Compile Error: Cannot Find Symbol

Question

I am receiving the error cannot find symbol when the code reaches the recursive call for increment and I have no idea why? Here is the code for increment. Any help will be

Answer 1

String has no method called increment. And of course it isn't a recursive call because you are inside an object(which object? in your code there isn't a class definition) , meanwhile you are invoking increment upon a String object.

In addition your temp field is never used. If you want to share it between method calls you can try something like this:

public void increment (String temp){}

and then pass it while calling it:

String temp = new String(num.substring(0, num.length()-2));
increment(temp);

Of course your function can't work like that. temp parameter should be managed inside your increment method. Review your logic. It's no more a matter of syntax. If you can't change the method signature then declare temp as a field of your BigNatural class:

public class BigNatural {

private String num; 
private String temp
......

and inside increment method simply do:

temp = new String(num.substring(0, num.length()-2));

Answer 2

Some other pointers:

String is an immutable class meaning once it is created it can no longer be changed. So, doing

String t = new String();
t = last.toString();

has now sense since you will create 2 String Objects here (last.toString() will create and return a new String).

Simply do:

String t = last.toString();

or even better:

num.concat(last.toString());

Same goes for temp String, simply do:

String temp = num.substring(0, num.length()-2);

Next, be aware of unintentional autoboxing:

Integer first = 0;
first++;

this will create a new Integer Object every time first++ is executed; Integer (as String) is immutable. When calculating simply use the primitive int instead of Integer.

Finally, be careful that you don't create an infinite loop. If I understand your code num will concatenated to so num.length() > 1 will be true always if it was true the first time.