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Islamic University of Gaza Eng. Jehad Aldahdooh

Faculty of Engineering Mobile Computing

Computer Engineering Dept. Android Lab

To create a new Android Project follows the steps:

1. Open Eclipse.

2. Click the menu File New Android Application Project

Lab 1: Getting Started With Android Programming

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3. Name the project : In this stage, as shown below there are exist three names described as:

Application Name

Shown in Play Store and Settings .Usually same as Project Name.

Project Name

Eclipse project name. Follow naming convention you use for Eclipse. Not used

elsewhere.

Package name

Apps on a particular Android device must have unique packages, so use

com.yourCompany.project

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Target Build SDK

The Android version used to build/compile your project. This can be any version,

but the safest option is to make it match the minimum SDK below.

Minimum Required SDK

The Android version that you want to run on.

4. Click Next

5. Configure Launcher Icon

Purpose

To choose the picture displayed on the Android device, that, when clicked,

launches the app.

Defaults

Use defaults for development and testing. Just press “Next”.

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6. Choose “Blank Activity”

Options for Blank Activity:

Activity Name

Name of “main” Java class. This is the class you will edit first. Class name often

corresponds to project name.

Layout Name

Base name of XML file in res/layout folder. Used to give layout to app. often

just called “main”. Will be referred to in main Java class with

R.layout.layout_name.

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Anatomy of an Android Application

Source Code

Java files auto-

generated by ADT Version of the

library you had

chosen

Anything stored in the

'assets' folder has to

be accessed in the

classic 'file'

manipulation style

Resources that

your application

may need

Value type

resources,

such as string

and integer

constants

Use to construct

user interfaces

Hold image and

animation files that

you can use in your

application.

Contains all the

information about the

application

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First: On the Emulator

Before we can run the application, we need to setup an Android Vitual Device(AVD), or

emulator, to run it on:

Select the menu Window -> "Android SDK and AVD Manager".

Select Virtual Devices on the left hand side.

Click the New... button.

Give your AVD a name.

Select the target build that we would like to run the application on

Click Create AVD and close out the SDK/AVD Manager.

We're now ready to run our application.

Select the menu Run -> Run.

Note: The emulator may take a long time to start up.

Note: Another way to run your application is to right-click on the project in the

Package Explorer, then select Run As -> Android Application.

Run “Hello World” on the Emulator and Phone

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Second: On a Physical Device

Project Modifications

From the Package Explorer, double-click the file AndroidManifest.xml.

Select the tab labeled AndroidManifest.xml along the bottom.

Add android:debuggable="true" to the inside of the opening <application> tag.

Save the file and close it.

Phone Modifications

o Select Settings -> Applications -> Development.

o Enable the USB debugging option

Ensure the device is properly connected. Run the application as you would normally.

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1. Java-based

Use Java to define Strings, lay out window, create GUI controls, and assign event

handlers. Like Swing programming.

1. XML-based

Use XML files to define Strings, lay out window, create GUI controls, and assign

event handlers. The Java method will read the layout from XML file and pass it to

setContentView.

2. Hybrid

Use an XML file to define Strings, layout window and create GUI controls. Use Java

to assign event handlers.

1. Java-Based Approach: Template Approach

Use Java to define Strings, layout window, create GUI controls, and assign

event handlers.

Advantages

Familiar to Java desktop developers. Like approach used for Swing, SWT, and

AWT.

Good for layouts that are dynamic (i.e., that change based on program logic).

Disadvantages

Harder to maintain.

Not generally recommended except for dynamic layouts.

But still acceptable for App Store. Whatever works best for your programmers

and your app. No code police.

Three Main Approaches in Android Programming

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OnClickListener is a public inner class inside View. But, as long as you import

android.view.View.OnClickListener, you use it just like a normal class. And, remember that

Eclipse helps you with imports: just type in the class name.

2. XML-Based Approach: Template Approach

Use XML files to define Strings, layout window, create GUI controls, and

assign event handlers.

Define layout and controls in res/layout/main.xml

Define Strings in res/values/strings.xml

Advantages

Easier to maintain

Can use visual layout editor in Eclipse

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Disadvantages

Works poorly for dynamic layouts

3. Hybrid Approach: Template

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Activity: Much like a Form for a web page, activities display a user interface for the

purpose of performing a single task. An example of an Activity class would be one which

displays a Login Screen to the user.

Create the Activity Class

create a new class that extends android.app.Activity class and implements

android.view.View.OnClickListener interface.

Add a method with the following signature: public void onCreate(Bundle

savedInstanceState) .

o This method will be called when the Activity starts and is where initialization of local

and member data will be done.

Inside this method perform the following:

Activity Class

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o make a call to super.onCreate(savedInstanceState)

This should always be done and is to ensure that any necessary parent class

initializations are performed.

o make a call to this.setContentView(R.layout.activity_main)

When you created the XML layout file earlier, the Android Eclipse Plugin

automatically added a static constant to the static R.layout class in the R.java

file under the /gen folder. This constant variable has the same name of the file

and it's value is used to identify the layout file.

This call tells Android to create a screen based off of the layout file.

o Make a call to this.findViewById(R.id.button) and set your Button member variable

equal to the return value.

Implement the OnClickListener interface by creating a method stub with the following

signature: public void onClick(View v) .

The Activity base class defines a series of events that govern the life cycle of an

activity. The Activity class defines the following events:

onCreate() — Called when the activity is first created

onStart() — Called when the activity becomes visible to the user

onResume() — Called when the activity starts interacting with the user

onPause() — Called when the current activity is being paused and the previous

activity is

being resumed

onStop() — Called when the activity is no longer visible to the user

onDestroy() — Called before the activity is destroyed by the system (either

manually or by the system to conserve memory

onRestart() — Called when the activity has been stopped and is restarting again

Android Lifecycle

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1. Run the application .

2. When the activity is first loaded, you should see something very similar to the following in

the LogCat window

In the onCreate() event

In the onStart() event

In the onResume() event

3. If you click the Back button on the Android emulator, the following is printed:

In the onPause() event

In the onStop() event

In the onDestroy() event

4. Click the Home button and hold it there. Click the Activities icon and observe the following:

In the onCreate() event

In the onStart() event

In the onResume() event

5. Click the Phone button on the Android emulator so that the activity is pushed to the

background.Observe the output in the LogCat window:

In the onPause() event

In the onStop() event

6. Notice that the onDestroy() event is not called, indicating that the activity is still in memory.

Exit the phone dialer by clicking the Back button. The activity is now visible again. Observe the

output in the LogCat window:

In the onRestart() event

In the onStart() event

In the onResume() event