Rules for Data Conversion Between Java and MATLAB

Java to MATLAB Conversion

The following table lists the data conversion rules for converting Java^® data types to MATLAB^® types. The conversion rules apply to scalars, vectors, matrices, and multidimensional arrays of the types listed.

The rules apply not only when calling your own methods, but also when calling constructors and factory methods belonging to the MWArray classes.

Note

When you call an MWArray class method constructor, supplying a specific data type causes the compiler to convert to that type instead of the default.

Java to MATLAB Conversion Rules

Java Type	MATLAB Type
`double`	`double`
`float`	`single`
`byte`	`int8`
`int`	`int32`
`short`	`int16`
`long`	`int64`
`char`	`char`
`boolean`	`logical`
`java.lang.Double`	`double`
`java.lang.Float`	`single`
`java.lang.Byte`	`int8`
`java.lang.Integer`	`int32`
`java.lang.Long`	`int64`
`java.lang.Short`	`int16`
`java.lang.Number`	`double` Note Subclasses of `java.lang.Number` not listed above are converted to `double`.
`java.lang.Boolean`	`logical`
`java.lang.Character`	`char`
`java.lang.String`	`char` Note A Java string is converted to a `1`-by-`N` array of `char` with `N` equal to the length of the input string. An array of Java strings (`String[]`) is converted to an `M`-by-`N` array of `char`, with `M` equal to the number of elements in the input array and `N` equal to the maximum length of any of the strings in the array. Higher dimensional arrays of `String` are converted similarly. In general, an `N`-dimensional array of `String` is converted to an `N+1` dimensional array of `char` with appropriate zero padding where supplied strings have different lengths.

MATLAB to Java Conversion

The following table lists the data conversion rules for converting MATLAB data types to Java types.

Note

The conversion rules apply to scalars, vectors, matrices, and multidimensional arrays of the types listed.

MATLAB to Java Conversion Rules

MATLAB Type	Java Type (Primitive)	Java Type (Object)
`cell`	Not applicable	`Object` Note Cell arrays are constructed and accessed as arrays of `MWArray`.
`structure`	Not applicable	`Object` Note Structure arrays are constructed and accessed as arrays of `MWArray`.
`char`	`char`	`java.lang.Character`
`double`	`double`	`java.lang.Double`
`single`	`float`	`java.lang.Float`
`int8`	`byte`	`java.lang.Byte`
`int16`	`short`	`java.lang.Short`
`int32`	`int`	`java.lang.Integer`
`int64`	`long`	`java.lang.Long`
`uint8`	`byte`	`java.lang.Byte` Java has no unsigned type to represent the `uint8` used in MATLAB. Construction of and access to MATLAB arrays of an unsigned type requires conversion.
`uint16`	`short`	`java.lang.short` Java has no unsigned type to represent the `uint16` used in MATLAB. Construction of and access to MATLAB arrays of an unsigned type requires conversion.
`uint32`	`int`	`java.lang.Integer` Java has no unsigned type to represent the `uint32` used in MATLAB. Construction of and access to MATLAB arrays of an unsigned type requires conversion.
`uint64`	`long`	`java.lang.Long` Java has no unsigned type to represent the `uint64` used in MATLAB. Construction of and access to MATLAB arrays of an unsigned type requires conversion.
`logical`	`boolean`	`java.lang.Boolean`
Function handle	Not supported
Java class	Not supported
User class	Not supported

Unsupported MATLAB Array Types

Java has no unsigned types to represent the uint8, uint16, uint32, and uint64 types used in MATLAB. Construction of and access to MATLAB arrays of an unsigned type requires conversion.