[help]Why can't I use "serial.close()" to close the occupancy of the Serial port?

[Conmi-WhiteJoker]

When the program exits, I use "Serial.close ()".Serial is NULL, but I am still using it until I exit without clearing it.
I found that the serial port was still occupied when I restarted the application.
java.io.IOException: Failed to SET terminal attributes for the serial port. (Error #22)

[Conmi-WhiteJoker]

@PreDestroy private void closeUart() throws Exception { if (!serial.isClosed()) { serial.close(); } }

[luixxx]

Hi Conmi-WhiteJoker,
I can't help, :(
i'm newbie in Pi4j-V2, could you share an example for use of Serial ports?
Thankyou

[FDelporte]

Example has been created on https://pi4j.com/documentation/io-examples/serial/

[savageautomate]

@Conmi-WhiteJoker

The Serial instance is Auto-Closable and should perform a close() on it's own when the Pi4J context is shutdown().

See:
https://github.com/Pi4J/pi4j-v2/blob/32efbf668a9a49fa8e53c55ef23e765180a49aa1/pi4j-core/src/main/java/com/pi4j/io/serial/Serial.java#L39

Also if you are using the PiGPIO library for Serial communication, it appears to also try and ensure the serial is closed on a shutdown.

https://github.com/Pi4J/pi4j-v2/blob/32efbf668a9a49fa8e53c55ef23e765180a49aa1/libraries/pi4j-library-pigpio/src/main/java/com/pi4j/library/pigpio/impl/PiGpioNativeImpl.java#L118-L123

So if the Serial instance is not shutting down properly that would be a problem.
Are you explicitly calling the shutdown() method of the Pi4J context object?

https://github.com/Pi4J/pi4j-example-minimal/blob/5afb12d0388c246f67d5cda8c98a21960f7d2847/src/main/java/com/pi4j/example/MinimalExample.java#L157-L158