Question

Remaining Time: 1 hour, 59 minutes, 35 seconds. Question Completion Status: What is the primary difference between a Set and a Map? T T T Arial , J (12p?. T . :-·-·?·ees Path p QUESTION 54 Explain briefly the operation of each of the tollowing Iterator-related methods a) iterator b) hasNext c) next Click Save and Submit to save and submit.Ciek Save Al Ansers to save all ansvers

Answer 1

Difference between Set and Map

If we want to represent a group of objects as single entity where duplicates are not allowed and insertion order is not preserved then we should prefer Set

In set it allows at most one single value

If we don’t want to allow duplicates in the database then we should go for Set

If we want to represent a group of objects as key value pairs then we should go for Map.Where Map doesn’t allow duplicate keys but duplicate values are allowed.

Map allow at most one null value as key and any number of null as values

In Map ,insertion order is not preserved.

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iterator():

If we call this method on the collection class(Ex: ArrayList) then we will get an Iterator class.Which is used to iterate over the ArayList.

Ex:

ArrayList<Integer> arl=new ArrayList<Integer>();

Iterator it=arl.iterator();

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hasNext():

We call this method on the Iterator class to check whether it has next element or not.If it has next element it will return true,otherwise it will return false.

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next() :

This method is used to get the next element .If we have next element it returns that element ,otherwise it throws NoSuchElementException.

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