Fixes for StringBuffer typemap example

git-svn-id: https://swig.svn.sourceforge.net/svnroot/swig/trunk/SWIG@4393 626c5289-ae23-0410-ae9c-e8d60b6d4f22

1 files changed, 38 insertions, 24 deletions

diff --git a/Examples/java/typemap/example.i b/Examples/java/typemap/example.i
index d50ddc4cc..a29c717d9 100644
--- a/Examples/java/typemap/example.i
+++ b/Examples/java/typemap/example.i
@@ -37,51 +37,65 @@ void f1(char *s);
  * 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 */
+/* Alternative approach uses a StringBuffer typemap for argout */
+
+/* Define the types to use in the generated JNI C code and Java code */
+%typemap(jni) char *SBUF "jobject"
 %typemap(jtype) char *SBUF "StringBuffer"
 %typemap(jstype) char *SBUF "StringBuffer"
 
-/* how to convert java type to requested c type */
+/* How to convert Java(JNI) 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 */
+    /* Get the String from the StringBuffer */
+    jmethodID setLengthID;
+    jclass sbufClass = (*jenv)->GetObjectClass(jenv, $input);
+    jmethodID toStringID = (*jenv)->GetMethodID(jenv, sbufClass, "toString", "()Ljava/lang/String;");
+    jstring js = (jstring) (*jenv)->CallObjectMethod(jenv, $input, toStringID);
+
+    /* Convert the String to a C string */
+    const char *pCharStr = (*jenv)->GetStringUTFChars(jenv, js, 0);
+
+    /* Take a copy of the C string as the typemap is for a non const C string */
+    jmethodID capacityID = (*jenv)->GetMethodID(jenv, sbufClass, "capacity", "()I");
+    jint capacity = (jint) (*jenv)->CallObjectMethod(jenv, $input, capacityID);
+    $1 = (char *) malloc(capacity+1);
+    strcpy($1, pCharStr);
+
+    /* Release the UTF string we obtained with GetStringUTFChars */
+    (*jenv)->ReleaseStringUTFChars(jenv,  js, pCharStr);
+
+    /* 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 */
+/* How to convert the C type to the Java(JNI) 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);
+    /* Append the result to the empty StringBuffer */
+    jstring newString = (*jenv)->NewStringUTF(jenv, $1);
+    jclass sbufClass = (*jenv)->GetObjectClass(jenv, $input);
+    jmethodID appendStringID = (*jenv)->GetMethodID(jenv, sbufClass, "append", "(Ljava/lang/String;)Ljava/lang/StringBuffer;");
+    (*jenv)->CallObjectMethod(jenv, $input, appendStringID, newString);
+
+    /* Clean up the string object, no longer needed */
+    free($1);
+    $1 = NULL;
   }  
 }
 /* Prevent the default freearg typemap from being used */
 %typemap(freearg) char *SBUF ""
 
+/* Convert the jstype to jtype typemap type */
+%typemap(javain) char *SBUF "$javainput"
+
 /* apply the new typemap to our function */
 void f3(char *SBUF);
+