Supporting Multidimensional Arrays in Java

The lack of direct support for multidimensional arrays in Java TM has been recognized as a major deficiency in the language’s applicability to numerical computing. It has been shown that, when augmented with multidimensional arrays, Java can achieve very high-performance for numerical computing through the use of compiler techniques and efficient implementations of aggregate array operations. Three approaches have been discussed in the literature for extending Java with support for Multidimensional arrays: class libraries that implement these structures; relying on the JVM to recognize those arrays of arrays that are being used to simulate multidimensional arrays; and extending the Java language with new syntactic constructs for multidimensional arrays and directly compiling those constructs to byte-code. This paper presents a balanced presentation of the pros and cons of each technique in the areas of functionality, language and virtual machine impact, implementation effort, and effect on performance. We show that the best choice depends on the relative importance attached to the different metrics, and thereby provide a common ground for a rational discussion of the technique that is in the best interests of the Java community at large, and the growing community of numerical Java programmers.