How convert a binary c string into java String and vice versa?

[kingluo]

For example, I have below c function:

char* get_req(void* handle, int* len);

Then in java:

    public interface FFI {
        Pointer get_req(@In Pointer handle, @Out IntByReference len);
    }
...
    IntByReference ap = new IntByReference();
    var req = ffi.get_req(task, ap);
    var len = ap.intValue();

Here req is a binary string, with len as total length.
Then how to convert req into String for use?

It seems that I could not use req.getString(0), because it assumes the req is null-terminated c string?

[kingluo]

I found a solution:

// from char* pointer to String
final byte[] bytes = new byte[len];
req.get(0, bytes, 0, len);
String str = new String(bytes, StandardCharsets.UTF_8);

// Copy String to pointer
byte[] arr = json.getBytes();
int rspLen = arr.length;
var rspStr = libc.malloc(rspLen);
rspStr.put(0, arr, 0, rspLen);

Is it idiomatic way? If so, why no official doc?