Univenify No. 1 I I I H I H I I I I Seat No.
THE UNIVERSITY OF HONG KONG
FACULTY OF ENGINEERING
DEPARTMENT OF COMPUTER SCIENCE
-----
COMP3330 Interactive Mobile Application Design and Programming
Date: Dec 18, 2017 Time: 2:30pm-5:30pm
Only approved calculators as announced by the Examinations Secretary can be used in this
examination. It is the candidates' responsibility to ensure that their calculator operates
satisfactorily, and candidates must record the name and type of the calculator used below.
Brand name and type of calculator: - ----- - - - - --------
Special Note:
Candidates are permitted to bring to the examination ONE sheet of A4-sized paper with
printed or written notes on both sides.
Answer ALL questions (120 points).
Please write all your answers onto the answer sheets provided.
Page I of 18
Section A Multiple Choice
Ql [2 points]
Which of the following regarding smart phone operating systems is/are NOT correct?
(i) Android dominates the smart phone market for years.
(ii) Blackberry phones can only run Blackberry OS.
(iii) Python is the primitive programming language for Symbian apps development.
(iv) Windows Phone is the successor of Windows Mobile.
(v) One can install an APK file downloaded from an Internet site onto an iPhone.
(A) (i) and (iii) only
(B) (i) and (iv) only
(C) (ii) and (v) only
(D) (ii), (iii) and (v) only
(E) (ii), (iii), (iv) and (v) only
Q2 [2 points]
Which of the following Integrated Development Environments (IDEs) CAN be used to
develop Android applications?
(i) Eclipse
(ii) Xcode
(iii) Titanium
(iv) Unity
(v) MIT App Inventor
(A)(i) only
(B) (ii) only
(C) (i) and (iv) only
(D)(i), (iv) and (v) only
(E) (i), (iii), (iv) and (v) only
Page 2of18
Q3 [2 points]
Which of the following are NOT names of Android version?
(i) Fro yo
(ii) Gingerbear
(iii) Ice Cream Sandwich
(iv) Lollipop
(v) Mushroom
(A) (i) and (ii) only
(B) (ii) and (v) only
(C) (iii) and (iv) only
(D) (ii), (iii) and (v) only
(E) (i), (ii), (iii) and (v) only
Q4 [2 points]
Which of the following about the user interface design law Magic Number Seven is/are
correct?
(i) The law comes from a paper written by a cognitive psychologist George Mitcheson.
(ii) The number of objects an average human can process at any time is 7 ± 2.
(iii) A designer needs 7 ± 2 days on average to design the user interface.
(iv) The number of each kind of user interface component should be multiple of 7.
(v) The design of any user interface has to be reviewed by at least 7 other people.
(A)(i) only
(B) (ii) only
(C) (iii) only
(D)(i) and (iii) only
(E) (iv) and (v) only
Page 3of18
QS [2 points]
Which of the following is/are contained within the Android Manifest?
(i) Pennissions the application requires
(ii) List of strings used in the application
(iii) List of activities in the application
(iv) User interface layout definition
(v) Developer's infonnation
(A)(i) only
(B) (i) and (ii) only
(C) (i) and (iii) only
(D) (ii) and (iv) only
(E) (ii), (iii) and (v) only
Q6 [2 points]
Which layout has been deprecated and which layout is the latest addition to Android's
collection of layouts?
(i) AbsoluteLayout
(ii) FrameLayout
(iii) LinearLayout
(iv) RelativeLayout
(v) ConstraintLayout
(A) (i) has been deprecated and (iv) is the latest addition.
(B) (i) has been deprecated and (v) is the latest addition.
(C) (ii) has been deprecated and (iv) is the latest addition.
(D) (ii) has been deprecated and (v) is the latest addition.
(E) (iii) has been deprecated and ( v) is the latest addition
Page 4of18
Q7 [2 points]
What should be the correct order of the following statements for describing AbsoluteLayout,
FrameLayout, LinearLayout, TableLayout and RelativeLayout, respectively?
(i) Elements are organized along a single line.
(ii) You have to lay out elements based on their relationships with one another, and with
the parent container.
(iii) Multiple elements will be displayed overlapping.
(iv) You just need to define rows in the layout XML, while the columns are determined
automatically.
(v) You have to specify the exact x and y coordinates of each component.
(A) (i), (ii), (iii), (iv), (v)
(B) (i), (iii), (v), (ii), (iv)
(C) (iii), (iv), (v), (i), (ii)
(D) (v), (iii), (i), (iv), (ii)
(E) (v), (iv), (iii), (ii), (i)
Q8 [2 points]
Which of the following is a correct sequence of method execution in an Activity life cycle?
(A)onCreate () -7 onStart () -7 onResume ()
(B) onCreate () -7 onResume () -7 onStart ()
(C) onStart () -7 onCreate () -7 onResume ()
(D)onStart () -7 onResume () -7 onCreate ()
(E) onResume () -7 onStart () -7 onCreate ()
Q9 [2 points)
When activity X triggers another activity Y to be on top of X so that X is no longer visible,
which of the followings will be called for X?
(A)onStop ()
(B) onPause ()
(C) onDestroy ()
(D) onSleep ()
(E) onLeave ()
Page 5of18
QlO [2 points]
Which of the following can be included in an Intent object?
(i) Component name
(ii) Action
(iii) Category
(iv) Extra
(v) Flags
(A) (i) and (ii)
(B) (i) and (iii)
(C) (i), (ii) and (iii)
(D) (i), (iii) and (iv)
(E) (i), (ii), (iii), (iv) and (v)
Qll [2 points]
Order the following in descending order of importance.
(i) Visible process
(ii) Background process
(iii) Empty process
(iv) Service process
(v) Foreground process
(A)(i), (v), (ii), (iv), (iii)
(B) (i), (v), (iv), (ii), (iii)
(C) (iii), (v), (i), (iv), (ii)
(D) (v), (i), (iv), (ii), (iii)
(E) (v), (iv), (i), (ii), (iii)
Page 6of18
Q12 [2 points]
Which of the following is NOT an external storage public directory?
(i) DIRECTORY _DCIM
(ii) DIRECTORY DOCUMENTS
(iii) DIRECTORY MOVIES
(iv) DIRECTORY PODCASTS
(v) DIRECTORY NOTIFICATIONS
(A)(i) only
(B) (iii) only
(C) (ii) and (iii) only
(D) (iv) and (v) only
(E) None of the above
Q13 [2 points]
Which of the following are parameters of the play () method of soundPool?
(i) Left I right volume
(ii) Priority
(iii) Sound quality
(iv) Playback rate
(v) Maximum number of streams that can be played at the same time
(A) (i) and (ii) only
(B) (i), (ii) and (iv) only
(C) (ii) and (iv) only
(D) (ii), (iii) and (iv) only
(E) (i), (ii), (iii), (iv) and (v)
Page 7of18
Q14 [2 points]
Which of the following are properties that can be returned by the getLayoutParams ()
method of Rel a ti veLayout. LayoutParams?
(i) leftMargin
(ii) topMargin
(iii) height
(iv) weight
(v) gravity
(A) (i), (ii) and (iii) only
(B) (i), (ii) and (iv) only
(C) (ii), (iii) and (iv) only
(D)(ii), (iv) and (v) only
(E) (iii), (iv) and (v) only
Q15 [2 points]
Suppose SQLi teDatabase db= getWri tableDatabase ().Which of the following
operation is/are NOT valid?
(i) db. insert ( ... )
(ii) db.delete( ... )
(iii) db.update ( ... )
(iv) db. executeSQL ( ... )
(v) db. create ( ... )
(A) (i) and (ii) only
(B) (ii) and (iii) only
(C) (iv) and (v) only
(D) (i), (iii) and (iv) only
(E) (iii), (iv) and (v) only
Page 8of18
Section B Long Questions
Ql [10 points]
(a) According to statistics, game is the most popular category in the smart phone application
market. State TWO examples (2 points) and write down TWO features that applications
under this category should possess (2 points).
(b) Open Crowdsourcing and Sharing Economy are considered to be two new categories of
smart phone applications. Explain what they are ( 4 points) and state ONE example for each
of them (2 points).
Q2 [10 points]
A developer has written a simple Android application for calculating the download time (in sec)
given the download rate (in Mbits I sec) and file size (in Mbytes) as follows:
2.4 100
fif1~ $11~ (Ml"',-l:>~I
~---
CALCULATE CALCULATE
The user just needs to enter information into the two EditText fields and press the
"CALCULATE" button, the result will be displayed accordingly.
The layout file activity_ main.xml contains the following:

xmlns:tools= "http://schemas.android.com/tools"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="rnatch_parent"
tools:context="hkucs . test3.MainActivity">
android:text="Download Rate (Mbits I sec):"
android:layout_width="wrap_content "
Page 9of18
android:layout_height="wrap content" />
android:id="@+id/download_rate"
android:width="500px"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
android: text="File Size (Mbytes): 11
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
android:id="@+id/file_size"
android:width="500px"
android:layout_width="wrap content"
android:layout_height="wrap content" />
android:id="@+id/calculate_button"
android:text="CALCULATE"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
android:id="@+id/download_time"
android:text=""
android:layout_width="wrap_content"
android:layout_height="wrap_content" />

The mam program MainActivity.java is partially completed as follows. Please fill in the
missing blanks to complete the program (I point each).
package hkucs.downloadtime;
import android.support.v7.app.AppCompatActivity;
import android.as.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
Page 10of18
public class MainActivi ty extends
EditText dRate, fSize;
Button cButton;
TextView dTime;
@Override
protected void onCreate(Bundle savedinstanceState)
super.onCreate(savedinstanceState);
setContentView(R.layout. (ii) _____ );
dRate (Edi tText) (iii)
fSize (EditText) (iv)
dTime (TextView) (v)
cButton = (Button) (vi)
cButton.setOnCli ckListener(new --~~-(vii) ___ ~~
} ) ;
---~- ( viii)_~-~-
public void onClick(View v)
String dRateString
String fSizeString
double Result =
---~~-(ix)~-~~~-
_____ (x) __ ~~-
dTime . setTe xt( " Download Time= " + String.valueOf(Result)
+ " sec");
Q3 [10 points]
Please draw the following layout onto the answer sheet.

xmlns:android="http://schemas .android.com/apk/re s/android"
xmlns:app="http://schemas.android . com/apk/res- auto"
xmlns:tools="http:/ /schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_ height="matc h_paren t "
tools:layout_editor_absolut e Y="Odp"
Page 11 of18
tools:layout_editor_absoluteX="Odp">
android:id="@+id/textViewl"
android:layout_width="wrap content"
android:layout_height="wrap_content"
android:text="COMP3330"
android:textSize=''30sp''
app:layout_constraintLeft toLeftOf="parent"
app:layout constraintTop_toTopOf="parent"
android:layout_marginTop="50dp" />
android:id="@+id/textView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Examination"
android:textSize=''30sp''
app:layout_constraintRight_toRightOf="parent 11
android:layout_marginRight="60dp"
app:layout_constraintTop_toTopOf="parent"
android: layout __ marginTop="l50dp"
app:layout constraintLeft toRightOf="@id/textViewl" />
android:id="@+id/button"
android:layout_width="wrap content"
android:layout_height="wrap_content"
android:text="SUPERPASS"
android:textSize="30sp"
app: layout_ constraintHorizontal_ bias="O. 3 1'
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout constraintTop_toBottomOf="@id/textView2"
android:layout_marginTop="l50dp"/>

Page 12of18
Q4 [10 points]
(a) What are the key differences between explicit intents and implicit intents? (4 points)
(b) Consider the case of switching from MainActivityl.java to MainActivity2.java. The
following statements are included in MainActivityl .Java.
pr i vate double Al = 4.3;
private int[] Bl= {3, 3, 3, 0};
private Apple Cl= new Apple() ;
project
II where Apple is a class defined in the
Suppose that the following variables are defined in MainActivity2.java:
private double A2;
private int[] B2;
pr i vate Apple C2; II where Apple is a class defined in the project
Please write down the statements required in MainActivityl.java and MainActivity2.java
so that the values in Al, Bl and Cl in MainActivityljava can be "copied" to A2, B2 and
C2 respectively in MainActivity2.java. (4 points)
(c) Briefly explain what a broadcast receiver is. (2 points)
QS [10 points]
(a) There are two rules for Android UI control:
(i) Do not block the UI thread
(ii) Do not access the UI toolkit from outside the UI thread
Explain the rationale behind these two rules. (4 points)
(b) One solution for performing long-lasting tasks while without violating the above two rules
is to define a sub-class of AsyncTask and override the implementation of
doinBackground () and onPostExecute () methods. Explain what should be put
inside these two methods. (4 points)
(c) A student has written a timer application using Handler and the main program is as
follows, where time is a TextView component in the layout file. The application is
supposed to continuously display how much time has evolved since the application started.
Unfortunately, the application does not work. Please point out and fix the mistake. Note
that import statements are not listed for simplicity. (2 points)
public class MainActivity extends AppCompatActivity
private Long startTime;
Page 13of18
private Handler handler new Handler () ;
@Override
public void onCreate(Bundle savedinstanceState)
super.onCreate(savedinstanceState);
setContentView(R.layout.main);
startTime = System.currentTimeMillis();
handler.removeCallbacks(updateTimer);
handler.postDelayed(updateTimer, 1000);
private Runnable updateTirner
public void run() {
new Runnable() {
) ;
final TextView time= (TextView) findViewByid(R.id.tirner);
Long spentTime = System.currentTimeMillis() - startTime;
Long minius ~ (spentTime I 1000) I 60;
Long seconds ~ (spentTime I 1000) % 60;
time.setText(minius + "." +seconds);
Q6 (10 points]
(a) State a purpose of saving data into SQL database of an Android device. (I point)
(b) The main program of a certain Android application contains the following codes. Explain
how the database table is like. (2 points) Also please add a statement into onCreate ()
method for executing the SQL statement TABLE_ CREATE. (1 point)
private static final String TABLE NAME
-
~ "Spot";
private static final String COL id ~ "id" i
private static final String COL name ~ "name";
private static final String COL web ~ "web";
private static final String COL
-
phone "phone";
private static final String COL address ~ "address";
private static final String COL _image "image";
private static final String TABLE CREATE
Page 14of18
@Overr i de
"CREATE TABLE II + TABLE NAME + " ( " +
COL id + 11 INTEGER PRIMARY KEY AUTO INCREMENT , " +
COL name + " TEXT NOT NULL, 11 +
COL web + " TEXT, 11 +
COL_phone + " TEXT, " +
COL address + " TEXT , " +
COL image+" BLOB ); ";
public void onCreate(SQLiteDatabase db) {
II A missing statement for executing TABLE CREATE
(c) Assume that Spot is a class defined in the project. The class contains the variables id,
name, web, phone, address and image. The developer intents to use the method
below to retrieve the contents of the database into a list of Spot objects. Does the method
work? If yes, please explain. If not, point out and suggest how to fix any problem. (3
points)
public List getAllSpots() {
SQLiteDatabase db= getReadableDatabase();
String [ ) col umns = {
COL id, COL_ name, COL_web, COL_phone, COL_ address, COL_ image
} ;
Cursor cursor db . query(TABLE_NAME, col umns, null, null, null,
null, nu ll) ;
List spotList = new ArrayList<>();
while (cursor .moveToNext()) {
int id = cursor .getint(O);
String name= cursor . getString(O ) ;
String web = cursor.getString(O);
String phone cursor . getString( O) ;
String address = cursor.getString(O);
byte[) image= cursor.getBlob(O);
Spot spot= new Spot(id, name, web, phone, address, image);
spotList . add(spot);
cursor.close();
Page 15of18
return spotList;
(d) Complete the implementation of the insert () method below for inserting an entry into
the database table named TABLE NAME. (3 points)
public long insert(String name, String web, String phone,
String address, byte[] image) {
Q7 [10 points]
Given three types of sensors in an Android device:
(i) Accelerometer sensor
(ii) Gyroscope sensor
(iii) Proximity sensor
(a) What are their functions? (3 points)
(b) Briefly explain when their listeners should be registered and unregistered. (2 points)
(c) Write down the two handler methods that you should override when defining the listener
object. (2 points)
(d) For each of the above three types of sensors, write down what rs contained m
SensorEvent. values []. (3 points)
Q8 [10 points]
Read the following article and answer the questions thereafter.
Most Android stock trading apps in Hong Kong are rife with security risks, study shows
Increasingly investors are trading their stocks the same way as they take "selfies": with their
smartphones.
But a new study has warned some Android-based stock trading apps might be open to hackers, and
considered less safe than even mobile games apps.
A study led by Hong Kong's Mobile Security Research Lab tested and evaluated 140 selected Android
stock trade mobile apps (STMAs), including some of the most popular trading in Hong Kong, and found most
were vulnerable to malicious hacking activities, often leaving users' private information highly vulnerable.
Of the 25 evaluation criteria used in the study, 86 per cent of the apps did not pass the top five
most-critical security tests.
Page 16of18
"This report tells us that the most commonly used mobile trading apps available in Hong Kong are not
secure enough, especially STMAs," said Frankie Wong, vice chairperson oflnternal Affairs at the Professional
Information Security Association.
"Most cannot pass the evaluation test on high-severity security criteria. For example, the basic checking
of "root detection" is not done well. But it shows the security levels of STMA is much lower than for mobile
games."
Root detection refers to the ability of an app to detect so-called ''rooted" devices, or those that provide
users with privileged access to their devices
Hackers have become able to perform various malicious activities such as installing malware, modifying
the device's settings, and monitoring app activities to get confidential user information on rooted devices.
However, 86 per cent of the tested apps do not have root detection, according to the study.
The research also pointed out, most of the 140 STMAs did not implement "Two-Factor Authentication",
an important security method which increases the difficulty of password hacking.
And all the apps were rated as "insecure" during testing for malicious code injection and dynamic
debugging attacks.
"Hong Kong people cannot live without their mobile apps," said the study leader Paul Chow. "I sincerely
hope the developers, after reading this report, prioritise improving the security level of their apps."
He certainly suggested it would be safer for investors to trade stocks using mobile data, instead of Wi-Fi
and update their software as often as they can.
But the highlighted safety concerns for trading apps is an issue being felt right across other regions and
platforms too.
iOS App Store and Google Play Store removed 330 trading applications on Tuesday. The decision was
made after researcij by the Australian Securities & Investments Commission found numerous cases of fraud
involving unlicensed operators of the apps.
"We should educate the public on how to select apps that can meet high security standards," said Charles
Mok, Hong Kong Legislative Councillor (Information Technology).
"And remind developers to adopt the best practises to strengthen the security."
This article appeared in the South China Morning Post print edition as: Security loopholes found in Android stock trading apps
Published: Sunday, 06August 2017.
(a) Please write down a purpose for "rooting" an Android device. (2 points)
(b) Please write down a drawback of "rooting" an Android device. (2 points)
(c) Explain why mobile data connections (e.g. 30/40) are more secure than Wi-Fi
connections. (2 points)
(d) Two-Factor Authentication means in addition of password, one other mean is adopted in
authenticating the user. Please write down a possible mean in smart phone environment.
(2 points)
Page 17of18
(e) Suppose that you want to download a smart phone application for online banking.
Suggest a way to protect yourself from being attacked by hackers. (2 points)
Q9 [10 points]
Elderly like coming to our campus and doing exercise in the morning. Imagine that you are
an IT officer in our Computer Center and you are asked to design a navigation app for the
elderly so that they won't get loss when they are walking around the campus.
(a) Please write down any 3 steps in your development process. (3 points)
(b) If the Computer Center only has budget to develop an Android app or an iOS app but not
both, which platform will you suggest the Computer Center to develop first? Explain
your choice. (2 points)
(c) Briefly describe your design. You should write down all functions available in your app.
You can also draw how each page in your app is like. Please also write down any
external library that can possibly facilitate your development. (5 points)
END OF PAPER
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