Question

I know pointers don’t exist the way they do in C, but I was wondering if something like this would be possible:

I have 5 global variables, r1 r2 r3 r4 r5, each initially initialized to null

I want to (1) find the variable that hasn’t already been used, (2) assign something to it, and then (3) manipulate that variable later in the program. However, I don’t know the status of the variables until code execution. To make up for this, I now have a bunch of if-else statements:

if(r1==null)
    r1 = [something]    
else if(r2==null)
    r2 = [something]
else if(r3==null)
    r3 = [something]
else if(r4==null)
    r4 = [something]
else if(r5==null)
    r5 = [something]

So far so good. But the problem is, I want to take the variable that was modified in the above code and use/modify that variable later in the program.

So say if r1 and r2 were NOT null, and r3 was null, r3 = [something]. I want to modify r3 later on in the program. In C/C++, I’m thinking I could have set up a pointer to r3 in the if-else statement. Then I could just modify r3 through that pointer later in the program.

Is this possible in Java? Thanks!

EDIT: forgot to mention, r1-r5 are Strings.

Answer 1

For something this simple, you could use an array.
You can keep an array index as pointer to the variable you want.

String[] r = new String[5]; // all nulls

and so:

private int findFirstNull(String[] array) {
  for(int i=0; i<r.length; i++)
    if(r[i] == null)
      return i;
  return -1;
}