The problem is that Rule.output()
expects three int parameters, but what you're calling it with on the line
next_string += rule.output(0, prev_string.charAt(0), prev_string.charAt(1));
is actually an int and then 2 chars. Now, the actual character is '0', but due to the implicit conversion the language does for you, you get the ASCII code of '0', which is 48 and that's what's passed to the function Rule.output()
.
Now, to fix this problem you need to use the method Character.getNumericValue()
like so:
next_string += rule.output(0, Character.getNumericValue(prev_string.charAt(0)), Character.getNumericValue(prev_string.charAt(1)));
Don't forget to change the other two invocations of Rule.output()
However, note that this is not the only problem in your code, as I'm still getting String index out of range: 7
, because the parameters with which the Rule.output()
method is called with are now all 0, but I've answered your original question. If you need more help, let me know.