Accessing outer class variable in inner class

Question

In inner classes, variables of outer class are accessible, but local variables of a method are not. I understood the part about local variables of a method not being accessible but I want to know why outer class variables are accessible?

My understanding is that as an inner class binds with the outer class, so as long as the parent is available, the child can access its parent variables. Am I correct?

Answer 1

Assuming your outer class is called Outer, from the scope of the inner class(non-static), Outer.this.foo to get at the field.

For example,

Outer.this.foo=new ArrayList<>();

where Outer is the name of the class and foo identifies the field.

You can also grab it directly as foo=new Baz() but it'll pick the inner field if there's a naming conflict due to shadowing.

if it's a static inner class, you need an explicit instance:

outerInstance.foo=new ArrayList<>();

or if the field to access is static, access it as usual with:

Outer.staticFoo=new ArrayList<>();

Answer 2

Answer: Outer class variables in java are accessible because of lexical scope.

What is a lexical scope?

The scope defined in order in which code is authored. Lets say your class structure is as follows

OuterMost  
   --Inner  
     --InnerMost

Then the inner most class will be able to access variables from inner as well outer most.