends to the fieldComparisons the comparison of two bytes.
int	append(char[] lhs, char[] rhs, java.lang.String fieldName) Appends to the fieldComparisons the deep comparison of two char arrays.
int	append(char lhs, char rhs, java.lang.String fieldName) Appends to the fieldComparisons the comparison of two chars.
int	append(double[] lhs, double[] rhs, java.lang.String fieldName) Appends to the fieldComparisons the deep comparison of two double arrays.
int	append(double lhs, double rhs, java.lang.String fieldName) Appends to the fieldComparisons the comparison of two doubles.
int	append(float[] lhs, float[] rhs, java.lang.String fieldName) Appends to the fieldComparisons the deep comparison of two float arrays.
int	append(float lhs, float rhs, java.lang.String fieldName) Appends to the fieldComparisons the comparison of two floats.
int	append(int[] lhs, int[] rhs, java.lang.String fieldName) Appends to the fieldComparisons the deep comparison of two int arrays.
int	append(int lhs, int rhs, java.lang.String fieldName) Appends to the fieldComparisons the comparison of two ints.
int	append(long[] lhs, long[] rhs, java.lang.String fieldName) Appends to the fieldComparisons the deep comparison of two long arrays.
int	append(long lhs, long rhs, java.lang.String fieldName) Appends to the fieldComparisons the comparison of two longs.
int	append(java.lang.Object[] lhs, java.lang.Object[] rhs, java.util.Comparator<?> comparator, java.lang.String fieldName) Appends to the fieldComparisons the deep comparison of two Object arrays.
int	append(java.lang.Object[] lhs, java.lang.Object[] rhs, java.lang.String fieldName) Appends to the fieldComparisons the deep comparison of two Object arrays.
int	append(java.lang.Object lhs, java.lang.Object rhs, java.util.Comparator<?> comparator, java.lang.String fieldName) Appends to the fieldComparisons the resultat of comparison of two Objects for the given field fieldName.
int	append(java.lang.Object lhs, java.lang.Object rhs, java.lang.String fieldName) Appends to the fieldComparisons the result of comparison of two Objects for a given field name,
int	append(short[] lhs, short[] rhs, java.lang.String fieldName) Appends to the fieldComparisons the deep comparison of two short arrays.
int	append(short lhs, short rhs, java.lang.String fieldName) Appends to the fieldComparisons the comparison of two shorts.
int	getComparison() 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.
void	reflectionCompare() Compares two Objects via reflection.

Methods inherited from class java.lang.Object

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

Constructor Detail

CompareTo

public CompareTo(java.lang.Object lhs,
                 java.lang.Object rhs,
                 java.lang.String field0,
                 java.lang.String... moreFields)

Constructor for CompareTo.

Parameters:

lhs - left-hand object

rhs - right-hand object

field0 - including

moreFields

are fields to compare in the given order

moreFields - including

field0

are fields to compare in the given order

Method Detail

reflectionCompare

public void reflectionCompare()

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.

• Static fields will not be compared
• Compares also superclass fields for all superclasses (if those fields are given to the constructor).

If both lhs and rhs are null, they are considered equal.

Throws:

java.lang.NullPointerException - if either lhs or rhs (but not both) is null

java.lang.ClassCastException - if rhs is not assignment-compatible with lhs

append

public int append(java.lang.Object lhs,
                  java.lang.Object rhs,
                  java.lang.String fieldName)

Appends to the fieldComparisons the result of comparison of two Objects for a given field name,

Parameters:

lhs - left-hand object

rhs - right-hand object

fieldName - a field name for the value of which we want to compare the two objects

Returns:

int the result of comparison

Throws:

java.lang.ClassCastException - if rhs is not assignment-compatible with lhs

append

public int append(java.lang.Object lhs,
                  java.lang.Object rhs,
                  java.util.Comparator<?> comparator,
                  java.lang.String fieldName)

Appends to the fieldComparisons the resultat of comparison of two Objects for the given field fieldName.

1. Check if lhs == rhs
2. Check if either lhs or rhs is null, a null object is less than a non-null object
3. Check the object contents

If 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.

Parameters:

lhs - left-hand object

rhs - right-hand object

comparator - Comparator used to compare the objects, null means treat lhs as Comparable

fieldName - field to compare

Returns:

int the result of comprarison

Throws:

java.lang.ClassCastException - if rhs is not assignment-compatible with lhs

append

public int append(long lhs,
                  long rhs,
                  java.lang.String fieldName)

Appends to the fieldComparisons the comparison of two longs.

Parameters:

lhs - left-hand value

rhs - right-hand value

fieldName - a field name for the value of which we want to compare the two objects

Returns:

the result of comparison

append

public int append(int lhs,
                  int rhs,
                  java.lang.String fieldName)

Appends to the fieldComparisons the comparison of two ints.

Parameters:

lhs - left-hand value

rhs - right-hand value

fieldName - a field name for the value of which we want to compare the two objects

Returns:

the result of comparison

append

public int append(short lhs,
                  short rhs,
                  java.lang.String fieldName)

Appends to the fieldComparisons the comparison of two shorts.

Parameters:

lhs - left-hand value

rhs - right-hand value

fieldName - a field name for the value of which we want to compare the two objects

Returns:

the result of comparison

append

public int append(char lhs,
                  char rhs,
                  java.lang.String fieldName)

Appends to the fieldComparisons the comparison of two chars.

Parameters:

lhs - left-hand value

rhs - right-hand value

fieldName - a field name for the value of which we want to compare the two objects

Returns:

the result of comparison

append

public int append(byte lhs,
                  byte rhs,
                  java.lang.String fieldName)

Appends to the fieldComparisons the comparison of two bytes.

Parameters:

lhs - left-hand value

rhs - right-hand value

fieldName - a field name for the value of which we want to compare the two objects

Returns:

the result of comparison

append

public int append(double lhs,
                  double rhs,
                  java.lang.String fieldName)

Appends to the fieldComparisons the comparison of two doubles.

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

fieldName - a field name for the value of which we want to compare the two objects

Returns:

the result of comparison

append

public int append(float lhs,
                  float rhs,
                  java.lang.String fieldName)

Appends to the fieldComparisons the comparison of two floats.

This handles NaNs, Infinities, and -0.0.

Parameters:

lhs - left-hand value

rhs - right-hand value

fieldName - a field name for the value of which we want to compare the two objects

Returns:

the result of comparison

append

public int append(boolean lhs,
                  boolean rhs,
                  java.lang.String fieldName)

Appends to the builder the comparison of two booleanss.

Parameters:

lhs - left-hand value

rhs - right-hand value

fieldName - a field name for the value of which we want to compare the two objects

Returns:

the result of comparison

append

public int append(java.lang.Object[] lhs,
                  java.lang.Object[] rhs,
                  java.lang.String fieldName)

Appends to the fieldComparisons the deep comparison of two Object arrays.

1. Check if arrays are the same using ==
2. Check if for null, null is less than non-null
3. Check array length, a short length array is less than a long length array
4. Check array contents element by element using append(Object, Object, Comparator)

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

fieldName - a field name for the value of which we want to compare the two objects

Returns:

the result of comparison

Throws:

java.lang.ClassCastException - if rhs is not assignment-compatible with lhs

append

public int append(java.lang.Object[] lhs,
                  java.lang.Object[] rhs,
                  java.util.Comparator<?> comparator,
                  java.lang.String fieldName)

Appends to the fieldComparisons the deep comparison of two Object arrays.

1. Check if arrays are the same using ==
2. Check if for null, null is less than non-null
3. Check array length, a short length array is less than a long length array
4. Check array contents element by element using append(Object, Object, Comparator)

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.

fieldName - a field name for the value of which we want to compare the two objects

Returns:

the result of comparison

Throws:

java.lang.ClassCastException - if rhs is not assignment-compatible with lhs

append

public int append(long[] lhs,
                  long[] rhs,
                  java.lang.String fieldName)

Appends to the fieldComparisons the deep comparison of two long arrays.

1. Check if arrays are the same using ==
2. Check if for null, null is less than non-null
3. Check array length, a shorter length array is less than a longer length array
4. Check array contents element by element using append(long, long)

Parameters:

lhs - left-hand array

rhs - right-hand array

fieldName - a field name for the value of which we want to compare the two objects

Returns:

the result of comparison

append

public int append(int[] lhs,
                  int[] rhs,
                  java.lang.String fieldName)

Appends to the fieldComparisons the deep comparison of two int arrays.

1. Check if arrays are the same using ==
2. Check if for null, null is less than non-null
3. Check array length, a shorter length array is less than a longer length array
4. Check array contents element by element using append(int, int)

Parameters:

lhs - left-hand array

rhs - right-hand array

fieldName - a field name for the value of which we want to compare the two objects

Returns:

result of comparison

append

public int append(short[] lhs,
                  short[] rhs,
                  java.lang.String fieldName)

Appends to the fieldComparisons the deep comparison of two short arrays.

1. Check if arrays are the same using ==
2. Check if for null, null is less than non-null
3. Check array length, a shorter length array is less than a longer length array
4. Check array contents element by element using #append(short, short)

Parameters:

lhs - left-hand array

rhs - right-hand array

fieldName - a field name for the value of which we want to compare the two objects

Returns:

result of comparison

append

public int append(char[] lhs,
                  char[] rhs,
                  java.lang.String fieldName)

Appends to the fieldComparisons the deep comparison of two char arrays.

1. Check if arrays are the same using ==
2. Check if for null, null is less than non-null
3. Check array length, a shorter length array is less than a longer length array
4. Check array contents element by element using #append(char, char)

Parameters:

lhs - left-hand array

rhs - right-hand array

fieldName - a field name for the value of which we want to compare the two objects

Returns:

result of comparison

append

public int append(byte[] lhs,
                  byte[] rhs,
                  java.lang.String fieldName)

Appends to the fieldComparisons the deep comparison of two byte arrays.

1. Check if arrays are the same using ==
2. Check if for null, null is less than non-null
3. Check array length, a shorter length array is less than a longer length array
4. Check array contents element by element using #append(byte, byte)

Parameters:

lhs - left-hand array

rhs - right-hand array

fieldName - a field name for the value of which we want to compare the two objects

Returns:

result of comparison

append

public int append(double[] lhs,
                  double[] rhs,
                  java.lang.String fieldName)

Appends to the fieldComparisons the deep comparison of two double arrays.

1. Check if arrays are the same using ==
2. Check if for null, null is less than non-null
3. Check array length, a shorter length array is less than a longer length array
4. Check array contents element by element using #append(double, double)

Parameters:

lhs - left-hand array

rhs - right-hand array

fieldName - a field name for the value of which we want to compare the two objects

Returns:

result of comparison

append

public int append(float[] lhs,
                  float[] rhs,
                  java.lang.String fieldName)

Appends to the fieldComparisons the deep comparison of two float arrays.

1. Check if arrays are the same using ==
2. Check if for null, null is less than non-null
3. Check array length, a shorter length array is less than a longer length array
4. Check array contents element by element using #append(float, float)

Parameters:

lhs - left-hand array

rhs - right-hand array

fieldName - a field name for the value of which we want to compare the two objects

Returns:

the result of comparison

append

public int append(boolean[] lhs,
                  boolean[] rhs,
                  java.lang.String fieldName)

Appends to the fieldComparisons the deep comparison of two boolean arrays.

1. Check if arrays are the same using ==
2. Check if for null, null is less than non-null
3. Check array length, a shorter length array is less than a longer length array
4. Check array contents element by element using append(boolean, boolean)

Parameters:

lhs - left-hand array

rhs - right-hand array

fieldName - a field name for the value of which we want to compare the two objects

Returns:

result of comparison

getComparison

public int getComparison()

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.

Returns:

final comparison result