Homework Assignment #4 Solution

Design and Implement a simple calculator client and a log server.




Requirements: The user should interact with a simple calculator with a Graphical User Interface as follows:









Using this GUI, the user should be able to run the following functions:




R1. At the beginning, the Out Display Panel is empty




R2. The user should be able to conduct simple math calculation by clicking the buttons, and the result should be displayed in the Output Display Panel. Following are some example input and output that should be supported:



Index


Precondition


User action


Post condition


C1




Initialized or reset




The user clicks buttons “3”, “+”,


The system displays “8”,












“5”, and “=” consecutively.


























C2








The user clicks buttons “3”, “3”,










Initialized or reset


“+”, “5”, “5” and “=”


The system displays “88”














consecutively.




















The user clicks buttons “4”, “+”,








C3




Initialized or reset




“5”, “*” (at this point, the system


The system displays “54”.












should display “9”), then clicks “6”






































and “=”








C4


Initialized or reset
The user clicks a non‐digit button


The system remains






unchanged






















C5




Any state




The user clicks “C” bottom




The system resets and














displays nothing






















C6


A non‐digit button is


The user clicks a non‐digit button


The system displays and error




clicked


other than “C”


message with two choices,
































“reset” or “discard”.


C7




Initialized or reset




The user clicks a digit and then




‐‐‐If the user choses “reset”,










clicks “=”




the system reset;






































‐‐‐If the user choses














“discard”, the system is set














back to the previous state


C8
A previous calculation


The user clicks a digit
The system gets ready for a


was successful and the


new calculation














C9


previous result was


The user clicks a non‐digit


The system resets and




displayed




displays nothing


















R3. Whenever a math calculation is successfully conducted, that is, the “=” button is clicked, the client will send a message to the server, which will record the successful math equation, such as “3+5+8=16”




R4. The server should be able to display 1) the total number of all the successful calculated math equations, 2) the list all the equations.




Instructions



You must use a MVC combined with Socket‐based Client‐Server architecture



You must use the following design patterns:



Composite pattern



Visitor Pattern



Observer pattern



State Pattern



You need to turn in the following items from bbLearning:




Submission 1: UML Class diagram




Turn in a *1‐page PDF* UML class diagram showing the design of the calculator client. The diagram has to be generated from a computer program. Do not hand write your UML.




Submission 2: UML Component diagram




Turn in a *1‐page PDF* UML component diagram showing Client component, Server Component, and their interfaces. The diagram has to be generated from a computer program. Do not hand write your UML.




In the component diagram, please make it clear which classes belong to which component. In the client component, please model clearly which classes belong to Model, View and Controller, which should be the inner components within Client.




Submission 3: source code in a Java project




Turn in two java projects, one for the server component and another for the client component, which we can open, view the source code, and run the program. You should also include a readme.txt to indicate how to configure and run the program.