I am currently working on a software that makes a serial communication with a hand-made simulator using the RXTX library. To test the limits of my software, I set distinct COM parameters between my 2 programs ; the main software send messages with a baud rate of 9600 and the simulator receives with a baud rate of 19200.
When I try to send the following array: "GET IN_NUM_TRAIN".getBytes() (16 bytes), my simulator receives a byte array containing 27 elements and throws:
INFOS: Traitement du message : ~�``�8���f���f�
java.lang.StringIndexOutOfBoundsException: String index out of range: 26
When I try debugging my code, the received byte array looks like this:

I don't understand why the 8 first values are displayed in red.
The first 8 values are displayed in red to indicate that they have changed.
See Eclipse Help - Java development user guide > Reference > Preferences > Debug Preferences: