Lambda Expression and Variable Capture

Question

Please explain to me how a lambda expression can use and modify instance variables of its enclosing class, but can only use local variables of its enclosing scope. (Unless i

Answer 1

You can refer this article - https://www.infoq.com/articles/Java-8-Lambdas-A-Peek-Under-the-Hood explained on lambda expressions compilation. As explained lambda expressions/blocks of code are compiled into the anonymous class, these anonymous class are compiled with the name format (<>$<<1(Number)>>), so suppose assume if non final local variables are allowed then compiler cannot trace it from where this local variable is referred as anonymous class' '.class' files are created/compiled with aforementioned format separately like normal java classes.

So if local variable is final then compiler creates a final instance in the anoymous class which doesn't create ambiguity to compiler. Refer the link mention above for more information