@paulgoux , please bring your project ( or MCVE ) to
https://editor.p5js.org/
so we can see the whole thing ( your source? ).
AND also can play.
and the JAVA code please post here again by
pasting it into the
</> code tag
! and test if that what you posted is running ( besides that one error? )
so we easy can copy and try it in processing 3.5.3 JAVA mode
to find your bug.