Why is Array more efficient than flexible-size collection

it is a bit more tricky to understand the two advantges of Array as following:
1. access to items held in an array is often more efficient than access to the items in a comparable flexible-size collection,
2. arrays are able to store objects or primitive -type values, but flexible -size collection can store only object.
thanks in advance

it is a bit more tricky to understand the two
wo advantges of Array as following:
1. access to items held in an array is often more
e efficient than access to the items in a comparable
flexible-size collection,The standard dynamic data structure (with standard I mean member of the collections framework) comparable to the array is the ArrayList. In principle the access to an element is equally efficient in both cases. (There's some overhead because you have to do a method call in the ArrayList case). It's only in very low-level algoritms you need to use arrays. In most cases ArrayList is fine.
2. arrays are able to store objects or primitive
ve -type values, but flexible -size collection can
store only object.This is true with the standard collection, but there are alternative collections that can store primitives, for example,
http://pcj.sourceforge.net/
In the next version of Java there's a new concept call autoboxing. This means there's an implicit conversion taking place between primitive types and their corresponding wrapper class, say between int and Integer. This means you will be able to write your program AS IF you could store primitives in the standard collections.

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StmtText
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Why is Array more efficient than flexible-size collection

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