Model Part 1 - Stock InterfaceJ8 Home « Model Part 1 - Stock Interface

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In our second lesson of the Model Part 1 section we code up the Stock interface.

Creating The Stock Interface Top

The following Stock interface will be used in other projects and so must be implemented as is. The interface provides the contract for the CRUD operations for the Manufacturer file as well as templates for the search and locking/unlocking mechanisms.

Stocking Goods Limited have also included doc comments for the interface which are written in HTML and can be turned into a document at a later date using the javadoc tool. Stocking Goods Limited have also requested that we provide doc comments for all class, field, constructor and method declarations.

Create the Stock interface in the model package and cut and paste the following code into it.

package model;

/**
 * An interface implemented by classes that provide use of the Manufacturer file.
 * 
 */
public interface Stock {
	
    /**
     * Creates a new record in the Manufacturer file which could be a deleted
     * entry. Inserts the given Manufacturer data, and returns the record
     * number of the new record.
     * 
     * @param manufacturerData An array of Manufacturer data fields.
     * 
     * @return The record number of the Manufacturer record created.
     * @throws DuplicateKeyException Record already exists.
     */
    public long createRecord(String[] manufacturerData) throws DuplicateKeyException;
	

    /**
     * Reads a record from the Manufacturer file and returns a String
     * array where each element is a Manufacturer field value.
     * 
     * @param recNo A record number denoting the byte location in the 
     * Stock file where this Manufacturer record starts.
     * 
     * @return A String array containing the fields of the 
     * Manufacturer record.
     * 
     * @throws RecordNotFoundException Indicates the record was not found.
     */
    public String[] readRecord(long recNo) throws RecordNotFoundException;
	

    /**
     * Modifies the fields of a Manufacturer record. The new value for field n 
     * appears in manufacturerData[n]. Throws a SecurityException if the record 
     * is locked with a number other than lockRecord.
     * 
     * @param recNo The record number of the product record to read.
     * @param manufacturerData A String array of Manufacturer fields.
     * @param lockRecord The lock value.
     * 
     * @throws RecordNotFoundException Indicates the record was not found.
     * @throws SecurityException Indicates a lock record mismatch.
     */
    public void updateRecord(long recNo, String[] manufacturerData, long lockRecord)
    		throws RecordNotFoundException, SecurityException;
	

    /**
     * Deletes a record, making the record number and associated disk storage
     * available for reuse. Throws SecurityException if the record is locked
     * with a number other than lockRecord.
     * 
     * @param recNo The record number of the product record to read.
     * @param lockRecord The lock value.
     * 
     * @throws RecordNotFoundException Indicates the record was not found.
     * @throws SecurityException Indicates a lock record mismatch.
     */
    public void deleteRecord(long recNo, long lockRecord)
    		throws RecordNotFoundException, SecurityException;


    /** 
     * Returns an array of record numbers that match the specified search. Field n 
     * in the Manufacturer file is described by searchCriteria[n]. A null value in 
     * searchCriteria[n] matches any field value. A non-null value in 
     * searchCriteria[n] matches any field value that begins with searchCriteria[n]. 
     *
     * @param searchCriteria The search criteria for retrieving records.
     * 
     * @return A long array of manufacturer record numbers
     * matching the search criteria.
     */
    public long[] findBySearchCriteria(String[] searchCriteria);


    /**
     * Locks a record so that it can only be updated or deleted by this client.
     * Returned value is a number that must be used when the record is unlocked,
     * updated, or deleted. If the specified record is already locked by a
     * different client, the current thread goes into a wait state until the 
     * record is unlocked.
     * 
     * @param recNo The record number of the Manufacturer record to lock.
     * 
     * @return The record number of the locked Manufacturer record.
     * @throws RecordNotFoundException Indicates the record was not found.
     */
    public long lockRecord(long recNo) throws RecordNotFoundException;


    /** Releases the lock on a record. Lock number must be the same as the number
     * returned when the record was locked; otherwise throws SecurityException.
     * 
     * @param recNo The record number of the Manufacturer record to unlock.
     * @param lockRecord The locking number.
     * 
     * @throws SecurityException Indicates a lock record mismatch.
     */
    public void unlock(long recNo, long lockRecord) throws SecurityException;
}

After adding the Stock Interface your project structure should look similar to that in the screenshot below.

Lesson 4 Complete

In this lesson we coded Stock Interface.

Related Java Tutorials

Objects & Classes - Class Structure and Syntax
Objects & Classes - Methods
OO Concepts - Interfaces
Exceptions - Declaring Exceptions - Using the throws Keyword
API Contents - Inheritance - Using the package keyword

What's Next?

In the next lesson we code the manufacturer request class.

• <<    Model Part 1 - Exceptions
• Model Part 1 - Manufacturer Request     >>