public String inToPost() {
for (int i = 0; i < input.length(); i++) {
char ch = input.charAt(i);
switch (ch) {
case '+':
case '-':
gotOperator(ch, 1);
break;
case '*':
case '/':
gotOperator(ch, 2);
break;
case '(':
s.push(ch);
break;
case ')':
gotParenthesis();
break;
default:
output = output + ch;
}
}
while (!s.isEmpty()) output = output + s.pop();
return output;
}
private void gotParenthesis() {
while (!s.isEmpty()) {
char ch = s.pop();
if (ch == '(') break;
else output = output + ch;
}
}
private void gotOperator(char opThis, int prec1) {
while (!s.isEmpty()) {
char opTop = s.pop();
if (opTop == '(') {
s.push(opTop);
break;
} else {
int prec2;
if (opTop == '+' || opTop == '-') prec2 = 1;
else prec2 = 2;
if (prec2 < prec1) {
s.push(opTop);
break;
} else output = output + opTop;
}
}
s.push(opThis);
}