CNT5517/CIS4930-Lab 1 Solved

CNT5517/CIS4930 Mobile Computing  

Lab 1 - Android Getting Started and The APISearchAndroid App 


INTRODUCTION 

In this lab, you will learn how to setup the Android development environment and install all necessary developer tools on your computer in preparation for writing applications for Android. You will also learn how to use basic development tools to develop Android applications, from project creation to installation.  

 

GOALS 

●     Setup the Android development environment (Install Android Studio). 

●     Create a "Hello World" Android application and run it on the Android Virtual Device (emulator). 

●     Understand the basic components of an Android project. 

●     Download and import the APISearchAndroid application and run it on the emulator. 

●     Make specific changes to the APISearchAndroid application.  

 

1.   Setting Up the Android Development Environment
 

To set up the development environment for Android, you first need to install Android

Studio, which can be found at https://developer.android.com/studio/index.html The download page also features the steps needed to install Android Studio. What follows is a quick summary of the steps. 

 

Windows  

 

1)    Download the executable from the official page.

2)    Run the installer

3)    Follow the prompts. You can leave all of the options as their defaults.

4)    Run Android Studio and follow the prompts. You can leave all of the options as their defaults. Notice: Make sure that you select the Android Emulator Image option when installing the SDK.

 

Mac 

 

1)    Download the dmg from the official page.

2)    Mount the image and drag Android Studio into the Applications Folder

3)    Run Android Studio and follow the prompts. You can leave all of the options as their defaults. Notice: Make sure that you select the Android Emulator Image option when installing the SDK.

 

Linux 

 

1)    Download the Android Studio archive from the official page.

2)    Depending on your distro, use your package manager to install Android Studio’s needed dependencies (libc6 libncurses5 libstdc++6 lib32z1 libbz2-1.0). Notice: If your machine is 64-bit, you must install the 32-bit versions of the aforementioned libraries

3)    Unarchive Android Studio to your installation folder of choice (Google recommends /opt) and run android-studio/bin/studio.sh. You can leave all of the options as their defaults. Notice: Make sure that you select the Android Emulator Image option when installing the SDK.

 

2.   Creating and Running Hello World Application
 

In this lab, we only require you to be able to run your app on a device emulator (Android Virtual Device or AVD). Of course, you should be able to run your app on an actual Android device if you have access to one, but you are not required to. To set up an AVD: 

●      Select the menu Tools => Android => AVD Manager, or click on the phone shaped icon in the toolbar. (Notice: If you have followed the installation steps, then a device should already be listed as Nexus 5X API 25 x86, or later devices) 

 

If you do not see any devices, then follow these steps to create an Android Emulator. 

●      Open the Android Virtual Devices window. 

●      Click the Create Virtual Device button (located in the bottom left). 

●      Select Nexus 5X. 

●      On the next screen, select the target build that you would like to run the application on, e.g., "Nougat". 

●      Click Next and then Finish to terminate the SDK/AVD Manager Window. 

 

Now, you have created an Android emulator. Next, create the Hello World app: 

●      Click the menu File -> New -> Android Application Project. 

●      Name the project “Hello World” and set location of project, or use default location 

●      Check the latest release/API level from the Build Target SDK list, and leave other settings as default. 

●      On the next screen, you can select an activity template from which to begin building your app. For this project, select Empty Activity and click Next. 

 By selecting Empty Activity, a Hello World app is automatically generated.☺ How convenient!! The ADK is doing the assignment for you     

●      Both the activity and its associated layout must be named. Leave the default selections and click Finish. 

Now, run Hello World App on the Emulator: 

●      Select Run => Run App in the toolbar, then select your AVD and click OK. 

●      Select or make sure you are under Android Application. Then type in or browse and select your project in the Android tab. Then in Target tab, choose the emulator you just created. Click Run.  

The emulator will be launched (after some delays, so be patient). If all goes well, you should see the following result. 

 

Congratulations, you've just created and ran your first Android Application!  (Buy yourself an Oatmeal cookie) 

3.   Directories and Files in an Android Project
 

Now let us look at the workspace of the Hello World app and get to know the useful directories and files in an Android project. Double click your HelloWorld project in the Package Explorer to expand it, if it is not already expanded. You should see the following directories:  

●      src/: directory for app’s main source code (includes Activity class) 

●      AndroidManifest.xml: describes all metadata about the app that the Android OS will need to run the app properly. 

o     Package name used to identify the application. 

o     List of Activities, Services, Broadcast Receivers, and Content Provider classes and all of their necessary information, including permissions. o Libraries and API levels that the application will use. 

●      res/: directory for app resources. The main content categories include drawables, layouts, and values.  

o     drawable/: directory that holds image and animation files designed for screens with different densities. 

o     layout/: directory for files that define your app's user interface. It already contains a file called activity_main.xml which defines the user interface for your HelloWorld Activity class. Double clicking on this file will open up the Android UI Editor that you can use to help generate the xml layout files. 

o     values/: directory where you define (in XML) your globally used colors, dimensions, strings and styles.  

●      gen/: directory where code is generated for all the resources defined in your res folder. It already contains one file called "R.java" which is a special static class that is used for referencing the data contained in your resource files. 

●      assets/: directory where stores miscellaneous files you need to access in your code as raw data. Unlike files in the res folder, the only way to load something from assets is to programmatically open it as a file. 


4.   Activities
An Activity is an application component that provides a screen with which the user and the application can interact. For instance the user may interact with the application by dialing a phone number, taking a photo shot, sending an email, or viewing a map. Each activity has an associated Activity Layout (in XML) that is provided as a window with user interface widgets. 

An application usually consists of multiple activities that are loosely bound to each other. Typically, one activity in an application is specified as the "main" activity, which is presented to the user when launching the application for the first time. Each activity can then start another activity using Intent in order to perform different actions. Each time a new activity starts, the previous activity is stopped, but the system preserves the activities in a stack (the "back stack"). Activities must be declared in the manifest file in order for them to be accessible to the system. Creating an activity in a project through File => New => Activity, which will automatically create a declaration for that activity in the manifest file. However, an activity can also be declared (or a declaration edited) by opening the manifest file and adding or editing an <activity> element as a child of the <application> element.  

For more information about how to implement an Activity, how to create and use Intent, how to implement user interface layout for an Activity, how to declare the Activity in the Manifest file and so forth, read Android developer webpage.  

5.   Download and Import the APISearchAndroid App
 

●      Download the source code of the APISearchAndroid app covered in the Android lecture from http://www.cise.ufl.edu/~helal/classes/s17/APISearchAndroid.zip 

●      Unpack the ZIP file and copy/paste the APISearchAndroid folder to your Android Studio workspace (i.e., the folder where your Hello World app is located).  

●      Next, to open the APISearchAndroid project into your Android Studio project, click the menu File => Open 

●      In this screen, browse and select the directory where you just saved your APISearchAndroid folder. Click OK, then Next, and then Finish. 

 

Now you have opened the APISearchAndroid App in your Android Studio. 

6.   Making Changes to APISearchAndroid App
 

In this project, you are required to make following two changes to the APISearchAndroid application you just imported. 

 

1.    A user can choose any result from the list of the returned results by clicking on it. When the user clicks a particular result, it will navigate to a new screen which displays the user selected result information (title, text, image).

To achieve 1, you will need to create a new Empty Activity (name it

ResultDisplayActivity) to display the information about the user selected result. Then you will need to add new function to the APISearchActivity class to be able to parse the user selected item from the user interface and initiate the ResultDisplayActivity (So now you are doing Java programming). Finally, you will have to reconfigure the application Manifest to use your new name retrieval Activity on startup. 

2.    Add back button functionality to the layout of the result display (result.xml). This button allows the user to finish the current activity and load the previous screen view (i.e., from result to the main layout) by clicking on it. Note that, at any screen (e.g., main layout) that is loaded by pressing back button, it should still be able to perform its function properly (e.g, in the main view, user is still able to click on any result from the list to navigate to a new screen where its info is displayed).