The RandomAccess Interface - Java

The RandomAccess Interface

The RandomAccess interface contains no members. However, by implementing this interface, a collection signals that it supports efficient random access to its elements. Although a collection might support random access, it might not do so efficiently. By checking for the RandomAccess interface, client code can determine at run time whether a collection is suitable for certain types of random access operations—especially as they apply to large collections. (You can use instanceof to determine if a class implements an interface.) RandomAccess is implemented by ArrayList and by the legacy Vector class, among others.