Android 2: A First Project

1. Android 2: A First Project Kirk Scott

3. 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

4. 2.1 Creating a New, Example Android Application Project in Eclipse

5. These overheads give a general overview of what is involved in getting a sample application to work—without even looking at its code, how it works, or what Android features it is making use of or depends on • This is the initial monkey work mentioned in the previous set of overheads

6. These overheads are based on the initial example app that is given in the tutorial on the Android developer’s Web site • If you discover that something in the overheads doesn’t seem to work, it means you can go directly to the tutorial for additional information

7. 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

9. In the first box, type in the following: • My First App • The other boxes will auto-complete as shown in the following screenshot • (If the other boxes don’t auto-complete, this is the first stage where you will have to go fish)

11. If things auto-completed as hoped, then you click the Next > button • I will not show the next screenshots for the wizard • Just keep on accepting the defaults and taking Next until you reach the Finish option • Notice how this is an area where you’re just doing monkey work • God knows what all of the options mean at this point

12. Once you click finish “things will happen” • They may happen slowly • I have a reasonably powerful machine and it takes things a while to happen • There is a progress bar at the bottom which gives you some indication of what’s going on

13. The initial Welcome screen may remain visible • If so, it covers up what has happened • Minimize anything in the way, and with luck, what you will see in the Eclipse environment will look more or less like the screenshot on the following overhead

15. There are several things to notice in this screenshot • The simplest and most reassuring 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 using the defaults, this Hello World layout is provided by default

16. Obviously you’re not looking at code • The name of the file that is being shown has an XML extension • What you’re seeing is the layout of the output of the app • What you’re seeing is a representation of the layout as provided in the development environment • This is not the output showing in the emulator

17. 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 • The toolbar happens to have disappeared • It’s not a big cause for concern • You can cause it to appear again or you can access the tools through the menu

18. 2.2 Creating a Virtual Device, an Emulator

19. 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

21. Click the New button to create an Android Virtual Device • The window shown in the screenshot on the following overhead comes up

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

25. I tried using various devices • For initial test purposes I finally settled on the device at the bottom of the list • My theory was that emulation for older, simpler devices might work better or faster than for newer devices • On the following overhead the form is shown filled out with representative values for that simple device

27. Using Snapshot • Another mystery: • Certain reference sources waffle on the desirability of 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, but again, for the first time, try it without Snapshot

28. Warning • Here is an example of what can go wrong • I also tried making a virtual device that was a Nexus tablet (the real hardware I’m working with) • The memory option defaulted to a RAM value of 1024 • Unfortunately, when I continued with that value of 1024, I got a mystery error

29. My Web search informed me that if I changed the RAM value to 512, things should be OK • For the device I’ve chosen to illustrate with, I took memory size values of 256 • For whatever reason, these values worked, and for the time being, that’s good enough for me

30. 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

32. 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

33. 2.3 Running an App on the Emulator in Eclipse • There are several different ways of running an app in the emulator • Later on you will find out that you can create run configurations and debug configurations which are linked to a project • This is a fine way of doing business, but more complicated than necessary initially

34. Starting the emulator can take a lot of time • Trying to run the app and having that process start the emulator doesn’t seem to be the best plan • The alternative is to start the emulator and then run the app in it • This second approach is a better way to do it initially

35. 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

37. If you click the Start button the following screen should appear • This is the magic moment • Click Launch

39. After clicking launch, you should see the screen with the progress bar shown on the following overhead • So far so good

41. 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

43. Even If Things are Going OK, This is the Painful Part • What you need now is patience (potentially a lot of it) and faith • The Android message on the emulated device 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 • Find something to kill a little time with, because a watched pot never boils

44. Edging Towards Success • 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

46. 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

48. 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

50. Running the Project in the Emulator • If you want to run the project (without setting up run or debug) configurations, 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