About Question enthuware.ocpjp.i.v11.2.3069 :

[girishankaran]

Compiler is not accepting var in (var a, var b)

ls.sort((var a, var b) -> a.compareTo(b));
It is working without var

[admin]

It compiles fine. Check your Java version.

[raphaelzintec]

yes i agree i learned var cannot be method param type but didnt know lambda accept