Dynamic arrays hold multiple objects and can be resized as needed. They are efficient and fast, but can have memory issues. C++ has a dynamic array class called vector, while Java has Vector, ArrayList, and CopyOnWriteArrayList. Dynamic arrays can be used to organize data and create maintainable code.
A dynamic array is a data structure used in computer programming that holds multiple computation objects as a single group and can be resized at will to accommodate a variable number of objects. The group is contained in a single contiguous block of memory, so accessing elements is efficient and fast. Dynamic arrays are also called vectors or lists, depending on the computer language in which they are used. Despite these names, a particular list or vector may not be a dynamic array, since lists and vectors can be implemented differently from arrays and from each other.
C++ contains a single dynamic array class called vector, which resides in a group of classes called the standard template library. The array backing this class can be accessed via iterators or indexes. Its ability to scale on demand is a big plus, but it can lure programmers into a false sense of security because it’s not as robust as it sounds. Dynamic array backing a vector cannot guarantee that access requests are valid. Like static arrays, dynamic arrays can have bounds-checking and memory corruption problems if a program tries to access memory that hasn’t been allocated for them.
Java contains three distinct dynamic array classes: Vector, ArrayList, and CopyOnWriteArrayList. Items in the array are only accessible by indexes, and attempting to access indexes outside the array typically won’t cause memory corruption issues. The Java Vector class is roughly equivalent to the C++ Vector class and is desynchronized to allow access from multiple threads. ArrayList and CopyOnWriteArrayList, by contrast, are both thread safe. Of the three, CopyOnWriteArrayList is the most labor intensive class, because it completely recreates the dynamic array each time a new value is written to the array.
Dynamic arrays are implemented in essentially the same way regardless of the computer language involved, but depending on a particular language there may be other features built on top of it. Like static arrays, dynamic arrays do not limit the type of object that can be stored in them, as long as they are all of the same object type. A programmer never needs direct access to a dynamic array; it can always be done through a class that wraps the array for easy use. Proper use of these arrays can help a programmer with organizing data within code and also with creating understandable code that lends itself to easy maintenance.
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