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Practice Object Interaction

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Explanation: Checking Out and Returning Books

1:24 with Ashley Boucher

For the next step in our library application, let's start discussing how patrons can check out and return books.

Instructions for Workspace

Your instructions are as follows:

1) Inside the Book class, add three properties to the constructor method: out, dueDate, and patron.

  • The out property should be initialized to false
  • The dueDate property should be initialized to null
  • The patron property should be initialized to null

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    Now that we've written the methods for the library class, we can start thinking about 0:00
    how to implement the methods in our patron class, check out and return book. 0:04
    Our rough plan didn't have any methods for the book class, so for 0:08
    now we don't have to worry about that. 0:11
    As we know from our experience with real-life libraries, 0:13
    a patron has the ability to check out a book. 0:16
    We need to write a method on our patron class that models this activity. 0:19
    Our check out method has to do something to indicate that the patron 0:23
    has checked out a book. 0:26
    One obvious way to do this is to set the patrons currentBook property 0:28
    to the book object representing the book that's being checked out. 0:31
    Setting the currentBook property can be done in the checkout method. 0:35
    Having this property is great because the library employee can see what book 0:39
    any given patron has checked out at any time. 0:43
    But wait a second. 0:46
    This doesn't seem like enough to me. 0:47
    Shouldn't this information go two ways? 0:49
    I think a library employee should be able to look up any book object, 0:52
    see if it's been checked out, and who checked it out and see when it's due. 0:56
    This is where we have to both expand on a rough plan and 1:01
    go on a little bit of a coding tangent. 1:03
    Information like whether a book has been checked out, who checked it out and 1:06
    when it's due should probably be properties on the book class, right? 1:09
    Let us go back and add those. 1:13
    Open up the attached work space to find an updated read me and 1:15
    follow the instructions. 1:18
    There is a summary of what we discussed in this video in the following 1:20
    instruction step. 1:22

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