LinkedIn File IO We will be building a LinkedIn application throughout the rest of this course. I have created an architecture that I expect you to contribute to. Please read the PDF labeled, The Software Architecture, that is available on the course website for a thorough description of the architecture and how you can contribute to it. To start, download the Eclipse project, java2-lastname-firstname, from the course website and import this project into your Eclipse IDE. Rename the project by supplying your last name and first name to the name of the project. You will be building on to this project week-by-week. Import Instructions 1 - Open Eclipse and select the File -> Import... menu option. 2 - Select the General -> Existing Projects into Workspace option and click the Next button. 3 - Click on the Select archive file option and browse to the Zip file that you downloaded from eLearn. 4 - Click the Finish button to complete the import process. After you import the project you should immediately notice that the project doesn't compile. That's expected at this point. You are going to write the code to make this project compile. The Project This project is made up of two source folders; src and test. Both source folders contain an edu.institution package. The src folder is where you will place source code for the assignment. The test folder is where you will place your unit tests for the assignment. All code for this assignment should be placed in the edu.institution.asn3 package. All of the packages that you will contribute to have been created in this project for you. There is a lib folder which contains all of the supporting JAR files that you will need throughout this course. The lib folder is already added to your class path, so you need not worry about that. Task 1 - Copy Assignment Two To fix some of the compiler errors, copy your code from assignment two into the edu.institution.asn2 package of this project. You only need the source code from the prior assignment. You don't need to copy the unit tests that you wrote in the prior assignment. Task 2 - Implement UserRepository Package: edu.institution The UserRepository interface has been created for you by the architecture. It defines a class which will add, save, remove, and retrieve the user information that we add to our application.

This interface defines the following methods. void init(String filePath, String fileName);

This method should deserialize the data stored at the supplied filePath + fileName location into a list of LinkedIn users. If there is no previously saved data, then this method should initialize a new list of LinkedIn users. Depending on how you implement this method, you may find that the other methods defined on this interface may need access to the supplied filePath, fileName, and to the list of LinkedIn users that is created by this method. If that is the case, then it is recommended that you set these values as properties on the implementing class. See the SerializedUserRepository code snippet below for an example on setting these values as properties of the class. void add(LinkedInUser user) throws LinkedInException;

This method ensures that the supplied user is ready to be added to the user repository and, if so, adds the user to the list of users established from the init method. If the user name and user type are not supplied, throw a new LinkedInException with the message, "The user name and type are required to add a new user." Valid user types are either 'P' for premier or 'S' for standard. If the user type is invalid, throw a new LinkedInException with the message, "Invalid user type. Valid types are P or S." If the supplied user already exists, throw a new LinkedInException with the message, "A user already exists with that user name." If the supplied user is ready to be added, add it to the list and call the saveAll() method to save the data.

void saveAll();

This method overwrites (serializes) the list of LinkedIn users that was established in the init method to the file system. void delete(LinkedInUser user);

This method removes the supplied LinkedIn user from the list of LinkedIn users that was established in the init method. This method should call the saveAll() method to persist the deleted data.

LinkedInUser retrieve(String username);

This method returns the LinkedIn user associated with the supplied user name or null if there is no user associated with the supplied user name. LinkedInUser retrieveAll();

This method returns all LinkedIn users in the repository or an empty list if there are no users in the repository. SerializedUserRepository Package: edu.institution.actions.asn3 You are to create this class and implement the methods described in the UserInterface. Your project should compile cleanly once this class is created and properly implementing the interface.

public class SerializedUserRepository implements UserRepository { @Override public void init(String filePath, String fileName) { // if you need access to these values in any other method on in this class, // then set them as properties of the class this.filePath = filePath; this.fileName = fileName; // deserialize the list of LinkedIn users and set the list as a property of // this class } @Override public void add(LinkedInUser user) throws LinkedInException { } @Override public void delete(LinkedInUser user) { } @Override public List retrieveAll() { return new ArrayList<>(); } @Override public void saveAll() {

} @Override public LinkedInUser retrieve(String username) { return null; } }

Remember: to serialize and de-serialize the LinkedInUser class, it (along with its super class) must implement Serializable. Task 3 - List All Users Menu Action Package: edu.institution.actions.asn3 Class: ListUserAction

public class ListUserAction implements MenuAction { // implement the process method }

This action should retrieve all of the LinkedIn users from the user repository and print each user's user name to the console. The process method for the action should return true to keep the user signed in.

Task 4 - Sign Up a New User Package: edu.institution.actions.asn3 Class: AddUserAction This action should do the following: (Use the supplied Scanner instance to prompt the user for information. Do not create your own instance of Scanner in any action) Prompt the user for the user name to add. prompt the user to enter a password and what type of user he/she is.

To construct a new LinkedInUser, setting the supplied user name, password, and type, and call the add method on the supplied user repository.

If the LinkedInException is thrown, catch it and display the message on from the exception. Return true to keep the user signed in. The process method for the action should return true to keep the user signed in. Task 5 - Delete a User Package: edu.institution.actions.asn3 Class: DeleteUserAction (Use the supplied Scanner instance to prompt the user for information. Do not create your own instance of Scanner in any action) Prompt for the user name to delete. Check if the supplied user name exists in the user list. If the user does NOT exist, display an error message to the console and re-display the menu. If the user does exist, prompt for the password of the user being deleted. If the password is not correct, display an error message to the console and return out of the action. If the password is correct, call the delete method on the user repository passing the user name. If the deleted user was the logged in user, then the action should return false to tell the Application Controller to sign out the current user. Otherwise, return true to keep the user signed in. Task 6 - Sign Off Package: edu.institution.actions.asn3 Class: SignoffAction

This action is easy. Simply return false to tell the Application Controller to sign out the current user.

Answer rating: 100% (QA)

program code to copy DeleteUserACtionjava package eduinstitutionactionsasn3 import javautilScanner import eduinstitutionUserRepository import eduinstitutionactionsMenuAction import eduinstitutionactio... View the full answer