The unicode value of ucs-4 character '' is 0001f923
, it gets auto changed to the corresponding value of \uD83E\uDD23
when being copied into java code in intelliJ IDEA.
Java only supports ucs-2, so there occurs a transformation from ucs-4 to ucs-2.
I want to know the logic of the transformation, but didn't find any material about it.
https://en.wikipedia.org/wiki/UTF-16#U+010000_to_U+10FFFF
Now with input code point \U1F923:
Programming: