Answer / kumar

Collections are usefull in those situations where you doesn't know how much data you have to handled, that means size of data not defined. Like there are so many scenario when data dynamically comes from UI or application ( no fixed size defined) then you must use collections to manage and perform diff operations.

Answer / suresh

collections are the advanced concept to maintain dynamic data as objects. In real time some times we can't estimate the size of the data and type of the data.so it's better to maintain data as objects through collections.through arrays we can't manage the data because arrays are not auto-grow-able in size.
through collections we can use our required data structures directly. we have different classes for that. in each we have predefined methods to manipulate data in that collection.
Collections are performance wise slow. even though collections provide more features to maintain huge data easily.

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