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Improvements to Java Memory Management docs

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William S Fulton 2017-09-19 20:36:04 +01:00
commit f674018126
1 changed files with 24 additions and 7 deletions
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Doc/Manual/Java.html
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@ -8175,25 +8175,42 @@ public class Container {
</div> </div>
<p> <p>
The following typemaps will generate the desired code. The following typemaps can be used to generate this code:
The 'javain' typemap matches the input parameter type for the <tt>setElement</tt> method and allows adding code after the call.
The 'javacode' typemap simply adds in the specified code into the Java proxy class.
</p> </p>
<div class="code"> <div class="code">
<pre> <pre>
%typemap(javain,
post="elementReference = $javainput;\n"
) Element *e "Element.getCPtr($javainput)"
%typemap(javacode) Container %{ %typemap(javacode) Container %{
// Ensure that the GC doesn't collect any element set from Java // Ensure that the GC doesn't collect any element set from Java
// as the underlying C++ class stores a shallow copy // as the underlying C++ class stores a shallow copy
private Element elementReference; private Element elementReference;
%} %}
%typemap(javain,
post=" elementReference = $javainput;"
) Element *e "Element.getCPtr($javainput)"
</pre> </pre>
</div> </div>
<p>
The 'javacode' typemap simply adds in the specified code into the Java proxy class.
The 'javain' typemap matches the input parameter type and name for the <tt>setElement</tt> method and
the 'post' typemap attribute allows adding code after the JNI call.
The 'post' code is generated into a finally block after the JNI call so the resulting code isn't quite
as mentioned earlier, <tt>setElement</tt> is actually:
</p>
<div class="code">
<pre>
public void setElement(Element e) {
try {
exampleJNI.Container_setElement(swigCPtr, this, Element.getCPtr(e), e);
} finally {
elementReference = e;
}
}
</pre>
</div>
<H3><a name="Java_date_marshalling">25.10.13 Date marshalling using the javain typemap and associated attributes</a></H3> <H3><a name="Java_date_marshalling">25.10.13 Date marshalling using the javain typemap and associated attributes</a></H3>