public void putOperator(String op) {
while (operators.size() > 0
&& precedence(operators.get(operators.size() - 1)) >= precedence(op)) {
reduce();
}
operators.add(op);
}
public void put(String elem) {
if (elem.equals("(")) {
operators.add(elem);
} else if (elem.equals(")")) {
while (!operators.get(operators.size() - 1).equals("(")) {
reduce();
}
operators.remove(operators.size() - 1);
} else if (elem.matches("\\d+")) {
putNumber(elem);
} else {
putOperator(elem);
}
}
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);
}
