You must define and implement your own Stack class. The Stackclass supports standard basic stack operations, (like pop(), push()) and you can implement it with an array. You should create a class template–>generic class Stack in Java, but an integer stack would work as well. Set up a function or static method that receives a string representing a postfix expression and it returns an integer result. Your function/method uses a stack to evaluate a postfix expression (see an operand –push; see an operator -pop twice, evaluate, then push result).

Test your function/method and Stack class with the following postfix expressions by using a test driver:

17 2 3 + / 13 –

5 2 3 ^ *

2 3 2 ^ ^

Answers for the postfix expressions above:

-10

40

512