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Android 2: A First Project

Kirk Scott

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• 2.1 Creating a New, Example Android Application Project in Eclipse

• 2.2 Creating a Virtual Device, an Emulator• 2.3 Running an App on the Emulator in Eclipse• 2.4 Running the Project on an Attached

Device Instead of an Emulator

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2.1 Creating a New, Example Android Application Project in Eclipse

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• These overheads give a general overview of getting a sample application to work

• They do not look at its code, how it works, or what Android features it is making use of or depends on

• The example is based on the first app given in the tutorial on the Android developer’s Web site

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A New Android Application

• In the Eclipse menu take the option File, New, Android Application Project

• The result of this is shown in the screenshot on the following overhead

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• In the first box, type in the following:• My First App• The other boxes will auto-complete as shown

in the following screenshot

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• If things auto-completed, then you click the Next > button

• The next screenshots for the wizard will not be shown

• Just keep on accepting the defaults and taking Next until you reach the Finish option

• Do not worry about what all of the options/defaults mean

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• At the end of the process, the system will take certain actions

• There is a progress bar at the bottom which gives some indication of what’s going on

• You may have to wait a certain amount of time

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• The initial Welcome screen may remain visible• If so, it will cover up what has happened• Minimize anything in the way• What you expect to see is something more or

less like the screenshot on the following overhead

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• There are several things to notice in this screenshot

• The simplest is that if you can actually read the fine print, you will see that My First App is a Hello World app

• Whenever a new app is created in Android using the defaults, this Hello World layout is provided by default

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• You’re not looking at code• The name of the layout file that is being

shown has an XML extension• What you’re seeing is the layout of the output

of the app

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• It is important to understand that at this point you are not looking at emulation of a running app

• What you’re seeing is a representation of the layout as provided in the development environment

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• You might notice that this screenshot of the editor doesn’t look quite like the one given earlier

• It doesn’t show the tools mentioned in the previous set of overheads, but it’s not exactly the same

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• The toolbar happens to have disappeared• It’s not a big cause for concern• In the menu under the Window option you

can choose to hide or show the toolbar• If the toolbar is hidden you can access the

tools through the menu

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2.2 Creating a Virtual Device, an Emulator

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Running the Project on a Virtual Device, an Emulator

• If you want to run the project using the emulator, you need to use the Android Virtual Device Manager to create a new virtual device

• If you take the Android Virtual Device Manager tool (or menu option) you should arrive at something similar to the screenshot shown on the following overhead

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• Click the New button to create an Android Virtual Device

• The window shown in the screenshot on the following overhead comes up

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• It’s shown on the following overhead with the drop down list for Device expanded

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• For initial test purposes you might choose to use the device at the bottom of the list

• This is the simplest device with the fewest resources

• On the following overhead the form is shown filled out with representative values for that simple device

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Using Snapshot

• Certain reference sources recommend using the Snapshot option

• If you do select Snapshot and then make other changes, you may have troubles later

• Without Snapshot things might run more slowly

• It is best initially not to use Snapshot

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Warning

• Here is an example of what can go wrong• Suppose you wanted to emulate a Nexus 7

device• The memory option may default to a RAM

value of 1024

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• Unfortunately, this can lead to an error where it may not even be clear that the RAM size is what is causing the error

• A Web search on the error will inform you that if the RAM value to 512, things should be OK

• Using the simplest device as an example, a memory size of 256 will work

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Continuing with Virtual Device Creation

• Once you’ve got the parameters set, click on OK

• The system can drag on for a noticeable amount of time creating the virtual device

• Successful completion is indicated by the appearance of the device in the list as shown in the screenshot on the following overhead

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• There is no final OK step after virtual device creation

• You’re done—and you have to close this window

• If you just minimize it, it sits there but is still the active window

• To go on from here, close this window

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2.3 Running an App on the Emulator in Eclipse

• There are several different ways of running an app in the emulator

• It is possible to create run and debug configurations which are linked to a project

• This is not necessary for an initial example

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• Starting the emulator can take a lot of time• Trying to run the app and having that process

start the emulator does not work well• It is better to begin the process of starting the

emulator• Wait patiently until it is running• Then test the app on it

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Starting the Emulator

• The Android Virtual Device screen is shown again on the following overhead with the created virtual device in it

• The screenshot shows the device as being selected and you’ll note a Start… button on the right hand side

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• If you click the Start button the following screen should appear

• From here, click the Launch button

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• After clicking launch, you should see the screen with the progress bar shown on the following overhead

• So far so good

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• Even before the previous screen goes away, or at the very least, as soon as it finishes, you should see the emulator on the screen

• It’s conceivable that you’ll have to close some things to find it

• It may be hidden• In any case, the initial stage of launch shouldn’t

take a long time, and this is what you should see

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Now You Have to Wait Patiently

• The Android message on the emulated device shown in the previous screen shot will flash white for an indeterminate period of time

• The emulator is still launching• As long as that process is going on, there’s

nothing else that you should do except wait

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• Eventually, with good luck, the emulator will look as shown on the following overhead

• In the screenshot that is shown, the emulator screen is grayed out

• The emulator has started, but it’s taken so long that it is mimicking a device that has fallen asleep

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• If your emulator is grayed out, click and drag over the emulator screen with the mouse

• This should wake it up, as shown on the following overhead

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• Click on the circle as directed• If the apps are shown, as they are in the

following screenshot, you have been successful

• The emulator has been launched and is running

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Running the Project in the Emulator

• If you want to run the project, you need a source file for the project open in the Eclipse environment

• The screenshot on the following overhead shows the explorer on the left tracing the path to the MyFirstApp.java file, with that file open in the editor in the middle

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• To prepare for running a project, you need to build or clean it

• In the menu you could take Project, Build All• A more thorough approach would be to take

the Project, Clean… option• This leads to the screen shot on the following

overhead

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• After the build or the clean is complete, you can run from the menu or the toolbar

• In the menu under Run there is a Run option• The run tool in the toolbar is a small green

circle with a right facing, white arrowhead in it• If you use the tool, there’s no need to take the

dropdown option and select from the choices there

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• The first time you to try to run it, you may get another dialog box asking what kind of thing you’re trying to run

• You’re given a list of choices, and the choice you want to make is “Android application”

• This dialog is shown on the following overhead

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• Remember that you started the emulator earlier• It is covered up by the development environment• After choosing the run type, find the emulator

again• Find it again• You may still have to wait a while for the app to

start, but with luck, you’ll see what’s shown in the screen shot on the following overhead

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• Click and drag over the emulator screen, and it comes to life, as shown on the following overhead

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• The phrase “Hello World!” is what was shown in the layout for the app in the development environment

• This is the output that the app is designed to produce

• We have now seen the app successfully demonstrate this output in the emulator

• This is not just the design; it’s the result of running code

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2.4 Running the Project on an Attached Device Instead of an Emulator

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• Being able to use the emulator is important—but it can occasionally be problematic

• Being able to run an app on an actual attached device is no less important—and it can be no less problematic

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• If you haven’t yet run a homemade app on your device, there are essentially 3 steps:

• 1. Getting the Device Ready• You have to get into developer mode so that

you it’s possible to transfer the app to the device

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• 2. Downloading and Installing the Driver• You need a USB driver in order to transfer

through a USB port• 3. Running the App on the Device• Then you can run the app on the device

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• For reference purposes, these overheads were prepared with the following:

• Windows 7• Eclipse, as already described• A Nexus 7 tablet• The fact that it was the Nexus 7 tablet is

relevant to the specific instructions for getting the device ready

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Getting the Device Ready

• On the running device, go to the App screen• Tap on Settings• Under System, find About tablet• Tap Build number 7 times• When you return from doing this you should

find Developer options under System

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• Take Developer options• Under Debugging, enable USB debugging• You can now connect the device to your

system using a USB cable

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Downloading and Installing the Driver

• For information on the Nexus 7 USB driver, if you want any, go to the Android Web site:

• http://developer.android.com• A search on “USB driver” will take you to a

page that has information on the driver• The driver is only necessary when developing

in a Windows environment

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• You have a choice on getting the driver• Either you can download from this page• Or you can use the Android SDK Manager

from the ADT bundle in Eclipse• If you’re following this set of overheads and

not using your own development environment, using the SDK Manager is easier

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• Using the manager is so easy, there’s not much to say about it

• Click on the Android SDK manager tool in the Eclipse environment

• Find the line for the driver• Click and follow any instructions

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What Can Be Problematic

• The premise of this section is that you are trying to set this up on your own machine

• Various versions of Windows will sometimes try to use a generic Windows driver instead of the Google driver

• This can be a serious problem• On some systems, it appears to be impossible to

prevent Windows from doing this• If that happens, you will be unable to run an app on

an attached device

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• It may also be possible to manually replace a Windows driver with the Google driver

• Here is a brief list of steps for downloading and installing the driver:

• Note which folder the driver is saved in• Right click on the “computer” icon on your machine• Take the Manage option• Select the Device Manager on the left• Find and expand the Other devices

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• Find the Nexus 7 device in the list• You may find the Nexus 7 device somewhere

else depending on your situation• When you find the Nexus 7 device, right click

on it• Take the Update Driver Software… option• Follow the directions and browse to the

location where the driver was saved to

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Running the App on the Device

• The assumption is that you successfully installed the driver and your device is attached with a USB cable

• Open your app in Eclipse• Take the Run tool or the Run option in the menu• This should cause the Android Device Chooser to

appear on the screen, with the Nexus 7 device in the list

• A screen shot is shown on the following overhead

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• Select your device and click OK• The app should run on your device• In addition to running, it will be installed on

the device• If you go to the apps screen you’ll find the

little green Android icon with the name of the app and you can run it from there in the future

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Summary and Mission

• This is the end of the description of the first project

• As noted, it was only about nuts and bolts• The presentation had nothing to do with code

or the components of the app• Those topics will be pursued in the following

sets of overheads

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• You have two missions:• 1. Get “Hello World” to work on an emulated

virtual device in whatever development environment you’re using

• 2. Get “Hello World” to work on a real attached Android device

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The End