It seems this won't work in java according to Google. But I have no programming background, so perhaps someone could give a definitive answer with regard to nested functions. I did manage to make a working example via nested classes. Whatever works is my new mantra

Code Example:

1. void setup() {
2.   size(300,300);
3.   background(153);
4.   showA myShowA = new showA(5);
5. }
6. 
   
7. class showA {
8.   int a;
9.  
10.   showA(int a) {
11.     this.a = a;
12.     showA1 myShowA1 = new showA1();
13.     showA2 myShowA2 = new showA2();
14.   }
15. 
    
16.   class showA1 {
17.     showA1() {
18.       print("[1." + a + "] ");
19.     }
20.   }
21. 
    
22.   class showA2 {
23.     showA2() {
24.       print("[2." + a + "] ");
25.     }
26.   }
27. }

Perhaps you should explain why you want to be able to do this; then we might be able to suggest an approach that works.  For instance you could use an object to store the variables.  Then you'd only need to pass the object as a parameter to your functions; or better still write a method that does what you want internally...

Definitive answer: no, it won't work (unlike many other programming languages, indeed).
If you need to share variables between two functions, the best way is as blindfish suggested, to put both functions in a class and make these variables to be fields of the class. That's the classical way in Java.