ICS 22 Homework 6 Due 11/9

Reminder: we check for cheating (via copying) and all students involved with get a grade of zero for this homework.
(50 points) Write a Java program that will fully test both implementation of a queue. I have partially implemented it for Stacks (although I did not raise exceptions as you should) and I want you to implement it for both Linked Queue and Array Queues.
- Define an abstract class Queue that has the following public abstract operations:
```
void enqueue(Object o);
Object dequeue();
Object next();
boolean isEmpty();
boolean isFull();
String toString();
```
- Derive two concrete classes from class Queue: ArrayQueue and LinkedQueue. The operations will be similar to those you defined for ArrayList and LinkedList from a previous homework. Define only the operations given in the abstract Queue class plus a constructor for each specific kind of stack and the public method toString which allows us to print the contents of your data struture. The constructor for any array-based representation should take an int parameter which is the capacity of the container.
- Write a Java stand-alone application that provides a GUI to test all the operations of either kind of queue. (The interface should work on any kind of Queue.) I want you to create an instance of each kind of stack and test them interactivly by allowing the user to load values from an input TextField.
- I have provided a sample for something similar but for Stacks. You may use a similar form for the programs to test your queue and deque. The start is located off my web page under 22, Homework Starts, under hw6 in the file StackTest.java.
(50 points) Second program: GUI RPN Calculator
- Write a reverse polish notation (RPN) calculator that uses an ArrayStack of doubles. Model it after a real RPN calculator. I'm sure you can find one on the web.
  - The user can enter floating point number via a keypad. The number goes into the display.
  - The calculator should display only the top four numbers of the stack in descending order. For example, the display could look something like this:
```
4:			0
3:			0
2:			0
1:			0
D:			0
```
- D is the display. 1: shows the number at the top of stack, 2: shows the number below the top, and so on. . Here are the operations:
```
  . Enter - pushes the display value onto the top of the stack.
  . "+" - pops the top two numbers, adds them, and pushes the result.
  . "-" - pops the top two numbers, subtracts the top from second from top, and pushes the result.
  . "/" - pops the top two numbers, divides the top into second from top.
  . "*" - pops the top two numbers, multiplies them, and pushes the result.
  . Swap - swaps the top two stack entries.
```