6.4 Working with Variables in Lambdas

Question 1

📝️ What are the different variables exists in a Lambda expression?

Answer 1

• > Parameter list variables
• > Local variables inside the lambda body
• > External variables referenced from the lambda body

Question 2

📝️ What are the lambda’s parameter variables rules?

Answer 2

o The parameter type is optional
o You can even use var in place of the specific type
o Single parameter (without type) does NOT require parentheses
🤯️⚠️📣️ When declaring parameter type/var use parentheses

• > Predicate p = x -> true;
• > Predicate p = (String x) -> true;
• > Predicate p = (var x) -> true;

Question 3

📝️ What are the lambda’s local variables inside the body rules?

Answer 3

• > You can’t redeclare an existent variable on param-list / external variable referenced
• > Watch out Missed ‘;’ semi-colon at the end;

Question 4

📝️ What are the lambda’s external variable rules?

Answer 4

• > Class/Instance variables are always allowed.

- > Method parameters and local variables are allowed to be referenced if they are 💥️effectively final💥️