Extracting string from within round brackets in Java with regex

Question

I\'m trying to extract a string from round brackets.
Let\'s say, I have John Doe (123456789) and I want to output the string 123456789 only.

Answer 1

String str="John Doe (123456789)";
System.out.println(str.substring(str.indexOf("(")+1,str.indexOf(")")));

Here I'm performing string operations. I'm not that much familiar with regex.