12.3. String Parameters
Next, we want to consider how to transfer strings to and from native methods. Strings are quite different in the two languages: In Java they are sequences of UTF-16 code points whereas C strings are null-terminated sequences of bytes. JNI has two sets of functions for manipulating strings: One converts Java strings to “modified UTF-8” byte sequences and another converts them to arrays of UTF-16 values—that is, to
jchar arrays. (The UTF-8, “modified UTF-8,” and UTF-16 formats were discussed in Chapter 1. Recall that the UTF-8 and “modified UTF-8” encodings leave ASCII characters unchanged, but all other Unicode characters are encoded as multibyte sequences.)
The standard UTF-8 encoding and the “modified UTF-8” encoding ...