External Interfaces/API

Other Data Conversion Topics

There are several remaining items of interest regarding the way MATLAB converts its data to a compatible Java type. This includes how MATLAB matches array dimensions, and how it handles empty matrices and empty strings.

How Array Dimensions Affect Conversion

The term dimension, as used in this section, refers more to the number of subscripts required to address the elements of an array than to its length, width, and height characteristics. For example, a 5-by-1 array is referred to as having one dimension, as its individual elements can be indexed into using only one array subscript.

In converting MATLAB to Java arrays, MATLAB handles dimension in a special manner. For a MATLAB array, dimension can be considered as the number of nonsingleton dimensions in the array. For example, a 10-by-1 array has dimension 1, and a 1-by-1 array has dimension 0. In Java, dimension is determined solely by the number of nested arrays. For example, double[][] has dimension 2, and double has dimension 0.

If the Java array's number of dimensions exactly matches the MATLAB array's number of dimensions n, then the conversion results in a Java array with n dimensions. If the Java array has fewer than n dimensions, the conversion drops singleton dimensions, starting with the first one, until the number of remaining dimensions matches the number of dimensions in the Java array.

Empty Matrices and Nulls

The empty matrix is compatible with any method argument for which NULL is a legal value in Java. The empty string ('') in MATLAB translates into an empty (not NULL) String object in Java.

Passing Java Objects

Passing Data to Overloaded Methods