Java Regexs: unexpected char: '('

Question

I am using processing 1.0.6, which runs on java 1.6. I have the following code:

Pattern pattern = Pattern.compile("func\((.*),(\-?[0-9\.]*),(\-?[0-9\.]*),(\-?[0-9\.]*)\)");

but it gives the error:

unexpected char: '('

and highlights the line I pasted above. If I change the offending \( to another character like #, it complains of the \- saying unexpected char: '-'. I should be able to use literals in a regex engine and it works in C#!

Answer 1

You need to escape the backslashes too:

"func\\((.*),(-?[0-9.]*),(-?[0-9.]*),(-?[0-9.]*)\\)"

That string expression will the be evaluated to:

func\((.*),(-?[0-9.]*),(-?[0-9.]*),(-?[0-9.]*)\)

And that’s what you wanted.

Answer 2

You have to escape \ in strings in Java by preceding it with a \, so

Pattern pattern = Pattern.compile("func\\((.*),(\\-?[0-9\\.]*),(\\-?[0-9\\.]*),(\\-?[0-9\\.]*)\\)");

should work.

Answer 3

I think you should replace "\" with "\\"

Pattern pattern = Pattern.compile("func\\((.*),(\\-?[0-9\\.]*),(\\-?[0-9\\.]*),(\\-?[0-9\\.]*)\\)");

Answer 4

In Java '(' and '-' is not an escape-required character. So '(' means '\' without any escape-required character that is why the error occur. The solution to this is the escepe that back-slash too:

Pattern pattern = Pattern.compile("func\\((.*),(\\-?[0-9\\.]*),(\\-?[0-9\\.]*),(\\-?[0-9\\.]*)\\)");

If you need to use RegEx in both Java and C#, perhaps you should write a program that swap from one to another.