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Order of different collection type in java?

开发者 https://www.devze.com 2023-03-26 13:08 出处:网络
Just wanted to confirm the in what order we get the elements from different collection List ArrayList:- the sequence in which we put the element we get them in same sequence

Just wanted to confirm the in what order we get the elements from different collection

List

ArrayList:- the sequence in which we put the element we get them in same sequence

LinkedList:- when we add an element in linked list with add(E e) it will be added at last when we get it with itertator it will start from first element to last element. So we can say the sequence in which we put the element we get them in reverse sequence

Set

HashSet:- No sequence(for getting the elemnets) is guaranted. It will be a random sequence

Tresset:- Will get the elements as per their natural ordering or compara开发者_JAVA百科tor defined at the time of creation

Map

HashMap:- No sequence(for getting the elemnets) is guaranted. It will be a random sequence

TreeMap:- Will get the elements as per their natural ordering of key or comparator defined at the time of creation

Please let me know if it is correct?


Yup - apart from your use of the word random. The order from a hash set/map won't actually be random; it will just be implementation-specific and unpredicatable. Not quite the same thing - in particular, you shouldn't use it as a source of randomness - but you're right that you shouldn't rely on it being any specific ordering.


This ordering is what you would get if you used an iterator. I think the Java Doc are clear enough for this to be apparent. Mind you this is not all on one page.

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