22.7. Scope and Access

Try these first

1. 1.

   What does it mean for a variable to be effectively final?

   Hint

   Think about how the variable is used in a lambda.

2. 2.

   Can you use a variable that is modified after its declaration inside a lambda?

   Hint

   Consider the definition of effectively final.

3. 3.

   What is an effectively final variable?

   • A variable that can change after declaration
   • A variable never modified after assignment
   • Any declared variable

   Hint

   Reflect on the term 'effectively'.

4. 4.

   Can a lambda modify local variables in its enclosing scope?

   • True
   • False

   Hint

   Think about the rules that restrict what lambdas can access.

5. 5.

   Create a Java program that uses a lambda to sum the values of an array while trying to modify a local counter inside the lambda. What errors arise?

   Hint

   Check what happens to any counter variable if you try to redefine it in the lambda.

6. 6.

   Illustrate with code how an effectively final variable can be used in a sorting lambda while clarifying why a non-final variable cannot be used.

   Hint

   Experiment with creating two different versions of the same functionality.