de.alpharogroup.evaluate.object.checkers

Class HashcodeCheck

java.lang.Object

de.alpharogroup.evaluate.object.checkers.HashcodeCheck

public final class HashcodeCheck
extends Object

The class HashcodeCheck provides algorithms for check the hashcode contract of an given object.

Constructor Summary

Constructors

Constructor and Description
HashcodeCheck()

Method Summary

Modifier and Type	Method and Description
static <T> Optional<ContractViolation>	consistency(T object) Checks consistency of the given object, that means according to Object.hashCode() that this method should evaluate the following contract condition: Whenever it is invoked on the same object more than once during an execution of a Java application, the hashCode method must consistently return the same integer, provided no information used in equals comparisons on the object is modified.
static <T> Optional<ContractViolation>	equality(T object, T anotherObject) Checks equality of hash code from the given objects that should be equal(if not an IllegalArgumentException will be thrown), that means according to Object.hashCode() that this method should evaluate the following contract condition: If two objects are equal according to the equals(Object) method, then calling the hashCode method on each of the two objects must produce the same integer result.
static <T> Optional<ContractViolation>	unequality(T object, T anotherObject) Checks unequality of hash code from the given objects that should be unequal, that means according to Object.hashCode() that this method should evaluate the following contract condition: It is not required that if two objects are unequal according to the Object.equals(java.lang.Object) method, then calling the hashCode method on each of the two objects must produce distinct integer results.

Methods inherited from class java.lang.Object

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

Constructor Detail

HashcodeCheck

public HashcodeCheck()

Method Detail

consistency

public static <T> Optional<ContractViolation> consistency(T object)

Checks consistency of the given object, that means according to Object.hashCode() that this method should evaluate the following contract condition:

• Whenever it is invoked on the same object more than once during an execution of a Java application, the hashCode method must consistently return the same integer, provided no information used in equals comparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application.

Note: The upper list is taken from the javadoc from Object.hashCode()

Type Parameters:

T - the generic type

Parameters:

object - the object

Returns:

an empty Optional if no violation occurred or an Optional with the specific violation type

equality

public static <T> Optional<ContractViolation> equality(T object,
                                                       T anotherObject)

Checks equality of hash code from the given objects that should be equal(if not an IllegalArgumentException will be thrown), that means according to Object.hashCode() that this method should evaluate the following contract condition:

• If two objects are equal according to the equals(Object) method, then calling the hashCode method on each of the two objects must produce the same integer result.

Type Parameters:

T - the generic type

Parameters:

object - the object

anotherObject - the another object

Returns:

an empty Optional if no violation occurred or an Optional with the specific violation type

unequality

public static <T> Optional<ContractViolation> unequality(T object,
                                                         T anotherObject)

Checks unequality of hash code from the given objects that should be unequal, that means according to Object.hashCode() that this method should evaluate the following contract condition:

• It is not required that if two objects are unequal according to the Object.equals(java.lang.Object) method, then calling the hashCode method on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hash tables.

Type Parameters:

T - the generic type

Parameters:

object - the object

anotherObject - the another object

Returns:

an empty Optional if no violation occurred or an Optional with the specific violation type