Split string and calculate power of the 2 substrings

Question

My input string looks like this "10^-9" . Since Java don't handle exponentiation and "^" stands for bitwise XOR, I tried to do it differently. I splitted the String in 10 and -9 and parsed it into double, then used Math.pow() to get the value of it. The code looks like this:

String[] relFactorA = vA.getValue().split("^"); //vA.getValue is a String like `"10^-9"` or any other number instead of 9.
Double pow1 = Double.parseDouble(relFactorA[0]);
Double pow2 = Double.parseDouble(relFactorA[1]);
Double relFactor = Math.pow(pow1, pow2);
System.out.println(relFactor);

But that approach results in an java.lang.NumberFormatException. In the code I cannot find an error, whether I did something wrong or the compiler recognizes the "-(Minus)" as a "-(hyphen)", but I dont think thats the reason, because both Strings look the same and the compiler should see this.

Answer 1

You probably didn't split on ^ since split uses regex as parameter and in regex ^ has special meaning (its start of line). To make it literal use "\\\\^" .

Answer 2

String.split() uses a regex as parameter. If you want to split for the symbol ^ use \\\\^ instead.

String[] relFactorA = vA.getValue().split("\\^");

Answer 3

Note that String#split takes a regex and not a String:

public String[] split(String regex )

You should escape the special character ^ :

vA.getValue().split("\\\\^");

Escaping a regex is usually done by \\ , but in Java, \\ is represented as \\\\ .

Instead, you can use Pattern#quote that will treat the ^ as the String ^ and not the meta-character ^ :

Returns a literal pattern String for the specified String.

vA.getValue().split(Patter.quote("^"));