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import java.util.List;
import java.util.LinkedList;
import java.util.ArrayList;
class InfixToPostfix {
static List infixToPostfix(String expression) {
List result = new ArrayList();
LinkedList stackOper = new LinkedList();
for (int i = 0; i < expression.length(); i++) {
char c = expression.charAt(i);
if (precedence(c) > 0) {
while (!stackOper.isEmpty() && precedence(stackOper.peek()) >= precedence(c)) {
result.add(stackOper.pop().toString());
}
stackOper.push(c);
} else if (c == ')') {
char x = stackOper.pop();
while (x != '('){
result.add(Character.toString(x));
x = stackOper.pop();
}
} else if (c == '(') {
stackOper.push(c);
} else {
// character is neither operator nor parentheses
result.add(Character.toString(c));
}
System.out.print(result);
System.out.println(stackOper);
}
while (stackOper.size() > 0) {
result.add(stackOper.pop().toString());
}
return result;
}
private static int precedence(char c) {
switch (c) {
case '+':
case '-':
return 1;
case '*':
case '/':
return 2;
case '^':
return 3;
}
return -1;
}
public static void main(String[] args) {
System.out.println(infixToPostfix("2*((1+1)"));
}
}