net.sf.mmm.util.lang.api

Interface EqualsChecker<VALUE>

Type Parameters:

VALUE - is the generic type of the values to check.

All Known Implementing Classes:

AbstractEqualsChecker, EqualsCheckerArray, EqualsCheckerCollection, EqualsCheckerIsEqual, EqualsCheckerIsSame

public interface EqualsChecker<VALUE>

This (functional) interface allows to implement an external function to check if two objects are considered as equal independent from the objects equals method. It allows to switch between equals, same or other implementations. Additionally it is null-aware.
ATTENTION:
For specific custom implementations also a corresponding HashCodeFunction has to be provided. Due to lambda support we keep these aspects in separate functional interfaces. Containers that accept an EqualsChecker should also accept a HashCodeFunction for customization. Unfortunately Collections do not allow such customization so you need to wrap objects before using them as

Since:

3.0.0

Author:

Joerg Hohwiller (hohwille at users.sourceforge.net)

Method Summary

Modifier and Type	Method and Description
boolean	isEqual(VALUE value1, VALUE value2) This method determines if the two given objects are equal to each other in a way semantically defined by this implementation.

Method Detail

isEqual

boolean isEqual(VALUE value1,
                VALUE value2)

This method determines if the two given objects are equal to each other in a way semantically defined by this implementation. An implementation must fulfill the contract of the method Object.equals(Object). This means it is:

• reflexive: isEquals(x, x) == true, especially: isEquals(null, null) == true
• symmetric: isEquals(x, y) == isEquals(y, x)
• transitive: (isEquals(x, y) == isEquals(y, z) == true) implies isEquals(x, z)
• consistent: multiple invocations of isEquals(x, y) will always return the same result if x and y are unchanged.
• null-compatible: for all x != null: isEquals(x, null) == isEquals(null, x) == false

Parameters:

value1 - is the first value.

value2 - is the second value.

Returns:

true if both values are null or both are NOT null and equal to each other in the way defined by this EqualsChecker implementation, false otherwise.