I have job with regex in my expressions: example !(FA1_A.i & FA1_M.i)

I have operators ! ( ) & |

operands have names [a-zA-Z_]*.[a-zA-Z_]

I wrote in Java to split on tokens, but it doesn't split on operators and operands If should be !, (, FA1_A.i, &, FA1_m.i, ) . Can anybody tell me what is wrong ?

String stringOpеrator = "([!|&()])";
String stringOperand = "(([a-zA-Z_]*)\\.([a-zA-Z_]*))";
String reg=stringOpеrator+"|"+stringOperand;
Pattern pattern = Pattern.compile(reg);

Matcher m = pattern.matcher(expression);
// System.out.println("func: " + function + " item: " + item);
while (m.find()) {
    int a=m.start();
    int b=m.end();
    String test=expression.substring(m.start(), m.end());
    String g=test;
    tokens.add(new Token(expression.substring(m.start() , m.end())));


            //m = pattern.matcher(expression);

        }