CODEWITHSUNDEEP
javainterfacequeue
Deepak sai
Deepak sai

Reputation: 79

java Queue Interface

I am looking in to the java queue and i stuck in this line "Queue implementations generally do not define element-based versions of the equals and hashCode methods but instead inherit the identity-based versions from Object."

1.need the complete meaning of the above text.
2.what is element based versions of the equals and hashcode -- what it refers to ?
3.Identity based versions -- what does this mean ?
4. is Version belong to class or object / who's version and where it will be ?

URL :https://docs.oracle.com/javase/tutorial/collections/interfaces/queue.html

Upvotes: 2

Views: 541

Answers (1)

Eran
Eran

Reputation: 394106

It means that standard implementations of the Queue interface usually don't override equals and hashCode methods of the Object class, which means the default implementation of Object class is used (i.e. the identity-based version which simply uses == for equals).

Element based versions of equals and hashCode would determine if two Collections are equal and calculate hashCode based on the elements contained in the Collection, which is why it is called "Element based".

For example, ArrayList (or actually its super-class AbstractList) overrides equals in a way that two Lists are equal to each other if they have the same number of elements and the elements are equal to each other (in the order in which they appear). The hashCode is a function of the hashCodes of all the elements.

Upvotes: 4

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