MATLAB BUILDER JA 2 Podręcznik Użytkownika Pobierz pdf (Strona 53)

Passing Arguments to and from Java

Code Fragment: Passing an MWArray. This example constructs an

MWNumericArray of type MWClassID.DOUBLE.Thecalltomyprimes passes the

number of outputs,

1,andtheMWNumericArray, x:

x = new MWNumericArray(n, MWClassID.DOUBLE);

cls = new myclass();

y = cls.myprimes(1, x);

Java Builder converts the MWNumericArray object to a MATLAB scalar double

to pass to the M-function.

Automatic Conversion to a MATLAB Type

When passing an argument only a small number of times, it is usually just

as eff ici ent to pass a primitiv e Java type or object. In this case, the calling

mechanism converts the data for you into an equivalent MATLAB type.

For instance, e ither of the following Java types w ould be autom atically

converted to the MATLAB

double type:

• AJava

double primitive

• An object of class

java.lang.Double

For reference information about data conversion (tables showing each Java

type along with its converted MATLAB type, and each MATLAB type with its

converted Java type), see “D ata Co nv ersion R ules” o n page 6 -10.

Code Fragment: Automatic Data Conversion

When ca ll ing the makesqr method used in the getmagic application, you could

construct an object of type

MWNumericArray. Doing so would be an example

of manual conversion. Instead, y ou could rely on automatic conversion, as

shown in the following code fragment:

result = M.makesqr(1, arg[0]);

In this case, a Java double is passed as arg[0].

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MATLAB BUILDER JA 2 Podręcznik Użytkownika Strona 53