FAQ-0277 How do I convert between Java strings and Unicode descriptors?


FAQ-0277 How do I convert between Java strings and Unicode descriptors?

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Classification:	Java	Category:	JNI
Created:	09/23/99	Modified:	07/03/2001
Number:	FAQ-0277
Platform:	Not Applicable

Question:
How do I convert between Java strings and Unicode descriptors?

Answer:
To get a TPtrC from a Java string (received in a JNI context as a jstring), you can use the following code:
JNIEXPORT jint JNICALL Java_Example__1native(JNIEnv* aJNI, jclass, jstring aString)

{
const jchar* const ptr = aJNI->GetStringChars(aString, NULL);
const jsize len = aJNI->GetStringLength(aString);
TPtrC16 ptr16(ptr, len);
jint error = NativeStuff(ptr16); // must not modify data!
aJNI->ReleaseStringChars(aString, ptr); // original data no longer needed
return error;
}
To get a jstring (which can be returned to the Java side) from a TPtrC16 (or TBufC16) descriptor, you can use the following code:

TPtrC16 buf;
...
jstring str = aJNI->NewString(buf.Ptr(), buf.Length());
Similarly for an HBufC16 heap descriptor:

HBufC16* buf;
...
jstring str = aJNI->NewString(buf->Ptr(), buf->Length())

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