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Thread: How to draw a class diagram

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    Question How to draw a class diagram

    I'm new to Object-Oriented Programming. I really don't understand how to draw a class diagram exactly. This is my problem.

    Based on the following description, draw a class diagram of an information system for a company called North Marina. The company offers docking spots for the boats. Boat owners rent docking spots based on an annual agreement for each boat, which can be renewed. An owner can have several boats, however each boat is assigned a unique docking spot stated in the agreement. North Marina also offers boat repair service which requires an owner to sign a contract with a company representative responsible for repair. In your class diagram, model the relationships between the classes: DOCKING SPOT, BOAT, AGREEMENT, OWNER, CONTRACT and REPRESENTATIVE.

    I drew this class diagram but I'm not sure if it's right. Could everyone help me to check and fix it. Thanks a lot.
    Capture10-9-2013-9.32.02 PM.jpg


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    Default Re: How to draw a class diagram

    Might be in your interest to use a basic UML diagram maker. The first I ever tried was Violet . It might be worth trying out.
    Please use [highlight=Java]//code goes here...[/highlight] tags when posting your code

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    Default Re: How to draw a class diagram

    Thank for your program but I need someone check my solution. Did I determine the relationships between the classes and their multiplicities (1,*) correctly?

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    Default Re: How to draw a class diagram

    I'm not sure about the multiplicities. That was never my strength.
    From a design point of view, I might consider rearranging the bottom row to reduce the amount of line crossing, but that is based purely preference.
    I do get tripped up by this part though:
    North Marina also offers boat repair service which requires an owner to sign a contract with a company representative responsible for repair.
    The details are a bit vague. Does the owner have any direct relationship with the representative (your diagram suggests no, and I sort of agree based on the lack of information)? But, more concerning, would the contract have some reference to either boat or agreement? I mean, a boat repair contract isn't very useful if there is no mention of what boat is being repaired...

    I think, as is, your diagram is fine (unless someone says the multiplicities are wrong). I assume this is for school. If your professor takes off points because s/he intended on contract doing any of what I said, you should argue that the instructions were vague.
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    Default Re: How to draw a class diagram

    Draw any Flow diagram such as business diagrams/chart, organizational charts, network diagrams, mind maps, building plans, fashion designs, workflows, electrical engineering diagrams etc. Use a third party Edraw tool if you want good and professional result.
    Last edited by tapy; June 12th, 2014 at 04:32 AM.

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    Default Re: How to draw a class diagram

    Just as an general hint that i have been given back in the day, when ever you meet A*---*B relationship ( many to many ), you should immediately consider splitting it up. You can draw like that but implementing it that way would be hard. The usual way is to break it down with an association (or link or cross-reference) class.

    Many-to-many (data model) - Wikipedia, the free encyclopedia

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