Data Structures & Algorithmsequals() in the class Objectclass implemen - PDF document

Data Structures & Algorithmsequals() in the class Objectclass implements a public method that returns true iff the two x.equals(y) == trueiff are (references to) the same objectFor some subclasses, this is adequate, especially for types for which the notion of an equality comparison doesn't really make practical sense. Data Structures & AlgorithmsA deeper examination of the issue indicates there are two fundamentally distinct is identical to iff iff , in some useful sense, have equivalent content;For many user-defined types, there are natural definitions of an equality relationship. Data Structures & AlgorithmsGeneral Contract for equals()equivalence relationreflexive: for any non-null reference value : for any non-null reference values -it is : for any non-null reference values , multiple invocations of , provided no information used in equals comparisons on the objects is modified. -for any non-null reference value Data Structures & AlgorithmsA User-defined Class publicclassIt's certainly possible we might create two different record, in which case the notion of equals is different from identity. Data Structures & Algorithms publicclasspublicbooleanreturnfalsereturnfalseWe need to satisfy the general contract: Data Structures & AlgorithmsSpecialized equals() Features publicclasspublicbooleanWe need to implement a sensible definition of what equality means for this type: Data Structures & AlgorithmsComplete Method publicclasspublicbooleanreturnfalsereturnfalse Data Structures & Algorithms publicclass publicinterfacepubliclongpubliclong Object equals()does not know what the actual type is going to be.guarantee a specialized implementation of And so, the tree's search logic will be broken… Data Structures & Algorithms publicinterfacepubliclongpubliclongNow the compiler knows that whatever a And so, the tree's search logic will work… Data Structures & AlgorithmsA Debugging Hint publicclasspublicboolean