myhw3.data

Class Data

java.lang.Object

myhw3.data.Data

public class Data
extends java.lang.Object

A static class for accessing data objects.

Constructor Summary

Constructors

Modifier	Constructor and Description
private	Data()

Method Summary

Modifier and Type	Method and Description
static Command	newAddCmd(Inventory inventory, Video video, int change) Returns a command to add or remove copies of a video from the inventory.
static Command	newClearCmd(Inventory inventory) Returns a command to remove all records from the inventory.
static Command	newInCmd(Inventory inventory, Video video) Returns a command to check in a video.
static Inventory	newInventory() Returns a new Inventory.
static Command	newOutCmd(Inventory inventory, Video video) Returns a command to check out a video.
static Video	newVideo(java.lang.String title, int year, java.lang.String director) Factory method for Video objects.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Data

private Data()

Method Detail

newInventory

public static final Inventory newInventory()

Returns a new Inventory.

newVideo

public static Video newVideo(java.lang.String title,
                             int year,
                             java.lang.String director)

Factory method for Video objects. Title and director are "trimmed" to remove leading and final space.

Throws:

java.lang.IllegalArgumentException - if Video invariant violated.

newAddCmd

public static Command newAddCmd(Inventory inventory,
                                Video video,
                                int change)

Returns a command to add or remove copies of a video from the inventory.

The returned command has the following behavior:

• If a video record is not already present (and change is positive), a record is created.
• If a record is already present, numOwned is modified using change.
• If change brings the number of copies to be less than one, the record is removed from the inventory.

Parameters:

video - the video to be added.

change - the number of copies to add (or remove if negative).

Throws:

java.lang.IllegalArgumentException - if inventory not created by a call to newInventory.

newOutCmd

public static Command newOutCmd(Inventory inventory,
                                Video video)

Returns a command to check out a video.

Parameters:

video - the video to be checked out.

newInCmd

public static Command newInCmd(Inventory inventory,
                               Video video)

Returns a command to check in a video.

Parameters:

video - the video to be checked in.

newClearCmd

public static Command newClearCmd(Inventory inventory)

Returns a command to remove all records from the inventory.