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git-svn-id: https://swig.svn.sourceforge.net/svnroot/swig/trunk/SWIG@4142 626c5289-ae23-0410-ae9c-e8d60b6d4f22

1 files changed, 87 insertions, 0 deletions

diff --git a/Examples/java/typemap/example.i b/Examples/java/typemap/example.i
new file mode 100644
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+++ b/Examples/java/typemap/example.i
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+/* File : example.i */
+%module example
+%{
+/*
+   example of a function that returns a value in the char * argument
+   normally used like:
+
+   char buf[bigenough];
+   f1(buf);
+*/
+
+void f1(char *s) {
+  if(s != NULL) {
+    sprintf(s, "hello world");
+  }
+}
+
+void f2(char *s) {
+  f1(s);
+}
+
+void f3(char *s) {
+  f1(s);
+}
+
+%}
+
+/* default behaviour is that of input arg, Java cannot return a value in a 
+ * string argument, so any changes made by f1(char*) will not be seen in the Java
+ * string passed to the f1 function.
+*/
+void f1(char *s);
+
+%include various.i
+
+/* use the BYTE argout typemap to get around this. Changes in the string by 
+ * f2 can be seen in Java. */
+void f2(char *BYTE);
+
+/* alternative approach uses a StringBuffer typemap for argout */
+
+/* what is the corresponding jni type */
+%typemap(jni) char *SBUF "jobject"
+
+/* what types to use in java source code */
+%typemap(jtype) char *SBUF "StringBuffer"
+%typemap(jstype) char *SBUF "StringBuffer"
+
+/* how to convert java type to requested c type */
+%typemap(in) char *SBUF {
+  jclass sbufClass;
+  jmethodID toStringID;
+  jmethodID setLengthID;
+  jstring js;
+
+  $1 = NULL;
+  if($input != NULL) {
+    /* get the String from the StringBuffer */
+    sbufClass = (*jenv)->GetObjectClass(jenv, $input);
+    toStringID = (*jenv)->GetMethodID(jenv, sbufClass, "toString", "()Ljava/lang/String;");
+    js = (jstring) (*jenv)->CallObjectMethod(jenv, $input, toStringID);
+    /* convert the String to a char * */
+    $1 =  (char *)(*jenv)->GetStringUTFChars(jenv, js, 0); 
+    /* zero the original StringBuffer, so we can replace it with the result */
+    setLengthID = (*jenv)->GetMethodID(jenv, sbufClass, "setLength", "(I)V");
+    (*jenv)->CallVoidMethod(jenv, $input, setLengthID, (jint) 0);
+  }
+}
+
+/* how to convert the c type to the java type */
+%typemap(argout) char *SBUF {
+  jclass sbufClass;
+  jmethodID appendStringID;
+
+  if($1 != NULL) {
+    /* append the result to the empty StringBuffer */
+    sbufClass = (*jenv)->GetObjectClass(jenv, $input);
+    appendStringID = (*jenv)->GetMethodID(jenv, sbufClass, "append", "(Ljava/lang/String;)Ljava/lang/StringBuffer;");
+    (*jenv)->CallObjectMethod(jenv, $input, appendStringID, (*jenv)->NewStringUTF(jenv, $1));
+    if($input != NULL) (*jenv)->ReleaseStringUTFChars(jenv, $input, $1);
+  }  
+}
+/* Prevent the default freearg typemap from being used */
+%typemap(freearg) char *SBUF ""
+
+/* apply the new typemap to our function */
+void f3(char *SBUF);