Android studio

Tutorial: Setup for
Android Development
Adam C. Champion
CSE 5236: Mobile Application Development
Autumn 2014
Based on material from C. Horstmann [1], J. Bloch [2], C. Collins et al. [4],
M.L. Sichitiu (NCSU), V. Janjic (Imperial College London), CSE 2221 (OSU), and other sources
1

Outline
•  Getting Started
•  Android Programming
2

Getting Started (1)
•  Need to install Java Development Kit (JDK) to write
Java (and Android) programs
–  Do not install Java Runtime Environment (JRE);
JDK and JRE are different!
•  Can download the JDK for your OS at http://java.oracle.com
•  Alternatively, for OS X, Linux:
–  OS X:
•  Open /Applications/Utilities/Terminal.app

•  Type javac at command line
•  Install Java when prompt appears
–  Linux:
•  Type sudo
apt–get
install
default–jdk at command line
(Debian, Ubuntu)
•  Other distributions: consult distribution’s documentation
3

Getting Started (2)
•  After installing JDK, download Android SDK
from http://developer.android.com
•  Simplest: download and install Android Studio
bundle (including Android SDK) for your OS
•  Alternatives:
–  Download/install Android Developer Tools from this
site (based on Eclipse)
–  Install Android SDK tools by themselves, then install
ADT for Eclipse separately (from this site)
•  We’ll use Android Studio with SDK included
(easy)
5

Getting Started (3)
•  Install Android Studio directly (Windows, Mac); unzip to directory
android-‐studio, then run ./android-‐studio/bin/studio.sh (Linux)
•  You should see this:
7

Getting Started (4)
•  Strongly recommend testing
with real Android device
–  Android emulator: very slow
–  Faster emulator: Genymotion
[14], [15]
–  Install USB drivers for your
Android device!
•  Bring up the Android SDK
Manager
–  Recommended: Install
Android 2.2, 2.3.3 APIs and
4.x API
–  Do not worry about Intel x86
Atom, MIPS system images
Settings
Now you’re ready for Android development!
8

Outline
•  Getting Started
•  Android Programming
9

Introduction to Android
•  Popular mobile device
OS: 52% of U.S.
smartphone market [8]
•  Developed by Open
Handset Alliance, led by
Google
•  Google claims 900,000
Android device
activations [9]
Source: [8]
10

Android Highlights (1)
•  Android apps execute on
Dalvik VM, a “clean-room”
implementation of JVM
–  Dalvik optimized for efficient
execution
–  Dalvik: register-based VM,
unlike Oracle’s stack-based
JVM
–  Java .class bytecode translated
to Dalvik EXecutable (DEX)
bytecode, which Dalvik
interprets
12

Android Highlights (2)
•  Android apps written in Java 5
–  Actually, a Java dialect (Apache Harmony)
–  Everything we’ve learned still holds
•  Apps use four main components:
–  Activity: A “single screen” that’s visible to user
–  Service: Long-running background “part” of app (not
separate process or thread)
–  ContentProvider: Manages app data (usually stored in
database) and data access for queries
–  BroadcastReceiver: Component that listens for particular
Android system “events”, e.g., “found wireless device”,
and responds accordingly
13

App Manifest
•  Every Android app must include an
AndroidManifest.xml file describing functionality
•  The manifest specifies:
–  App’s Activities, Services, etc.
–  Permissions requested by app
–  Minimum API required
–  Hardware features required, e.g., camera with
autofocus
–  External libraries to which app is linked, e.g., Google
Maps library
14

Activity Lifecycle
•  Activity: key building
block of Android apps
•  Extend Activity class,
override onCreate(),
onPause(), onResume()
methods
•  Dalvik VM can stop any
Activity without warning,
so saving state is important!
•  Activities need to be
“responsive”, otherwise
Android shows user “App
Not Responsive” warning:
–  Place lengthy operations in
Runnable Threads,
AsyncTasks
Source: [12]
15

App Creation Checklist
•  If you own an Android device:
–  Ensure drivers are installed
–  Enable developer options on device under Settings,
specifically USB Debugging
•  Android 4.2+: Go to Settings→About phone, press Build number 7
times to enable developer options
•  For Android Studio:
–  Under File→Settings→Appearance, enable “Show tool
window bars”; the Android view shows LogCat, devices
–  Programs should log states via android.util.Log’s
Log.d(APP_TAG_STR,
“debug”), where APP_TAG_STR is a
final String tag denoting your app

–  Other commands: Log.e() (error); Log.i() (info); Log.w()
(warning); Log.v() (verbose) – same parameters 16

Creating Android App (1)
•  Creating Android app
project in Android
Studio:
–  Go to File→New Project
–  Enter app, project name
–  Choose package name
using “reverse URL”
notation, e.g.,
edu.osu.myapp

–  Select APIs for app, then
click Next
17

Creating Android App (2)
•  Determine what kind of
Activity to create; then
click Next
–  We’ll choose a Blank
Activity for simplicity
•  Enter information about
your Activity, then click
Finish
•  This creates a “Hello
World” app
18

Deploying the App
•  Two choices for deployment:
–  Real Android device
–  Android virtual device
•  Plug in your real device;
otherwise, create an Android
virtual device
•  Emulator is slow. Try Intel
accelerated version, or perhaps
http://www.genymotion.com/

•  Run the app: press “Run”
button in toolbar
19

Underlying Source Code
package
edu.osu.helloandroid;

import
android.os.Bundle;

import
android.app.Activity;

import
android.view.Menu;

public
class
MainActivity
extends
Activity

{

@Override

protected
void
onCreate(Bundle
savedInstanceState)

{

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

}

@Override

public
boolean
onCreateOptionsMenu(Menu
menu)

{

//
Inflate
the
menu;
this
adds
items
to
the
action
bar
if
it
is
present.

getMenuInflater().inflate(R.menu.main,
menu);

return
true;

}

}

src/…/MainActivity.java

20

Underlying GUI Code
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"

xmlns:tools="http://schemas.android.com/tools"

android:layout_width="match_parent"

android:layout_height="match_parent"

android:paddingBottom="@dimen/activity_vertical_margin"

android:paddingLeft="@dimen/activity_horizontal_margin"

android:paddingRight="@dimen/activity_horizontal_margin"

android:paddingTop="@dimen/activity_vertical_margin"

tools:context=".MainActivity"
>

<TextView

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:text="@string/hello_world"
/>

</RelativeLayout>

res/layout/activity_main.xml

– RelativeLayouts are quite complicated. See [13] for details 21

The App Manifest
<?xml
version="1.0"
encoding="utf-‐8"?>

<manifest
xmlns:android="http://schemas.android.com/apk/res/android"

package="edu.osu.helloandroid"

android:versionCode="1"

android:versionName="1.0"
>

<uses-‐sdk

android:minSdkVersion="8"

android:targetSdkVersion="17"
/>

<application

android:allowBackup="true"

android:icon="@drawable/ic_launcher"

android:label="@string/app_name"

android:theme="@style/AppTheme"
>

<activity

android:name="edu.osu.helloandroid.MainActivity"

android:label="@string/app_name"
>

<intent-‐filter>

<action
android:name="android.intent.action.MAIN"
/>

<category
android:name="android.intent.category.LAUNCHER"
/>

</intent-‐filter>

</activity>

</application>

</manifest>

AndroidManifest.xml

22

A More Interesting App
•  We’ll now examine an
app with more features:
WiFi Tester (code on
class website)
•  Press a button, scan for
WiFi access points
(APs), display them
23

Underlying Source Code (1)

@Override

public
void
onCreate(Bundle
savedInstanceState)

{

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_wi_fi);

//
Set
up
WifiManager.

mWifiManager
=
(WifiManager)
getSystemService(Context.WIFI_SERVICE);

//
Create
listener
object
for
Button.
When
Button
is
pressed,
scan
for

//
APs
nearby.

Button
button
=
(Button)
findViewById(R.id.button);

button.setOnClickListener(new
View.OnClickListener()

{

public
void
onClick(View
v)

{

boolean
scanStarted
=
mWifiManager.startScan();

//
If
the
scan
failed,
log
it.

if
(!scanStarted)
Log.e(TAG,
"WiFi
scan
failed...");

}

});

//
Set
up
IntentFilter
for
"WiFi
scan
results
available"
Intent.

mIntentFilter
=
new
IntentFilter();

mIntentFilter.addAction(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION);

}
24

Underlying Source Code (2)
•  Code much more complex
•  First get system WifiManager

•  Create listener Object for button that
performs scans
•  We register Broadcast Receiver,
mReceiver, to listen for
WifiManager’s “finished scan” system
event (expressed as Intent
WifiManager.SCAN_RESULTS_

AVAILABLE_ACTION)
•  Unregister Broadcast Receiver when
leaving Activity

@Override

protected
void
onResume()

{

super.onResume();

registerReceiver(mReceiver,

mIntentFilter);

}

@Override

protected
void
onPause()

{

super.onPause();

unregisterReceiver(mReceiver);

}

25

The Broadcast Receiver
private
final
BroadcastReceiver
mReceiver
=
new
BroadcastReceiver()

{

@Override

public
void
onReceive(Context
context,
Intent
intent)

{

String
action
=
intent.getAction();

if
(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION.equals(action))

{

Log.e(TAG,
"Scan
results
available");

List<ScanResult>
scanResults
=
mWifiManager.getScanResults();

mApStr
=
"";

for
(ScanResult
result
:
scanResults)

{

mApStr
=
mApStr
+
result.SSID
+
";
";

mApStr
=
mApStr
+
result.BSSID
+
";
";

mApStr
=
mApStr
+
result.capabilities
+
";
";

mApStr
=
mApStr
+
result.frequency
+
"
MHz;";

mApStr
=
mApStr
+
result.level
+
"
dBmnn";

}

//
Update
UI
to
show
all
this
information.

setTextView(mApStr);

}

}

};

26

User Interface
Updating UI in code
private
void
setTextView(String
str)

{

TextView
tv
=
(TextView)

findViewById(R.id.textview);

tv.setMovementMethod(new

ScrollingMovementMethod());

tv.setText(str);

}

•  This code simply has the UI display
all collected WiFi APs, makes the
text information scrollable
UI Layout (XML)
<LinearLayout
xmlns:android="http://schemas.android.com/apk/
res/android"

xmlns:tools="http://schemas.android.com/tools"

android:layout_width="fill_parent"

android:layout_height="fill_parent"

android:orientation="vertical">

<Button



android:id="@+id/button"

android:text="@string/button_text"/>

<TextView

android:id="@+id/header"



android:text="@string/ap_list"

tools:context=".WiFiActivity"

android:textStyle="bold"

android:gravity="center">

</TextView>

<TextView


android:layout_height="fill_parent"

tools:context=".WiFiActivity"

android:id="@+id/textview"

android:scrollbars="vertical">

</TextView>

</LinearLayout>

27

Android Programming Notes
•  Android apps have multiple points of entry: no main() method
–  Cannot “sleep” in Android
–  During each entrance, certain Objects may be null

–  Defensive programming is very useful to avoid crashes, e.g.,
if
(!(myObj
==
null))
{
//
do
something
}

•  Java concurrency techniques are required
–  Don’t block the “main” thread in Activities
–  Implement long-running tasks such as network connections
asynchronously, e.g., as AsyncTasks
–  Recommendation: read [4]; chapter 20 [10]; [11]
•  Logging state via android.util.Log throughout app is essential
when debugging (finding root causes)
•  Better to have “too many” permissions than too few
–  Otherwise, app crashes due to security exceptions!
–  Remove “unnecessary” permissions before releasing app to public
•  Event handling in Android GUIs entails many listener Objects
28

Concurrency: Threads (1)
•  Thread: program unit (within process) executing independently
•  Basic idea: create class that implements Runnable interface
–  Runnable has one method, run(), that contains code to be executed
–  Example:
public
class
OurRunnable
implements
Runnable

{

public
void
run()

{

//
run
code

}

}

•  Create a Thread object from Runnable and start() Thread, e.g.,
Runnable
r
=
new
OurRunnable();

Thread
t
=
new
Thread(r);

t.start();

•  Problem: this is cumbersome unless Thread code is reused
29

Concurrency: Threads (2)
•  Easier approach: anonymous inner classes, e.g.,
Thread
t
=
new
Thread(new
Runnable(

{

public
void
run()

{

//
code
to
run

}

});

t.start();

•  Idiom essential for one-time network connections in
Activities
•  However, Threads can be difficult to synchronize,
especially with UI thread in Activity. AsyncTasks are
better suited for this
30

Concurrency: AsyncTasks
•  AsyncTask encapsulates asynchronous task that interacts with UI thread
in Activity:
public
class
AsyncTask<Params,
Progress,
Result>

{

protected
Result
doInBackground(ParamType
param)

{

//
code
to
run
in
background

publishProgress(ProgressType
progress);
//
UI

…

return
Result;

}

protected
void
onProgressUpdate(ProgressType
progress)

{

//
invoke
method
in
Activity
to
update
UI

}

}

•  Extend AsyncTask with your own class
•  Documentation at http://developer.android.com
31

References (1)
1.  C. Horstmann, Big Java Late Objects, Wiley, 2012. Online: http://proquest.safaribooksonline.
com.proxy.lib.ohio–state.edu/book/–/9781118087886
2.  J. Bloch, Effective Java, 2nd ed., Addison–Wesley, 2008. Online: http://proquest.
safaribooksonline.com.proxy.lib.ohio–state.edu/book/programming/java/9780137150021
3.  S.B. Zakhour, S. Kannan, and R. Gallardo, The Java® Tutorial: A Short Course on the Basics,
5th ed., Addison–Wesley, 2013. Online: http://proquest.safaribooksonline.com.proxy.lib.
ohio–state.edu/book/programming/java/9780132761987
4.  C. Collins, M. Galpin, and M. Kaeppler, Android in Practice, Manning, 2011. Online:
http://proquest.safaribooksonline.com.proxy.lib.ohio–state.edu/book/programming/android/
9781935182924
5.  M.L. Sichitiu, 2011, http://www.ece.ncsu.edu/wireless/MadeInWALAN/AndroidTutorial/PPTs/
javaReview.ppt
6.  Oracle, http://docs.oracle.com/javase/1.5.0/docs/api/index.html
7.  Wikipedia, https://en.wikipedia.org/wiki/Vehicle_Identification_Number
8.  Nielsen Co., “Smartphone Milestone: Half of Mobile Subscribers Ages 55+ Own
Smartphones”, 22 Apr. 2014, http://www.nielsen.com/us/en/insights/news/2014/
smartphone-milestone-half-of-americans-ages-55-own-smartphones.html
9.  Android Open Source Project, http://www.android.com
33

References (2)
10.  http://bcs.wiley.com/he-bcs/Books?action=index&itemId=1118087887&bcsId=7006
11.  B. Goetz, T. Peierls, J. Bloch, J. Bowbeer, D. Holmes, and D. Lea, Java Concurrency in
Practice, Addison-Wesley, 2006, online at
http://proquest.safaribooksonline.com/book/programming/java/0321349601
12.  https://developer.android.com/guide/components/activities.html
13.  https://developer.android.com/guide/topics/ui/declaring-layout.html#CommonLayouts
14.  https://cloud.genymotion.com/page/doc/#collapse4
15.  http://blog.zeezonline.com/2013/11/install-google-play-on-genymotion-2-0/
34

Android studio

More Related Content

What's hot (18)

Viewers also liked (6)

Similar to Android studio (20)

Recently uploaded (20)

Android studio