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Android
by
Somenath Mukhopadhyay
+91 9748185282
som@som-itsolutions.com
som.mukhopadhyay@gmail.com
What is ANDROID
•
➔
•
- Google's Android is an open-source platform that's
currently available on a wide variety of smart phones.
- Android is a software stack for mobile devices that
includes an operating system, middleware and key
applications.
Advantages of Android
- Full phone software stack including
applications

- Designed as a platform for software
development

- Android is open

- Android is free

- Community support

- 100% Java Phone
➔
History of Android
July 2005
Google acquired Android Inc.
Nov 2007
Open HandSet Alliance formedGoogle, HTC, Intel, Motorola, Qualcomm,T-Mobile
Android is the OHA first product
Nov 2007
OHA released a preview of the Android OHA
ANDROID ARCHITECTURE
The software stack is split into Four Layers:
•
•
•
•
-
The
The
The
The
application layer
application framework
libraries and runtime
kernel
LINUX KERNEL
The architecture is based on the Linux2.6 kernel. Android use Linux kernel as its hardware abstraction layer between the hardware and rest of the software.
It also provides memory management, process management, a security model, and networking, a lot of core operating system infrastructures that are robust and have been proven over time
NATIVE LIBRARIES
•The next level up is the native libraries. Everything that you see here in green is written in C and C++.
Android Run Time
The Android Runtime was designed specifically for Android to meet the needs of running in an embedded environment where you have limited battery, limited memory, limited CPU.
The DVM runs something called dex files, D­E­X and these are byte codes that are the results of converting at build time. Class and JAR Files.
Android Run Time
•This is in blue, meaning that it's written in the Java programming language.
•The core library contains all of the collection classes, utilities, IO, all the utilities and tools that you’ve come to expected to use.
Application Framework
This is all written in a Java programming language and the application framework is the toolkit that all applications use.
•These applications include the ones that come with a phone like the home applications, or the phone application. •It includes applications written by Google, and it includes apps that will be written by you. •So, all apps use the same framework and the same APIs.
APPLICATION LAYER
•
And the final layer on top is Applications. •This is where all the applications get written. •It includes the home application, the contacts application, the browser, and your apps. •And everything at this layer is, again, using the same app framework provided by the layers below.
Android Building Blocks
These are the most important parts of the Android APIs:
AndroidManifest.xml
-the control file-tells the system what to do with the top-level components
Activities
-an object that has a life cycle-is a chunk of code that does some work
Views
-an object that knows how to draw itself to the screen
Intents
-a simple message object that represents an "intention" to do something
Notifications
-is a small icon that appears in the status bar(SMS messages)
-for alerting the user
Services
-is a body of code that runs in the background

Android App Development
●
Android SDK
●
Android Studio
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Eclipse with ADT plugin
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Development in emulator
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Development in Real Device A HelloWorld Application in Android
Studio
AndroidManifest.xml
➔
Build.gradle
➔
MainActivity.java
➔
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.som_itsolutions.myapplication" >
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name=".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>
build.gradle
apply plugin: 'com.android.application'
android {
compileSdkVersion 22
buildToolsVersion "22.0.1"
defaultConfig {
applicationId "com.som_itsolutions.myapplication"
minSdkVersion 16
targetSdkVersion 22
versionCode 1
versionName "1.0"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguardrules.pro'
}
}
}
dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
compile 'com.android.support:appcompat-v7:22.2.1'
}
Android Build Process Overview
Gradle build system
build.gradle – standard name for build file
➔
Comprises of tasks
➔
task compileTask << {
➔
System.out.println "compiling..."
}
➔
Type gradle -q tasks
Result will be
➔
Other tasks
----------compileTask
Gradle Build system
To run the previous compileTask type
gradle -q compileTask
A simple build.gradle file
defaultTasks 'buildTask'
task compileTask << {
System.out.println "compiling..."
}
task buildTask (dependsOn:compileTask) << {
System.out.println "building..."
}
build.gradle - summary
build.gradle is the file where we write the
build scripts
➔It consists of several tasks
➔However, we don't have to write all these
tasks manually.
➔Just like an IDE, different plugins have been
developed for all the build tasks in a specific
environment
➔
Gradle build system - plugin
Examples of Plug-in
Java Plug-in
➔
Android Plug-in
➔
Gradle plug-ins
The right plug-in is included through the
following text in the build.gradle file
➔
apply plugin: <plugin-name>
For Java - apply plugin: "java"
➔
For Android - 'com.android.application'
➔
Gradle & Android Studio
➔
➔
➔
Open a Project
Press F4 to go to the settings
We can add libraries and stuffs like this
Android App Basics - Layout - XML
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LinearLayout
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FrameLayout
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RelativeLayout
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TableLayout
An App to showcase Layout – A
Keypad Dialer
●
Example
Getting Notification through Toast
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Example
Android Activity LifeCycle
Android App Basics - Traversing
from one Screen to another
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We use Intent to do this
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We can pass data from one activity to another
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●
●
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One Activity (Screen) launches another activity (Screen) and
don't wait for the response
One Activity (Screen) launches another activity (Screen) and
wait for data sent back from the later
Intent Resolution
–
Explicit Intent Resolution
–
Implicit Intent Resolution
Example – ExperimentationWithIntent
Android App Basics – Declaring a Second Activity
<activity
android:name="com.somitsolutions.training.android.e
xperimentationwithintent.SecondActivity" >
<intent-filter>
<action
android:name="com.somitsolutions.training.android.experim
entationwithintent.TEST" />
<category
android:name="android.intent.category.DEFAULT" />
<data android:mimeType="text/plain" />
</intent-filter>
</activity>
Android App Basics – Traversing from one
activity to other
●
Explicit Intent Resolution
Intent i = new
Intent(getApplicationContext(),SecondActivity.clas
s);
●
Implicit Intent Resolution
Intent i = new Intent();
i.setAction("com.somitsolutions.training.android.e
xperimentationwithintent.TEST");
i.setType("text/plain");
Android App Basics – Passing Data from One
Activity to Other
●
●
Intent i = new
Intent(getApplicationContext(),SecondActivity.cl
ass);
i.putExtra("Key0", "This is the first String
Data...");
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i.putExtra("Key1", 10);
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startActivity(i);
Android App Basics – Passing Data from One
Activity to Other and waiting for the result
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●
Intent i = new
Intent(getApplicationContext(),SecondActivity.cl
ass);
i.putExtra("Key0", "This is the first String
Data...");
●
i.putExtra("Key1", 10);
●
startActivityForResult(i, mRequestCode);
Callback for The Returned Result
protected void onActivityResult(int requestCode, int resultCode,
Intent data) {
if(requestCode == mRequestCode){
if (resultCode == RESULT_OK){
String returnValue = data.getStringExtra("Key2");
Toast.makeText(getApplicationContext(), returnValue,
Toast.LENGTH_SHORT).show();
}
}
}
Extracting the Data in the Second Activity &
Returning the Result
String firstStringData =
returnIntent.getStringExtra("Key0");
int secondIntData = returnIntent.getIntExtra("Key1", 0);
returnIntent.putExtra("Key2", "This is the return result
from the called Intent");
setResult(RESULT_OK, returnIntent);
Toast.makeText(getApplicationContext(), "First Data:" +
firstStringData + "Second Data:"+
Integer.toString(secondIntData),
Toast.LENGTH_LONG).show();
finish();
Android UI - CheckBox
●
Example
Android UI - CheckBox
<CheckBox
android:id="@+id/checkbox"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/im_not_checked_string"
android:textSize="24sp"/>
Android UI - CheckBox
// Get a reference to the CheckBox
checkbox = (CheckBox) findViewById(R.id.checkbox);
// Set an OnClickListener on the CheckBox
checkbox.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// Check whether CheckBox is currently checked
// Set CheckBox text accordingly
if (checkbox.isChecked()) {
checkbox.setText("I'm checked");
} else {
checkbox.setText("I'm not checked");
}
}
});
Android UI - Spinner
●
Example
Android UI - Spinner
<Spinner
android:id="@+id/spinner"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textSize="24sp" />
Android UI - Spinner
Spinner spinner = (Spinner) findViewById(R.id.spinner);
// Create an Adapter that holds a list of colors
ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(
this, R.array.colors, R.layout.dropdown_item);
// Set the Adapter for the spinner
spinner.setAdapter(adapter);
// Set an setOnItemSelectedListener on the spinner
spinner.setOnItemSelectedListener(new OnItemSelectedListener() {
public void onItemSelected(AdapterView<?> parent, View view,
int pos, long id) {
Toast.makeText( parent.getContext(), "The color is " + parent.getItemAtPosition(pos).toString(),
Toast.LENGTH_LONG).show();
switch(pos){
case 0:
view.getRootView().setBackgroundColor(Color.RED);
break;
...................
...................
Android UI – Spinner – dropdown_item.xml
<?xml version="1.0" encoding="utf-8"?>
<TextView
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:textSize="24sp"
android:padding="5dp">
</TextView>
Android UI – Radio Group
●
Example
Android UI – Radio Group
<RadioGroup
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
>
<RadioButton
android:id="@+id/choice1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/choice_1_string"
android:textSize="24sp"/>
..........Other Radio Buttons................
</RadioGroup>
Android UI – Radio Group
// Define a generic listener for all three RadioButtons in the RadioGroup
final OnClickListener radioListener = new OnClickListener() {
@Override
public void onClick(View v) {
RadioButton rb = (RadioButton) v;
if(v.equals(choice1Red)){
v.getRootView().setBackgroundColor(Color.RED);
}
if(v.equals(choice2Green)){
v.getRootView().setBackgroundColor(Color.GREEN);
}
if(v.equals(choice3Blue)){
v.getRootView().setBackgroundColor(Color.BLUE);
}
}
};
............................
...........................
// Called when RadioButton choice1 is clicked
choice1Red.setOnClickListener(radioListener);
Android UI – Alert Dialog
●
Example
Thank you