MATLAB BUILDER JA 2 Uživatelská příručka stáhnout pdf (Strana 72)

3 Programming

heap, MWArray objects should be explicitly freed as soon as possible by the

application that creates them.

Using the dispose Method

The best technique for freeing resources for classes created by MATLAB

Builder for Java is to call the

dispose method explic itly. Any Java object,

including an

MWArray object, has a dispose method.

The

MWArray classes also have a finalize method, called a finalizer, that

calls

dispose. Although you can think of the MWArray finalizer as a kind of

safety net f or the cases when you do not call

dispose explicitly, keep in mind

that you cannot determine exactly when JVM calls the finalizer, and the JVM

might not discover memory that should be freed.

Code Fragment: Using dispose

The following example allocates an approx imate 8 MB native array. To

theJVM,thesizeofthewrappedobjectisjustafewbytes(thesizeofan

MWNumericArray instance) and thus not of significant size to trigger the

garbage collector. This example shows why it is good practice to free the

MWArray explicitly.

/* Allocate a huge array */

int[] dims = {1000, 1000};

MWNumericArray a = MWNumericArray.newInstance(dims,

MWClassID.DOUBLE, MWComplexity.REAL);

. (use the array)

/* Dispose of native resources */

a.dispose();

/* Make it eligible for garbage collection */

a = null;

The statement a.dispose() frees the memory allocated by both the managed

wrapper and the native MATLAB array.

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MATLAB BUILDER JA 2 Uživatelská příručka Strana 72