We have a problem with converting a C char buffer in a jstring. We are using the JNI function NewStringUTF to convert a char buffer, that contains character like äöü and so on, in a jstring. The conversion of the äöü results in a sign like ?.

Alon Ziv

It is quite likely your string is not in UTF8, but in a locale-specific encoding (e.g. ISO8859-1). You need to first convert it into UTF8 or UCS2/Unicode (using e.g. iconv [on Unix] or MultiByteToWideChar [Win32]), and then JNI functions will accept it gladly.