public int calculate(String expr) {
numbers.clear();
operators.clear();
expr = expr.replaceAll("\\s+", "");
System.out.println(expr);
String[] parts = expr.split("((?=(\\+|\\-|\\*|\\/|\\(|\\)))|(?<=(\\+|\\-|\\*|\\/|\\(|\\))))");
for (String part : parts) {
System.out.print("[" + part + "]");
}
for (String part : parts) {
if (part.length() == 0) {
continue;
}
put(part);
}
while (operators.size() > 0) {
reduce();
}
return numbers.get(0);
}
