Manufacturer OO RequestHomepage  « Case Study « Manufacturer OO Request

The stakeholder Stocking Goods Limited have also requested that we create a class representing the record information within the Manufacturer file called unsurprisingly Manufacturer as they see a lot of future reuse of this file and it will also be helpful when implementing the Stock interface. In this lesson we create the Manufacturerclass, wherein a Manufacturer object is a representation of the Manufacturer file in an object oriented framework, allowing easy access to fields.

We will be creating a log file using the java.util.Logger class which allows us to put messages into a file that we can view after a run of the application to help with debugging and to store information about events that have occurred and methods that have been invoked. We can also set the granularity of log messages when we need finer or less detailed information to appear in our log files. We will create log files in most of our other top level classes so that we can see the general flow through our coding if problems arise.

Access to the methods of the Manufacturer class can be invoked remotely and so this object can be serialized, therefore we use a version number so that serialisation can occur without worrying about the underlying class changing between serialisation and deserialisation.

We will use statics for the length of each field within the Manufacturer file and private instance variables that can be accessed by public getters and setters.

A default no arguments constructor will be coded as well as a constructor to set initial values for a Manufacturer object.

We will also override the equals(), hashCode() and toString() methods of the Object class.

Another point of interest not covered elsewhere on the site are the annotation used for the Logger, @SuppressWarnings("unused") which supresses compiler warnings for a field not being used and the Object class overrides using @Override which ensures we override correctly and informs browsers of the code that this is an override. Annotations were introduced in Java5 and are a form of metadata that provide data about a program but are not part of the program itself and have no direct effect on the operation of the code annotated.

Compiling The Manufacturer Classgo to top of page Top

Cut and paste the following code into your text editor and save it in the   c:\_Case_Study\src\model directory.


package model;

import java.util.logging.Logger;

/**
 * A Manufacturer object is a representation of the Manufacturer file
 * in an object oriented framework, allowing easy access to fields.
 * 
 * @author Kevin 
 * @version 1.0
 * @see model.StockImpl
 *
 */
public class Manufacturer {
    /**
     * The Logger instance through which all log messages from this class are routed.
     * Logger namespace is s2cCaseStudy.
     */
    private static Logger log = Logger.getLogger("s2cCaseStudy"); // Log output

    /**
     * A version number for the Manufacturer class so that serialisation 
     * can occur without worrying about the underlying class changing 
     * between serialisation and deserialisation.
     */
    @SuppressWarnings("unused")
	private static final long serialVersionUID = 871964L;

    /* Declared constants for lengths of each field in the Manufacturer record. */
    /**
     * Length of Manufacturer deletedFlag field.
     */
    static final int DELETED_FLAG_LENGTH = 1;

    /**
     * Length of Manufacturer name field.
     */
    static final int NAME_LENGTH = 30;

    /**
     * Length of Manufacturer location field.
     */
    static final int LOCATION_LENGTH = 30;

    /**
     * Length of Manufacturer Product field.
     */
    static final int PRODUCT_LENGTH = 40;

    /**
     * Length of Manufacturer price field.
     */
    static final int PRICE_LENGTH = 8;

    /**
     * Length of Manufacturer stockLevel field.
     */
    static final int STOCK_LEVEL_LENGTH = 3;

    /**
     * Length of Manufacturer stockOrdered field.
     */
    static final int STOCK_ORDERED_LENGTH = 3;
    
    /**
     * Length of a complete Manufacturer data record, calculated 
     * by adding all the fields together. 
     */
    public static final int MANUFACTURER_RECORD_LENGTH = DELETED_FLAG_LENGTH
                               	                       + NAME_LENGTH
                               	                       + LOCATION_LENGTH
                               	                       + PRODUCT_LENGTH
                              	                       + PRICE_LENGTH
                               	                       + STOCK_LEVEL_LENGTH
                              	                       + STOCK_ORDERED_LENGTH;
    
    /* Instance variables. */
    /**
     * Stores the Deleted flag.
     */
    private String deletedFlag = ""; 	// The deleted flag indicator.

    /**
     * Stores the name of the Manufacturer 
     */
    private String name = ""; 			// Manufacturer Name.

    /**
     * Stores the City Location of the Manufacturer.
     */
    private String location = ""; 		// Manufacturer Location.

    /**
     * Stores the product name.
     */
    private String product = "";	    // Product name.

    /**
     * Stores the unit price of the product.
     */
    private String price = ""; 			// Product unit price.

    /**
     * Stores the amount of stock available.
     */
    private String stockLevel = ""; 	// Product available from manufacturer.

    /**
     * Stores the amount of stock ordered.
     */
    private String stockOrdered = ""; 	// Amount of product ordered.

    /* Manufacturer constructors. */
    /**
     * Create an instance of Constructor with default values.
     */
    public Manufacturer() {
        log.entering("Manufacturer", "Manufacturer");
        log.exiting("Manufacturer", "Manufacturer");
    }

    /**
     * Create an instance of Constructor with a list
     * of initial values.
     * 
     * @param deletedFlag The Deleted flag value.
     * @param name The name of the Manufacturer.
     * @param location The City Location of the Manufacturer.
     * @param product Product name.
     * @param price Product unit price.
     * @param stockLevel Amount of product available from manufacturer.
     * @param stockOrdered Amount of product ordered.
     */
     public Manufacturer(String deletedFlag, String name, String location, 
			String product, String price, String stockLevel, String stockOrdered) {
        log.entering("Manufacturer", "Manufacturer", new Object[]{name, location,
	    		product, price, stockLevel, stockOrdered});
        this.deletedFlag = deletedFlag;
        this.name = name;
        this.location = location;
        this.product = product;
        this.price = price;
        this.stockLevel = stockLevel;
        this.stockOrdered = stockOrdered;
        log.exiting("Manufacturer", "Manufacturer");
    }

    /* Manufacturer getter and setter methods. */
    /**
     * Returns the value of the Deleted Flag.
     * 
	 * @return A String containing the deleted flag value.
     */
    public String getDeletedFlag() {
        log.entering("Manufacturer", "getDeletedFlag");
        log.exiting("Manufacturer", "getDeletedFlag", this.deletedFlag);
        return deletedFlag;
    }

    /**
     * Sets the deleted flag value
     * 
     * @param deletedFlag A String containing the 
     * deleted flag value.
     */
    public void setDeletedFlag(String deletedFlag) {
        log.entering("Manufacturer", "setDeletedFlag");
        this.deletedFlag = deletedFlag;
        log.exiting("Manufacturer", "setDeletedFlag", this.deletedFlag);
    }

    /**
     * Returns the value of the manufacturer name.
     * 
     * @return A String containing the name of the manufacturer.
     */
    public String getName() {
        log.entering("Manufacturer", "getName");
        log.exiting("Manufacturer", "getName", this.name);
        return name;
    }

    /**
     * Sets the manufacturer name value
     * 
     * @param name A String containing the name of the manufacturer.
     */
    public void setName(String name) {
        log.entering("Manufacturer", "setName");
        this.name = name;
        log.exiting("Manufacturer", "setName", this.name);
    }

    /**
     * Returns the value of the manufacturer location.
     * 
     * @return A String containing  the manufacturer location.
     */
    public String getLocation() {
        log.entering("Manufacturer", "getLocation");
        log.exiting("Manufacturer", "getLocation", this.location);
        return location;
    }

    /**
     * Sets the manufacturer location value.
     * 
     * @param location A String containing  the manufacturer location.
     */
    public void setLocation(String location) {
        log.entering("Manufacturer", "setLocation");
        this.location = location;
        log.exiting("Manufacturer", "setLocation", this.location);
    }

    /**
     * Returns the name of the product. 
     *  
     * @return product A String of name of the product.
     */
    public String getProduct() {
        log.entering("Manufacturer", "getProduct");
        log.exiting("Manufacturer", "getProduct", this.product);
        return product;
    }

    /**
     * Sets the types of work performed value.  
     * 	  
     * @param product A single String of name of the product.
     */
    public void setProduct(String product) {
        log.entering("Manufacturer", "setProduct");
        this.product = product;
        log.exiting("Manufacturer", "setProduct", this.product);
    }
	  
    /**
     * Returns the unit price of a product. 
     * 
     * @return price A String containing price of a product. 
     */
    public String getPrice() {
        log.entering("Manufacturer", "getPrice");
        log.exiting("Manufacturer", "getPrice", this.price);
        return price;
    }

    /**
     * Sets the unit price of a product.
     * 
     * @param price A String containing price of a product.
     */
    public void setPrice(String price) {
        log.entering("Manufacturer", "setPrice");
        this.price = price;
        log.exiting("Manufacturer", "setPrice", this.price);
    }

    /**
     * Returns the stock level of a product.
     * 
     * @return stockLevel A String containing product stock level.
     */
    public String getStockLevel() {
        log.entering("Manufacturer", "getStockLevel");
        log.exiting("Manufacturer", "getStockLevel", this.stockLevel);
        return stockLevel;
    }

    /**
     * Sets the stock level of a product.
     * 
     * @param stockLevel A String containing stock level.
     */
    public void setStockLevel(String stockLevel) {
        log.entering("Manufacturer", "setStockLevel");
        this.stockLevel = stockLevel;
        log.exiting("Manufacturer", "setStockLevel", this.stockLevel);
    }

    /**
     * Returns the amount of stock on order.
     * 
     * @return stockOrdered A String containing stock on order.
     */
    public String getStockOrdered() {
        log.entering("Manufacturer", "getStockOrdered");
        log.exiting("Manufacturer", "getStockOrdered", this.stockOrdered);
        return stockOrdered;
    }

    /**
	 * Sets the amount of stock on order.
     * 
     * @param stockOrdered A String containing stock on order.
    */
    public void setStockOrdered(String stockOrdered) {
        log.entering("Manufacturer", "setStockOrdered");
        this.stockOrdered = stockOrdered;
        log.exiting("Manufacturer", "setStockOrdered", this.stockOrdered);
    }

    /* override Object methods equals(), hashCode() and toString(). */
    /**
     * Checks whether two Manufacturer objects are the same by
     * comparing their name and manufacturer fields.
     * 
     * @param obj The Manufacturer to compare with this Manufacturer
     * @return true If this Manufacturer and other manufacturer have 
     * same name and location. 
     */
    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
		
        if (!(obj instanceof Manufacturer))
            return false;

        Manufacturer other = (Manufacturer) obj;

        if (location == null) {
            if (other.location != null)
                return false;
        } else if (!location.equals(other.location))
            return false;
		
        if (name == null) {
            if (other.name != null)
                return false;
        } else if (!name.equals(other.name))
            return false;
		
        return true;
    }

    /**
     * Returns a hashCode for this Manufacturer object using name and location
     * fields. Although this may not return unique hashCodes it should ensure
     * the objects are spread fairly evenly across the buckets.
     *
     * @return hashKey An int hashCode for this Manufacturer instance.
     */
    @Override
    public int hashCode() {
        log.entering("Manufacturer", "hashCode");

        String hashKey = name + location;
        log.exiting("Manufacturer", "hashCode", hashKey.hashCode());
        return hashKey.hashCode();
    }

    /**
     * A String representation of the Manufacturer class.
     *
     * @return A String representation of the Manufacturer class.
     */
    @Override
    public String toString() {
        log.entering("Manufacturer", "toString");
        String strVal = "["
                      	+ this.deletedFlag + "; "
                      	+ this.name + "; "
                      	+ this.location + "; "
                      	+ this.product + "; "
                      	+ this.price + "; "
                      	+ this.stockLevel + "; "
                      	+ this.stockOrdered
                      	+ "]";

        log.exiting("Manufacturer", "toString", strVal);
        return strVal;
    }
}

Compiling Our Source File With the -cp and -d Options

Open your command line editor:

Change to directory  cd c:\_Case_Study\src\model

Compile Manufacturer.java using the java compiler with the -cp and -d options
  javac -cp ..\..\classes -d ..\..\classes Manufacturer.java

Compiling The ManufacturerFileAccessException Classgo to top of page Top

Reading files is risky and so we wrap file access calls in try.. catch blocks to catch any I/O exceptions that may occur. For the case study whenever we access the Manufacturer file we have to code for a possible exception. So we will need to make a new exception to cater for I/O exceptions when trying to access the Manufacturer file, which we will call ManufacturerFileAccessException.

Cut and paste the following code into your text editor and save it in the   c:\_Case_Study\src\model directory.


package model;

/**
 * Holds any data access exceptions that may occur in the Manufacturer file.
 * 
 * @author Kevin 
 * @version 1.0
 * @see StockImpl
 *
 */
public class ManufacturerFileAccessException extends RuntimeException {

    /**
     * A version number for the ManufacturerFileAccessException class so that serialisation 
     * can occur without worrying about the underlying class changing 
     * between serialisation and deserialisation.
     * 
     */
    private static final long serialVersionUID = 871964L;

    /**
     * Create a default ManufacturerFileAccessException instance.
     * 
     */
    public ManufacturerFileAccessException() {
        super();
    }

    /**
     * Create a ManufacturerFileAccessException instance that accepts a String.
     * 
     * @param e The string description of the exception.
     */
    public ManufacturerFileAccessException(String e) {
        super(e);
    }

    /**
     * Create a ManufacturerFileAccessException instance and chain an exception.
     * 
     * @param e The exception to wrap
     */
    public ManufacturerFileAccessException(Throwable e) {
        super(e);
    }
}

Compiling Our Source File With the -cp and -d Options

Open your command line editor:

Change to directory  cd c:\_Case_Study\src\model

Compile ManufacturerFileAccessException.java using the java compiler with the -cp and -d options
  javac -cp ..\..\classes -d ..\..\classes ManufacturerFileAccessException.java

The following screenshot shows that we now get a clean compile and also the Manufacturer and ManufacturerFileAccessException classes are now compiled into the classes\model directory.

compile Manufacturer class

Related Java6 Tutorials

Objects & Classes - Class Structure and Syntax
Objects & Classes - Reference Variables
Objects & Classes - Methods
Objects & Classes - Instance Variables & Scope
Objects & Classes - Constructors
Objects & Classes - Static Members
OO Concepts - Encapsulation - Getters & Setters
OO Concepts - The Object Superclass - Checking Object Equality
OO Concepts - The Object Superclass - The hashCode() Method
OO Concepts - The Object Superclass - The toString() Method
Flow Control - Handling Exceptions
Flow Control - Declaring Exceptions
Flow Control - Creating Our Own Exceptions
Swing - RMI - Serialization


What's Next?

In our final lesson of the section we implement the Stock interface using the StockImpl class and create some method stubs we will come back, to when we revisit the model code in the Model Part 2 section.

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