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Lab7 Building a Bank App using Android Studio

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EECS1022 (M,N,O)
Lab7 (Mobile Computing Part 1)
Building a Bank App using Android Studio

• The format of this lab (to be completed in Android Studio) is different from those of all
previous labs (completed in Eclipse). Read the instructions carefully.

• To complete this lab, it is strictly forbidden for you to use any library class (e.g., ArrayList,
Arrays). Violating this requirement will cause a 50% penalty on your lab marks.
• For this lab, you will be graded not only by JUnit tests given to you, but also additional
tests covering some other input values. This is to encourage you to take more responsibility
for the correctness of your code, by writing your own tests.
• Your lab assignment is not graded during the weekly scheduled lab sessions.
– Follow the instructions to submit (via eClass) the required file(s) for grading.
– Emailing your solutions to the instructor or TAs will not be acceptable.
• Texts in blue are hyperlinks to the corresponding documents/recordings.

Contents
1 Task 1: Complete Weekly Java Tutorial Videos 4
2 Task 2: Setup an Android Studio Project 5
2.1 Step 1: Install Android Studio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2 Step 2: Set up an Empty Activity in Android Studio . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.3 Step 3: Download and Replace the Controller Class and JUnit Test Class . . . . . . . . . . . . . . . 6
3 Task 3: Develop a Mobile App in Android Studio 7
3.1 Step 1: Study the Bank Problem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.2 Step 2: Using JUnit Tests to Develop Classes in Model Package . . . . . . . . . . . . . . . . . . . . . 7
3.2.1 Inferring Model Classes from JUnit Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.2.2 Status of Bank . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.2.3 Hints and Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.3 Step 3: Design a GUI Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.3.1 Given GUI Layout to Implement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.3.2 Assumed Usage Pattern of the App . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.4 Step 4: Develop the Controller Class . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4 Submission 11
Learning Outcomes
By completing the assigned exercises of this lab, you are expected to be able to:
1. Apply the Model-View-Controller (MVC) Pattern.
2. Design and Implement a GUI for a Bank App.
3. Practice Event-Driven Programming:
• Spinner (Drop-Down Menu List)
• Text View
• Edit Text Field
• Button
4. Practice the pattern of controller: multiple buttons that access and modify a single, shared object (i.e., Bank
object).
5. Attach Controller Methods to GUI Components
6. Implement model classes:
• multiple model classes: attributes in a model class are of array-referenced types.
• local variable declarations
• variable assignments
• object creations
• method calls using the dot notation
2
Assumptions
• You have already setup a Github account and stored work in a private repository: EECS1022-W21-workspace.
Note. You only submit your lab through eClass, not Github. Though not required, it is highly recommended
that you adapt to the practice of backing your work using a versioning tool like Github.
• You are able to use Android Studio to complete the tutorial videos and this lab assignment on either your
own machine or the EECS remote labs.
Requirements of this Lab
• For this lab, you will be graded not only by JUnit tests given to you, but also additional tests covering
some other input values. This is to encourage you to take more responsibility for the correctness of your code,
by writing your own tests.
• Programming Requirements
– You are only allowed to use primitive arrays (e.g., int[], String[], Facility[]) for declaring attributes and implementing methods.
– Any use of a Java library class or method is forbidden (that is, use selections and loops to build your
solution from scratch instead):
∗ Here are some examples of forbidden classes/methods: Arrays class (e.g., Arrays.copyOf), System
class (e.g., System.arrayCopy), ArrayList class, String class (e.g., substring).
∗ The use of some library classes does not require an import statement, but these classes are also
forbidden to be used.
∗ Here are the exceptions (library methods which you are allowed to use if needed):
· String class (equals, format)
Violating this requirement will cause a 50% penalty on your lab marks.
• Your lab submission will only be graded using JUnit (for this lab, the tests supplied to you plus some
additional tests).
• For the JUnit test class Tests.java given to you:
– Do not modify the test methods given to you.
– You are allowed to add new nest methods.
• For each method which you are required to implement, derived from the JUnit test methods:
– No System.out.println statements should appear in it.
– No Scanner operations (e.g., input.nextInt()) should appear in it.
Instead, declare input parameters of the method as indicated by the JUnit tests.
• You are welcome to ask questions related to this lab or the assigned tutorial videos on the forum. However,
please be cautious:
– You can help your fellow students understand the requirements of tasks.
– Do not share the code you developed to ask, or to answer, questions.
∗ Questions specific to the code you write would be best and most effectively addressed by TAs (during
scheduled labs) or your instructor (during office hours or appointments).
∗ Week 9’s tutorial videos shows to you debugger in Android Studio (which should be used in
the same manner as Eclipse debugger). You are encouraged to set breakpoints and launch the
debugger when you are stuck at your own program.
– Hints on how the solution should look like are left only to the instructors who moderate the forum.
3
1 Task 1: Complete Weekly Java Tutorial Videos
• For Lab7, you are assigned to study Week 9 Part A1 to Part B4 of the Java tutorial series:
https://www.youtube.com/playlist?list=PL5dxAmCmjv_64z4oGXy0kHBO7_gPkjNmG [ Week 9 only ]
To reference tutorial videos from the previous weeks, see:
https://www.youtube.com/playlist?list=PL5dxAmCmjv_6wy2m0yq2wObIWPz4tAxW6 [ All Weeks ]
These Java tutorial videos assigned to you are meant for you to:
1. Obtain extra hands-on programming experience on Java, supplementing your weekly lectures.
2. Complete the lab assignment with the necessary skills and background.
Though we do not require the submission of the weekly Java tutorial project (like in Lab0), examples and
insights discussed in these tutorials will be covered in your (written and programming) tests
and exam: should you decide to skip the weekly tutorial videos, it would be your choice.
As you study through the example Java classes in the tutorial videos, you are advised to type them out
(but absolutely feel free to add new Java classes to experiment) on Android Studio.
• You can find the iPad notes of illustrations from the tutorial videos here:
https://www.eecs.yorku.ca/˜jackie/teaching/tutorials/notes/EECS1022%20Tutorial%20on%20Java.pdf
Notes from Lab6 and Lab7
• See this notes on how to manipulate objects with reference-typed, multi-valued attributes:
https://www.eecs.yorku.ca/˜jackie/teaching/lectures/2021/W/EECS1022/notes/EECS1022_W21_Tracing_
PointCollectorTester.pdf
• See this notes on how to infer classes and methods from given JUnit tests:
https://www.eecs.yorku.ca/˜jackie/teaching/lectures/2021/W/EECS1022/notes/EECS1022_W21_Inferring_
Classes_from_JUnit.pdf
• You can find here the example covered in the notes for practice:
– Starter: https://www.eecs.yorku.ca/˜jackie/teaching/lectures/2021/W/EECS1022/notes/EECS1022_
W21_Inferring_Classes_from_JUnit.zip
– Solution: https://www.eecs.yorku.ca/˜jackie/teaching/lectures/2021/W/EECS1022/notes/EECS1022_
W21_Inferring_Classes_from_JUnit_Solution.zip
4
2 Task 2: Setup an Android Studio Project
Starting Task 2 should mean that you have already completed the weekly Java tutorial videos (Section 1).
2.1 Step 1: Install Android Studio
See the detailed PDF instructions “Install Android Studio 3.6.3 File” on the M,N,O eClass site: https://
eclass.yorku.ca/eclass/pluginfile.php/2004743/mod_resource/content/2/Installing_Android_Studio_
v3.6.3.pdf.
2.2 Step 2: Set up an Empty Activity in Android Studio
Unlike previous labs, there is no project archive file for you to import. Instead, you are asked to create an
Empty Activity in Android Studio:
1. Launch Android Studio and click on Create New Project.
2. Under Select a Project Template, select Empty Activity.
3. Under Configure Your Project:
• Name: type Bank
• Package Name: type eecs1022.lab7.bank
• Save Location: make sure the last part of the path should match the app name Bank
• Language: choose Java
5
4. After the new project is successfully built:
4.1 Under app/java/eecs1022.lab7.bank, create a new package called model.
4.2 Under app/java/eecs1022.lab7.bank (test), rename the JUnit test class ExampleUnitTest to Tests.
4.3 After performing the above steps, your project structure in Android Studio should look like:
2.3 Step 3: Download and Replace the Controller Class and JUnit Test Class
1. From eClass, download the archive file EECS1022 W21 Lab7.zip, containing:
• The controller class: MainActivity.java
• The JUnit test class: Tests.java
2. As shown in the left figure, do the following replacements:
• Copy and replace the given MainActivity.java to your project folder:
Bank/app/src/main/java/eecs1022/lab7/bank
• Copy and replace the given Tests.java to your project folder:
Bank/app/src/test/java/eecs1022/lab7/bank
It is expected that compilation errors exist in both given files when first
replaced into your project. See Section 3.2.1.
6
3 Task 3: Develop a Mobile App in Android Studio
3.1 Step 1: Study the Bank Problem
You are required to develop an object-oriented program solving the problem of a (simplified) bank, which provides
services (i.e., deposit, withdraw, transfer, and print statement) to a collection of up to 6 clients (i.e., when a 7th
client is attempted to be added to the bank, there should be an error message displayed). Each client can be
characterized by their name, numerical balance (always displayed with two digits after the decimal point), and a
history (i.e., collection) of up to 10 transactions (for this you can assume that the user will not complete more than
10 transactions for each client). Each client should be identified by their name. We may want to perform one of
the following kinds of transactions:
• Deposit some input amount of money to a client’s account (identified by their name).
• Withdraw some input amount of money from a client’s account (identified by their name).
• Transfer some input amount of money from a client’s account to another client’s account (identified by their
names). In the case of transferring $amount from client c1 to client c2, it should be considered as two separate
transactions: a withdrawal of $amount from client c1 and a deposit of $amount to client c2.
Also, throughout the life time of a bank object, given a client’s name, we may want to it return a statement
summarizing the client’s status (i.e., account balance) and their history list of transactions.
3.2 Step 2: Using JUnit Tests to Develop Classes in Model Package
3.2.1 Inferring Model Classes from JUnit Tests
• It is expected that the Tests JUnit class (which you downloaded and copied from eClass) contains compilation errors. This is because that declarations and definitions of the required class(es) and method(s) it
references are missing.
• The model package you created is empty. Class(es) and method(s) derived from the given JUnit class must
be added to this package. You must not create any classes not indicated by the JUnit tests, otherwise your
submitted model classes will not compile with the grading program.
Therefore, your tasks are:
1. Inferring from the given JUnit tests, add the missing class(es) and method(s) into the model package.
Note a line from the Tests class (which specifies that all classes from the model package are referenced):
import eecs1022.lab7.bank.model.*;
2. Pass all JUnit tests given to you (i.e., a green bar).
You must not modify these given JUnit tests, as they suggest how the intended class(es) and
method(s) should be declared.
How to Deal with a Failed JUnit Test? Like the previous labs, in Android Studio, place breakpoints around
assertions of the failed tests, launch the debugger, and then use the “step over”, “step into”, “step out”, Variables,
and Watches tools to help fix your code. See Java Tutorials Week 9 for how to use all these.
7
3.2.2 Status of Bank
A bank’s status reports whether or not the last invoked service (i.e., add a new account, deposit, withdraw, transfer,
or print statement) results in an error:
• When there is an error upon invoking the service, the bank’s status should be the corresponding error message.
• Otherwise, when there is no error upon invoking the service, the bank’s status should be a summary of each
stored account’s status (see the given JUnit tests).
When multiple errors occur simultaneously, exactly one message for the lowest-ranked error is
displayed. For example, say the number of clients has not reached the maximum yet, then given a clashing name
(an error with rank 2) and a non-positive initial balance (an error with rank 3), we only output the error message
Error: Client n already exists.
Add a New Account
Inputs: Name of client (say n) and the Initial Balance of client (say bal)
Rank Error Condition Error Message
1 Number of accounts in bank has reached its maximum Error: Maximum Number of Accounts Reached
2 n clashes with the name of some existing client Error: Client n already exists
3 bal is non-positive (i.e., ≤ 0) Error: Non-Positive Initial Balance
Confirm: Case of a DEPOSIT Transaction
Inputs: DEPOSIT chosen as the service type, name of to-account (say toName), and amount of transaction (say
amount).
Rank Error Condition Error Message
1 toName is not an existing client’s name Error: To-Account toName does not exist
2 amount is non-positive (i.e., ≤ 0) Error: Non-Positive Amount
Confirm: Case of a WITHDRAW Transaction
Inputs: WITHDRAW chosen as the service type, name of from-account (say fromName), and amount of transaction
(say amount).
Rank Error Condition Error Message
1 fromName is not an existing client’s name Error: From-Account fromName does not exist
2 amount is non-positive (i.e., ≤ 0) Error: Non-Positive Amount
3 amount is larger than from-account’s balance Error: Amount too large to withdraw
Confirm: Case of a TRANSFER Transaction
Inputs: TRANSFER chosen as the service type, name of from-account (say fromName), name of to-account (say
toName), and amount of transaction (say amount).
Rank Error Condition Error Message
1 fromName is not an existing client’s name Error: From-Account fromName does not exist
2 toName is not an existing client’s name Error: To-Account toName does not exist
3 amount is non-positive (i.e., ≤ 0) Error: Non-Positive Amount
4 amount is larger than from-account’s balance Error: Amount too large to transfer
Confirm: Case of a Print Statement Service
Inputs: Name of a client (say n)
Error Condition Error Message
n is not an existing client’s name Error: From-Account n does not exist
8
3.2.3 Hints and Requirements
• See this notes on how to declare and manipulate reference-typed, multi-valued attributes:
https://www.eecs.yorku.ca/˜jackie/teaching/lectures/2021/W/EECS1022/notes/EECS1022_W21_Tracing_
PointCollectorTester.pdf
• See this notes on how to infer classes and methods from given JUnit tests:
https://www.eecs.yorku.ca/˜jackie/teaching/lectures/2021/W/EECS1022/notes/EECS1022_Inferring_
Classes_and_Methods_from_JUnit_Tests.pdf
Programming IDEs such as Eclipse and Android Studio are able to fix such compilation errors for you.
However, you are advised to follow the guidance as specified in the notes to fix these compilation
errors manually, because: 1) it helps you better understand how the intended classes and
methods work together; and 2) you may be tested in a written test or exam without the
assistance of IDEs.
• Any new class(es) you add must reside in the model package.
– Once the necessary class(es) and method(s) are declared, you can add as many attributes as necessary
to implement the body of each method.
– Study carefully example instances as specified in Tests.java: they suggest the how the intended class(es)
and method(s) should be declared and implemented.
– Focus on gradually passing one test at a time.
3.3 Step 3: Design a GUI Layout
3.3.1 Given GUI Layout to Implement
You are then asked to implement the following GUI design:
In the left GUI design:
• Textviews (for displaying input prompts) are boxed in green.
• Plain Texts (or textfields for reading user-typed inputs) are
boxed in blue.
• The spinner (for displaying a drop-down menu of options) is
boxed in orange.
• Buttons (for invoking attached controller methods) are boxed
in red.
• The (invisible) textview (for displaying computation results) is
boxed in purple.
To implement the above GUI design, open activity main.xml
(under app/src/main/res/layout) in Android Studio.
Then, drag, drop, and organize the above specified GUI components.
For each GUI component, be sure to set the appropriate text, as
suggested above, and set its id to be used later in the controller
(MainActivity.java).
9
3.3.2 Assumed Usage Pattern of the App
For the simplicity of this lab, you can assume that users (or testers) of your app behave in the following way:
1. Adding a New Account
1.1 Enter the name of a new client.
1.2 Enter the initial balance of this new client.
1.3 Click on the button “ADD A NEW ACCOUNT”
This step should cause your program to create a Client object, and add it to the Bank object’s array
attribute clients.
See Section 3.2.2 for the possible error messages to be displayed.
2. Completing a New Transaction
2.1 Select a service type (i.e., DEPOSIT, WITHDRAW, TRANSFER).
2.2 Enter the To and/or From account owners:
• In the case of deposit, input on the To-Account textfield should be retrieved; any input on the
From-Account textfield should be ignored.
• In the case of withdraw, input on the From-Account textfield should be retrieved; any input on the
To-Account textfield should be ignored.
2.3 Enter the amount for the selected service type.
2.4 Click on the “CONFIRM” button.
In cases of DEPOSIT and WITHDRAW, this step should cause your program to add a new transaction to,
respectively, the to-account and the from-account. In the case of TRANSFER, a “withdraw” transaction
should be added to the from-account, and a “deposit” transaction should be added to the to-account.
See Section 3.2.2 for the possible error messages to be displayed.
3. Printing the Statement
3.1 Select the service type (i.e., Print Statement).
3.2 Input on the From-Account textfield should be retrieved; any input on the To-Account textfield should
be ignored.
3.3 Click on the “CONFIRM” button.
See Section 3.2.2 for the possible error messages to be displayed.
The two buttons “ADD A NEW ACCOUNT” and “CONFIRM” may be clicked in any order.
3.4 Step 4: Develop the Controller Class
From Section 2.3, you already copied and replaced the given controller class MainActivity.
• Follow through the comments/hints in the given controller file to complete it.
• Refer to this short demo tutorial video on how your Android mobile app is supposed to work: https:
//www.youtube.com/watch?v=xal9NkIs46U&list=PL5dxAmCmjv_7YgI2LgcwjWTHiNZSR-aQX&index=2
• Test the app by launching it using an emulator in Android Studio:
• The app name on the top of the emulator screen must read:
Bank App – FirstName LastName (StudentNumber)
where your first name, last name, and student number are displayed in the suggested order.
Hint: Go to the resource file app/res/values/strings.xml and modify the app name attribute accordingly.
10
4 Submission
1. Before you submit, you must make sure that there are no compilation errors in the given JUnit test class
and in all classes you have created in the model package.
Submitting programs with errors (meaning that it cannot be run for grading) will result in
possible partial, but low, marks.
2. Go to the eClass site for Sections M,N,O: https://eclass.yorku.ca/eclass/course/view.php?id=6214
3. Under the Lab Submissions section, click on Lab7 to submit the following list of files:
• All Java files in the model package (as indicated by the given Tests.java):
Bank/app/src/main/java/eecs1022/lab7/bank/model
• The completed controller file: Bank/app/src/main/java/eecs1022/lab7/bank/MainActivity.java
• The completed GUI layout file: Bank/app/src/main/res/layout/activity main.xml
• The strings resource file: Bank/app/src/main/res/values/strings.xml
Note:
• You may upload as many draft versions as you like before the deadline.
• You must explicitly submit the draft version for grading before the deadline.
• Once you click on the submit button, you can no longer upload another draft version.
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