BBM 104 Programming Assignment 4 – Object-Oriented Programming with Java




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Developing Mini Facebook system via GUI – a prototype1
Graphical User Interfaces, or GUIs, are how users interact with programs. Further, JAVA provides a rich set of libraries
to create Graphical User Interface in a platform independent way. This homework provides a great understanding on
JAVA GUI Programming concepts and after completing this tutorial you will be at an intermediate level of expertise,
from where you can take yourself to higher levels of expertise. In particular, we’ll look at SWING GUI controls along
with Window Builder GUI designer.
As is known, it was aimed to create a mini Facebook system in the previous assignment. In that assignment, you have
utilized the concepts of OOP in order to design and create the required classes. So far, you have developed the logic in
the backend. This time, you will find a chance to create a Graphical User Interface (GUI) based frontend for presenting
an easier to use system. By the end of this assignment, you will have learnt the concepts of Java Swing based GUI
programming as well as adapting the business rules to views.
The learning objective of this programming assignment is to let students practice the following concepts of Java
programming language in particular (and GUI programming in general):
 Object-oriented programming
 Abstraction, Inheritance, Polymorphism
 Abstract Class, Java Interface
 Java Collections
 UML class diagrams
 Developing Graphical User Interfaces (GUI) via Swing components on Window Builder tool.
 Connecting the business rules with views (graphical front ends)

1 Covered subjects: OOP Basics, Abstraction, Encapsulation, Inheritance, Polymorphism, Abstract Class, Interfaces,
Java Collections, UML class diagrams, GUI Programming with Window Builder, Dynamic Control Creation
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The marking scheme is shown below. Carefully review each mark component.
Component Mark %
Creation of Base Classes with the requested class structure (the main class of your
application must be named
Successful instantiation of all initial user objects from the input file 5%
Correct execution of Login and Create User Frames 10%
Correct execution of Profile Page Frame along with dynamic control creation 50%
Correct execution of Tag Friend Frame 10%
Correct execution of Add Post Frame 10%
Drawing of UML class diagram including all JFrame classes (saved as uml.jpg) 5%
Total 100%
Note: In your solutions, your algorithm and code should be as simple as possible.
In this section you can find some useful beginner’s level information that you will need for this project. For more
information on each subject you need to do additional research and consult other resources (e.g. lecture notes, textbook,
Internet resources, etc.).
Java GUI programming involves two packages: the original abstract windows kit (AWT) and the newer Swing toolkit.
Swing introduced a mechanism that allowed the look and feel of every component in an application to be altered
without making substantial changes to the application code. The introduction of support for a pluggable look and feel
allows Swing components to emulate the appearance of native components while still retaining the benefits of platform
independence. Originally distributed as a separately downloadable library, Swing has been included as part of the Java
Standard Edition since release 1.2. The Swing classes and components are contained in the javax.swing package
Swing was developed to provide a more sophisticated set of GUI components than the earlier Abstract Window Toolkit
(AWT). Swing provides a native look and feel that emulates the look and feel of several platforms, and also supports a
pluggable look and feel that allows applications to have a look and feel unrelated to the underlying platform. It has
more powerful and flexible components than AWT. In addition to familiar components such as buttons, check boxes
and labels, Swing provides several advanced components such as tabbed panel, scroll panes, trees, tables, and lists.
Unlike AWT components, Swing components are not implemented by platform-specific code. Instead, they are written
entirely in Java and therefore are platform-independent. The term “lightweight” is used to describe such an element.
Swing components have the prefix J to distinguish them from the original AWT ones (e.g. JFrame instead of Frame). To
include Swing components and methods in your project, you must import the java.awt.*, java.awt.event.*, and
javax.swing.* packages. Displayable frames are top-level containers such as JFrame, JWindows, JDialog, and JApplet,
which interface with the operating system’s window manager. Non-displaying content panes are intermediate
containers such as JPanel, JOptionsPane, JScrollPane, and JSplitPane. Containers are therefore widgets or GUI
controls that are used to hold and group other widgets such as text boxes, check boxes, radio buttons, et al.
Every GUI starts with a window meant to display things. In Swing, there are three types of windows: the Applet, the
Dialog, and the Frame. These interface with the windows manager. In swing, a frame object is called a JFrame. A
JFrame is considered the top most container. These are also called displayable frames. Non-displaying content panes
are intermediate containers such as JPanel, JScrollPane, JLayeredPane, JSplitPane and JTabbedPane which organize
the layout structure when multiple controls are being used. Stated simply, the content pane is where we place out text
fields are other widgets, so to add and display GUI controls, we need to specify that it is the content pane that we are
adding to. The content pane is then at the top of a containment hierarchy, in which this tree-like hierarchy has a top-
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level container (in our case JFrame). Working down the tree, we would find other top level containers like JPanel to
hold the components. The hierarchy of java swing API is given below.
Fig. 1 A short overview of the Swing API
Here is the code that produces a simple frame upon to build on:
public class helloSwing extends JFrame {
private JPanel contentPane;
private JTextField textMass;
private JTextField textHeight;
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
helloSwing frame = new helloSwing();
} catch (Exception e) {e.printStackTrace();}
* Create the frame.
public helloSwing() {
setTitle(“BMI Calculator”);
setBounds(100, 100, 271, 177);
contentPane = new JPanel();
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
JLabel lblNewLabel = new JLabel(“Your mass (kg)”);
lblNewLabel.setBounds(12, 25, 101, 16);
JLabel lblYourHeightm = new JLabel(“Your height (m)”);
lblYourHeightm.setBounds(12, 54, 101, 16);
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textMass = new JTextField();
textMass.setBounds(111, 25, 116, 22);
JButton btnCalculateBMI = new JButton(“Calculate BMI”);
btnCalculateBMI.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
double mass = Double.parseDouble(textMass.getText());
double height = Double.parseDouble(textHeight.getText());
double BMI = mass / Math.pow(height, 2);
JOptionPane.showMessageDialog(null, “Your BMI is: ” + BMI);
btnCalculateBMI.setBounds(111, 93, 116, 25);
textHeight = new JTextField();
textHeight.setBounds(111, 57, 116, 22);
A GUI builder is a visual programming tool that lets a user build a graphical user interface by dragging and dropping
elements from a palette onto a design surface. GUI builders typically contain Wizards and templates that help automate
the GUI building process. GUI building tools allow developers to spend less time and money creating Java GUIs,
because they can focus on creating application-specific functionality rather than coding the low-level logic required for
GUIs to run.
According to Ben Galbraith, in his Successful GUI Building blog, “In my experience, the number one reason why GUI
builders hold appeal is that they often lead to an order of magnitude improvement in productivity over hand coding,
especially amongst average-level Swing developers. I consider myself above average, and I see improvements in
productivity around 2x-10x (perhaps higher) in my own work.”
Created in 2003 by Instantiations, WindowBuilder is widely regarded as the best GUI builder in the Java world (winning
the award for Best Commercial Eclipse Tool in 2009). Beyond being an exemplary example of a GUI design tool for
SWT, XWT, Swing and Google’s GWT, WindowBuilder is also a highly extensible and customizable framework (with
50+ existing extension points) for creating new GUI design tools based on any UI toolkit for any language. Google relaunched WindowBuilder as a free product available to any member of the Eclipse community soon after its acquisition
of Instantiations in 2010, and now wishes to contribute the framework (the WindowBuilder Engine) and associated
products (SWT Designer and Swing Designer) to the Eclipse Foundation. Google will continue to invest heavily in the
project, as it will continue to be the basis for its own in-house GWT Designer tool.
WindowBuilder is composed of SWT Designer and Swing Designer and makes it very easy to create Java GUI
applications without spending a lot of time writing code. Use the WYSIWYG visual designer and layout tools to create
simple forms to complex windows; the Java code will be generated for you. Easily add controls using drag-and-drop,
add event handlers to your controls, change various properties of controls using a property editor, internationalize your
app and much more.
WindowBuilder is built as a plug-in to Eclipse and the various Eclipse-based IDEs (RAD, RSA, MyEclipse, JBuilder,
etc.). The plug-in builds an abstract syntax tree (AST) to navigate the source code and uses GEF to display and manage
the visual presentation.
Generated code doesn’t require any additional custom libraries to compile and run: all of the generated code can be
used without having WindowBuilder Pro installed. WindowBuilder Pro can read and write almost any format and
reverse-engineer most hand-written Java GUI code. It also supports free-form code editing (make changes
anywhere…not just in special areas) and most user re-factorings (you can move, rename and subdivide methods without
a problem). WindowBuilder toolkit can be easily download from Help menu of Eclipse by searching in marketplace.
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Fig. 2 A screenshot of the WindowBuilder
In this programming assignment, you will develop a very simplified version of Facebook, well-known social media
platform. We will call it Mini-Facebook. Note that Programming Assignments 3 and 4 are consecutive and you can use
your classes which you have already created in Assignment 3 with few modifications.
In this assignment you are supposed to create a GUI based front end by using Swing components. By using this GUI, a
user must interact with your Mini-Facebook system.
First, you will be supplied with two text files (“users.txt” and “commands.txt”) which you will use them to initialize
the system. To be precise, all users, their friendship/blocked users lists will be built by use of these two input files.
Moreover, all the initial posts will be created and assigned to related users. You can get the name of these files from
args parameter in static main function. Their names and order will be users.txt and commands.txt respectively.
In this assignment, the user class and business logic of the system have been changed a bit. In the following list, these
changes have been listed
1. In this assignment it is enabled all users to login by providing his/her username and password whereas the
rd assignment focuses on single user login. Note that, to let another user login, the previously logged in user
must log out first. This is because your system is capable of handling only one active logged in user.
2. User class now contains a new property “relationship_status” which is designed to store one of the following
values {“In a relationship”, “Divorced”, “Complicated”, “Single”}.
3. The userid property of the User class is no longer needed since username field is a unique value property.
Therefore, you can use username property as a key in collections.
4. Some functions (e.g. change password) of the User class have been removed. Please read the Section 3.1.1 for
new rules of User class.
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5. In the 3rd assignment, there was a requirement of the UserCollection class which states “Displaying users’
posts”. However, within this assignment, the responsibility of the Posts has been moved to User class itself. In
other words, some functions such as “add post” or “show post(s)” will be handled by User class since Posts of
the user must be stored in a collection at User class.
Note that, user collection class still exists and it is responsible for storing each user in its collection. In the following sub
sections the details of the business classes are presented.
3.1.1 Users
Users are people who have an account on our Mini-Facebook system. Users will not have different roles (e.g. admin or
system manager vs. other users); that is, they will all be peers. User’s attributes and behaviors are explained below:
 Every User in the system has a unique username, a name, a password, a date of birth, information about school
from which the user graduated, a last log-in date, a collection of friends, a collection of blocked users, and a
collection of posts.
 Users’ dates of birth and last log-in dates should be stored as Date or Calendar variable. However both the
input and GUI rendering format must be “dd/mm/yyyy” (e.g. 03/11/1997)
 All collections must be implemented as Java Collections.
 Users must be able to
o Sign in,
o Sign out,
o Update their user profile info (name, date of birth, school graduated and relationship status),
o Add friends to their friend lists,
o Remove friends from their friend lists,
o Add posts,
o Block users,
o Unblock users,
o List their friends,
o List all available users (here the term available is used to refer the users that you did not block and the users
that you have not been blocked by them),
o List blocked users.
 When a user is not logged-in, he/she should be allowed only to perform a sign-in. After user log-in, other
actions should be permitted.
 Note that you are required to hide sensitive personal user info and implement setter and getter methods as
3.1.2 Posts
Posts represent textual or multimedia content shared by users. You are expected to design your post classes in a
hierarchical structure. The necessary information about posts is as follows:
 First of all, you need to implement an interface which will specify behavior (methods) that the Post class will
 Secondly, you need to implement an abstract Post class which will implement the post interface and be a
superclass to all other post classes.
 This abstract Post class should define post attributes, implement the methods defined in the interface, and
define two additional abstract methods that will show tagged users and show post location. These methods
should be implemented in the immediate subclasses of the Post class.
 Posts are categorized as either TextPosts, ImagePosts, or VideoPosts. But be careful: all posts have a textual
part (all posts are actually text posts), and can optionally contain image or video (but not both!).
 All posts have a unique postID which should be assigned as a random UUID (immutable universally unique
identifier), a text, a date when the post originated, a location, and a collection of tagged friends.
 Location should be implemented as a separate class with the following attributes: latitude and longitude
(stored as double values).
 TextPost class should implement abstract methods from the abstract Post class. To show the tagged friends, it
is enough to print their names (if any). To show the post location, both latitude and longitude should be printed.
 ImagePosts have the image filename, and the image resolution (width and height in pixels).
 VideoPosts have the video filename, video duration, and a constant attribute that specifies the maximum
video length in minutes (the maximum allowed video duration is 10 minutes).
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 Note that you are required to implement setter and getter methods as necessary.
3.1.3 User Collection
The main class of UserCollection needs to allow for the following actions:
 Keeping track of all users,
 Adding new users to the system (by providing new user information),
 Removing existing users from the system (by providing the username),
 User sign-in (with username and password),
 In the 3rd assignment, there was a requirement which states “Displaying users’ posts”. However, the
responsibility of Posts has been moved to User class itself.
3.1.4 System Initialization
By using “users.txt” and “commands.txt” you should initialize the system. The command structure and details are
presented in the following lines. Further, you will neither generate a warning nor an output during the initialization
stage since the commands will be error-free and do not contain any Turkish character. As you may realize, the number
of commands in the input files have been reduced to 5 because of moving to GUI environment.
 Adding New Users (user.txt): At the initial stage, your program should retrieve the user information from the
file users.txt and add them to the system. Syntax of the command is as provided below. Every line starts with
the name of the user.
Usage Illustration:
Adnan Yukseladnanadnan101/01/1991ODTUSingle
 Creation of Friendship (commands.txt): In this command, you build a friendship between two users. As a
result, two users add each other as a friend Syntax of the command is as provided below.
Usage Illustration:
 Blocking the Users (commands.txt): In most of the real world social platforms, a user might want to block
another user due to several reasons (disturbing posts, etc.). In this assignment, your implementation should
also allow users to block other users given a username as the argument. As a result of this command, two users
should block each other. In real world, blocking operation is one directional. However, in this assignment,
blocking operation has been defined as bi-directional for the sake of simplicity. To be precise, if the user x blocks
user y, this will lead user y to block user x simultaneously. Similarly, unblocking operation holds the same bidirectional behavior that is two users will unblock each other at the same time.
Usage Illustration:
 Adding Text Post (commands.txt): User may create a new text post by specifying the text content, location
(longitude & latitude), and username of the friends who will be tagged to this post, each of which is separated
by TAB. Furthermore, the entity username of the post owner has been added to denote whose the post is.
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ADDPOST-TEXTselmanThis is my 1st text
 Adding Image Posts (commands.txt): Not only can a user create text post, but he/she can also create an image
or a video post. In this scenario, the image path and resolution information should be provided to the system
as well. Similar to ADDPOST-TEXT command, here the username of the post owner has been added to
parameter list.
ADDPOST-IMAGEselmanThis is my 1st image
 Add Video Post: User should only provide the file path of the video and the duration of the video. Similar to
ADDPOST-TEXT and ADDPOST-IMAGE commands, here the username of the post owner has been added to
parameter list.
ADDPOST-VIDEOselmanThis is my 1st video
You will be provided with two (tab-separated) text input files:
 Users in the system,
 Commands that you need to execute in order to test your application.
List of all users in the system will be given in the (tab-separated) users.txt file:
The format of user’s data will be given as follows:
A sample users.txt input file is given below:
Ahmet Utku ahmet ahmet12 04/25/2001 Meram Anadolu Lisesi Single
Demet Akbag demet demet00 01/16/1999 Ankara Fen Lisesi In relationship
Zeki Öztürk zeki zeki01 08/16/1987 Kadikoy Lisesi Divorced
Gizem Kocadag gizem gizem1 12/09/1997 Hacettepe Universitesi Single
Utku Anil utku utku99 10/06/1999 Bilkent Universitesi Complicated
Hakan Kocakulak hakan hakan81 03/01/1981 Orta Dogu Teknik Universitesi Single
Selman Bozkir selman selo12 11/12/1983 Hacettepe Üniversitesi Single
Hamdi Karayagiz hamdi xy253 04/02/1987 Osmangazi Üniversitesi Divorced
Aylin Yuksel aylin 45ayl2 03/12/1998 Besiktas Lisesi Single
Sevda Karaca sevda g4256 19/01/1980 Marmara Universitesi Complicated
Murat Özbayir murat murat2 06/08/1974 Ankara Universitesi Single
Necdet Emin necdet neco34 11/10/1982 Ege Üniversitesi In relationship
You are expected to create an instance for each user in this file.
List of all commands, which will be given to test your program and which you are expected to execute correctly and in
order, will be given in the (tab-separated) commands.txt file.
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ADDFRIEND ahmet demet
ADDFRIEND ahmet selman
ADDFRIEND ahmet murat
ADDFRIEND demet necdet
ADDFRIEND zeki demet
ADDFRIEND hakan murat
ADDFRIEND selman gizem
ADDFRIEND sevda murat
ADDFRIEND murat necdet
ADDFRIEND murat aylin
ADDFRIEND necdet murat
BLOCKFRIEND selman ahmet
BLOCKFRIEND gizem utku
BLOCKFRIEND utku hakan
BLOCKFRIEND gizem hamdi
BLOCKFRIEND aylin selman
BLOCKFRIEND demet necdet
ADDPOST-IMAGE selman Thanks Tram Tran for this amazing photo 12.1831 223.6153 gizem:hakan image.png 135250
ADDPOST-VIDEO selman Doctor at center of USA Gymnastics scandal 82.7331 51.7331 gizem:hakan video1.avi 67
ADDPOST-TEXT selman My nieces and nephew in my mind… 39.8833431 32.7381663 necdet
ADDPOST-TEXT demet Aurora hanging out with Pro York 39.8833431 32.7381663 hamdi:necdet
ADDPOST-TEXT demet In Oklahoma homeboy killed 3 with AR-15. 9.83431 32.7663 hamdi:necdet
ADDPOST-IMAGE demet Thanks for this amazing photo 12.183431 223.631 utku:sevda image.png 135250
Important note: DO NOT use Turkish characters in your code (anywhere, not even comments)!
In this section, usage scenarios and the points that you must pay attention are listed. Each window has been captioned
for ease of understanding. As a general rule, all JFrames must be shown at the center of the screen and their dimensions
must not be resized.
1. Login window (
This window is the startup project and the JFrame class of this window must be named with “”. The static
void main call must only be implemented in this class. Further, all initialization stages must be implemented in this
class. Thus, the JList control must be filled with usernames of the registered users. When user clicks on a user the
JList component at below the appropriate username and password must be typed in username and password
(JTextField) controls. When the system user clicks on the JButton “Login” system must check the credentials and
let the user log in or warn for the incorrect username/password combination by showing a warning message. All
messages throughout the homework must be shown by utilizing the JOptionPane.showMessageDialog function.
This window must contain three buttons (Create User, Remove User and Login). If user clicks on “Remove User”
button, then the system must ask to the system admin whether he/she is sure about operation. You can again use
JOptionPane dialogs for this confirmation. If user clicks on the “Yes” button of the Dialog then all the entries related
to deleted user must be removed from the system. Note that, this operation must also delete the removed user from
all post tags.
If system user clicks on the button of “Create User” then the Create User JFrame must be loaded and shown.
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Fig. 3 System startup JFrame.
2. Create User window (
In this JFrame, a new user can be added by providing all the required information depicted in the Fig 4. All text
fields must be checked against empty string values and password values must be doubly checked. If the required
conditions are not met your application must warn the user via JOptionPane.showMessageDialog function. If all
values are valid, then a new user must be created and added to User Collection object via a showing a “Success!”
Fig. 4 Create User JFrame.
3. Profile Page window (
This window is the core part of the assignment and it has been used to show profile pages of both logged in user
and visited friends’ profile pages. In this regard, it serves a polymorphic behavior  As can be seen in Fig. 5,
profile page form has a header, a user icon (it will be static and does not change according to the user), a panel for
presenting user information, a panel for listing both friends and blocked users and a right panel for visualizing
posts and their respective tagged users. Header part contains a hidden Home button, a textField for searching
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“available” people and the buttons of “Create Post” and “Log out”. The operation rules belonging to this window
are listed below:
 Profile page window is a polymorphic window. In other words, it should be used to show both logged
user and a friend of logged user upon user searching action. Hence, it has two view modes: (a) logged in
user view mode (See Fig. 5a and 5b), (b) visiting mode (See Fig. 6a and 6b)
 If the logged in user searches someone and double clicks on a name of one available person, profile page
must be refreshed and the all information on the profile page must be updated according to the searched
 In the logged in user view mode, the Home button must not be visible since the window is at the page of
logged in user. Therefore, the “Home” button is redundant. In visiting mode, the “Home” button must be
visible in order to allow user to come back to his/her original home page.
 If the logged in user types some characters into the “Search Friend” text field, the available users must be
listed on the search friend list just below the text field. Note that, this list is always hidden and it must
only be shown when user types some characters in the search friend text field. This JList must return to
hidden state if the user clicks anywhere else than the search list on the screen.
 The posts panel located at the right side of the JFrame is a tabbed panel (it also contains scrollable
JScrollPanes) and it comprises two post lists: (a) active user’s own posts (left tab), (b) all posts belonging
to the friends of the active user (right tab). If the profile page is in logged in user view mode, each post of
logged in user must contain a “Tag User” button for tagging the friends. In contrast, the posts in the right
tab will not contain such a button since those posts belong to other people (See Fig. 5b). On the other
hand, if the profile page is in visiting mode, all posts in both tabs will not contain any “Tag User” because
of the page mode (See Fig. 6a and 6b).
 Every post must denote its type by locating the initial character of its kind to the left of the post that is ‘T’
stands for text posts while ‘I’ denotes image posts. Similarly, video posts must be shown by the character
 Logged in user posts will be shown by presenting the post text and tagged users. On the other hand,
friends’ posts must contain a text on top of the post (e.g. “Ayse Tunc has shared”) to denote the owner of
the post. This feature is unnecessary for the logged in user posts. This discrimination is also valid for the
visiting mode.
Fig. 5a Logged in user view mode at profile page window (see the posts of the logged in user)
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Fig. 5b Logged in user view mode at profile page window (see the posts of the friends of the logged in user)
Fig. 6a Visiting mode at profile page window (see the posts of the logged in user)
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Fig. 6b Visiting mode at profile page window (see the posts of the friends of the logged in user’s friend)
 In visiting mode, “Block Friend”,”Remove Friend” and “Create Post” buttons must not be visible since
logged in user is visiting another user. Once he/she comes back at his/her own page then these buttons
must be visible again.
 In visiting mode, two additional buttons: (a) “Add Friend” (b) “Block this person” must be visible
depending on the friendship status. If the visited user is a friend of logged in user, then only the button of
“Block this person” must be visible. In contrast, if visited user is not a friend of the logged in user then
“Add Friend” must also be visible above the button of “Block this person”. Note that, for the sake of
simplicity, “Add Friend” button accepts the friendship of two people (logged user and visited user)
immediately by prompting (e.g. “You added yyy as a friend”)
 If the logged in user visits another profile and clicks on “Block this person” then system must block two
people in bi-directional way and window must return to logged in user view mode immediately
following the prompt message (e.g. “ You blocked yyy”).
 If the logged in user clicks on the button of “Create Post” then the AddPost JFrame must be shown.
 The button “Log out” makes the logged in user sign out from the system immediately (there is no need to
prompt such as “Are you sure?” for log out operation)
4. Adding Posts window (
This window is a popup window that be shown following the user click on “Create Post” button. Post type must
be picked at a Combo Box (JComboBox) from the values (a) Text Post, (b) Image Post and (c) Video Post. Different
options must be enabled depending on the post type. See Fig. 7a, 7b and 7c for details.
Note that, tagging is independent from post adding operation. A post must be first created and then tagged later
on. As mentioned before, “Tag User” button must be used to tag only your friends.
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Fig. 7a Adding of Text Post
Fig. 7b Adding of Image Post (see the additional properties and their related visual controls)
Fig. 7c Adding of Video Post (see the additional properties and their related visual controls)
In order to add a post all the relevant information should be provided. Otherwise, system must warn the user by
prompting a message box to inform user. If all the values are valid the Add Post window must be closed and the
create post must be added to the post list of the logged in user.
5. Tagging User Window (
When the logged in user clicks on the “Tag User” button of a specific post, this window must be shown. Tag User
window is a relatively simple window. However, it has a special property that is retrieving only the untagged
friends. Suppose that there exist 5 friends of the logged in user. If there is no tagged user for the Post P then all the
friends must be listed by adding their names (not user names). As it can be predicted, the Tag User window’s
responsibility is listing the untagged friends for a specific post. If a user has already been tagged for a specific post
then she/he must not be listed anymore for that post. See Fig. 8 for a Tag User window example
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Fig. 8 Tag User Window (the list must always contain all friends that can be tagged)
 Add New Friend: The system should not allow users to add a friend who is already in his/her friend or does
not exist in the system.
 Blocking a User: If the logged in user (LU) blocks another user (AU) then AU must be immediately added to
blocked user list of LU. If they were friend, this friendship must also be removed. Furthermore, LU must not be
able to see AU’s name in person search pane anymore and the tags of AU in the posts of LU must be deleted
completely. On the other hand, although AU is not directly visible to LU, LU can still see AU’s name in the post
tags lists. For the sake of simplicity, this exception is allowed.
 General constraints:
o When a user is not logged-in, he/she should be allowed only to perform a sign-in. Only after the user
signs in, other actions should be permitted.
o Users should not be able to tag other users in their posts if they are not their friends.
o It is assumed that only one user can log in to the system at a particular time, so all actions related to
users should be performed by the user who is currently logged in.
o Input files will be error free. Thus, please be ensure that your code is working and system can be
initialized without any failure.
 Submissions will be accepted only electronically via
 The deadline for submission is 19.05.2017 until 23:59.
 The submission format is:
 (your all project folder)
 uml.jpg (In this assignment I am expecting a more detailed UML class diagram including not only the
logical classes but also JFrames and their place in this ecosystem)
 Your main class must be named! All of your classes should be in the src folder (they may, however,
be further classified into other subfolders in case you decide to make packages). Note that only zipped folders
can be submitted.
 All work must be individual! Plagiarism check will be performed! Duplicate submissions will be graded with
0 and disciplinary action will be taken.
java Main users.txt commands.txt