Java Algorithm for method eval (Data Structures, Chapter 3, Stacks)

1) Create an empty stack of integers.

2) WHILE there are more tokens

3) GET the next token

4) IF the first character of the token is a digit.

5) PUSH the integer onto the stack.

6) ELSE IF the token is an operator

7) POP the right operand off the stack.

8) POP the left operand off the stack.

9) EVALUATE the operation.

10) PUSH the result onto the stack.

11) POP the stack and return the result.