The term Java® array refers to a
container object that holds a fixed number of values of a single type.
The type of an array is written as
An array of arrays—also known as a multidimensional array—uses
two or more sets of brackets, such as
The term dimension refers to the number of subscripts required to address the elements of an array. Dimension is not a measure of length, width, and height. For example, a 5-by-1 array is one-dimensional, because you use one subscript to access an individual element. To work with a two-dimensional array, create an array of arrays. To add further dimensions, add more levels to the array, making it an array of arrays of arrays, and so on.
MATLAB® treats multilevel Java arrays like matrices and multidimensional arrays. Use the same MATLAB syntax to access elements of a Java array.
Java array indices are zero-based while MATLAB array
indices are one-based. In Java programming, you access the elements
y of length
When working with this array in MATLAB, you access these elements
For an example, see Access Elements of Java Array.
A two-dimensional MATLAB array is a rectangle, as each row is of equal length and each column of equal height. A Java array is an array of arrays and does not necessarily hold to this rectangular form. Each individual lower level array might have a different length.
The following picture shows an array of three underlying arrays of different lengths. The terms jagged and ragged are commonly used to describe this arrangement of array elements as the array ends do not match up evenly. When a Java method returns a jagged array of primitive Java types, MATLAB stores it in a cell array.
string function pads a
jagged Java string array, making it a rectangular MATLAB array.
size function returns the
length of the Java array. The number of columns is always 1.
The potentially ragged shape of a Java array makes it impossible to size the array in the same way as for a MATLAB array. In a Java array, no single value represents the size of the lower level arrays.
For example, consider the following Java array.
size(A) returns the dimensions of the highest
array level of A. The highest level of the array has a size of 3-by-1.
ans = 3 1
To find the size of a lower level array, for example the five-element array in row 3, refer to the row explicitly.
ans = 5 1
You can specify a dimension in the
using the following syntax. However, this command only sizes the first
dim=1, the only nonunary dimension.
m = size(X,dim) size(A,1)
ans = 3
ndims function always returns
a value of 2 for the number of dimensions in a Java array. This
value is the number of dimensions in the top-level array.