The ArrarList class is in the clollection API （applictation programming interface), whick is a library provided by Java.Most of the API in java.util . This library gives the programmer access to prepackaged data staructures and the methods to manipulate them . The implementations of these container classes are invisible and should not be of concren to the programmer . The code works . And it is reusable .
All of the collections classes ,including ArrayList , hava thefollowing features int commons:
- They are designed to be both memory and run-time efficient.
- They provide methods for insertion and removal of items (i.e., they can grow and shrink).
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They provide for iteration over the entire collection