toArray

toArray is a common name for a method or function used to convert a collection, iterable, or sequence into an array. It produces a fixed-size array containing all elements in the order produced by the source, and its exact behavior depends on the language and library.

In Java, toArray is defined on the Collection interface with two forms. The no-argument toArray() returns an Object[] containing the elements. The generic toArray(T[] a) returns an array of the specified runtime type T[]. If the provided array is large enough, it is filled and the element immediately after the last is set to null; if it is too small, a new array of the same runtime type is allocated. Java streams provide a variant, toArray(IntFunction<T[]>), which creates a typed array from the stream’s elements using the supplied array constructor.

In C#, the LINQ method Enumerable.ToArray<TSource>(IEnumerable<TSource>) materializes a sequence into a new T[] in iteration order. This is commonly used to cache results or pass a concrete array where an enumerable is expected.

Other languages offer similar utilities. Kotlin collections expose toArray() to obtain an Array<T>, with variations like toTypedArray() for primitive or specialized arrays. In JavaScript, while toArray is not a universal built-in, many libraries provide a toArray function (or use Array.from) to convert iterables or arguments into a standard array.

Considerations when using toArray include performance and memory usage, since the operation creates a new array and copies elements; it generally preserves iteration order and results in an independent, mutable array that does not affect the source collection.