Large Java arrays and their applications

All current implementations of Java Virtual Machines allow the creation of one-dimensional arrays of length smaller than 2³¹ elements. In addition, since Java lacks true multidimensional arrays, most of numerical libraries use one-dimensional arrays to store multidimensional data. With the current limitation, it is not possible to store volumes of size larger than 1290³. On the other hand, the data from scientific simulations or medical scanners continuously grow in size and it is not uncommon to go beyond that limit. This work addresses the problem of maximal size of one-dimensional Java arrays. JLargeArrays is a Java library of one-dimensional arrays that can store up to 2⁶³ elements. Performance comparison with native Java arrays and Fastutil library shows that JLargeArrays is the fastest solution overall. Possible applications in Java collections as well as numerical and visualization frameworks are also discussed.