Managing ProjectsProjects act as containers for storing things
such as code and resource files. The SDK tools expect your projects
to follow a specific structure so it can compile and package your
application correctly, so it is highly recommended that you create
them with clipse and !DT or with the android tool on the command
line. There are three types of projects, and they all share the
same general structure "ut differ in function#Android Projects!n
!ndroid project is the container for your application$s source
code, resource files, and files such asthe !nt "uild and !ndroid
Manifest file. !n application project is the main type of project
and the contents are e%entually "uilt into an .apk file that you
install on a de%ice.Test ProjectsThese projects contain code to
test your application projects and are "uilt into applications that
run ona de%ice.Library ProjectsThese projects contain sharea"le
!ndroid source code and resources that you can reference in !ndroid
projects. This is useful when you ha%e common code that you want to
reuse. &i"rary projects cannot "e installed onto a de%ice,
howe%er, they are pulled into the .apk file at "uild time.'hen you
use the !ndroid de%elopment tools to create a new project, the
essential files and folders will "e created for you. There are only
a handful of files and folders generated for you, and some of them
depend on whether you use the clipse plugin or the android tool to
generate your project. !s your application grows incomplexity, you
might re(uire new kinds of resources, directories, and
files.!)D*+,D P*+-.TS!ndroid projects are the projects that
e%entually get "uilt into an .apk file that you install onto a
de%ice. They contain things such as application source code and
resource files. Some are generated for you "y default, while others
should "e created if re(uired. The following directories and files
comprise an !ndroid project#src/.ontains your stu" !cti%ity file,
which is stored at src/your/package/namespace/ActivityName.java.
!ll other source code files /such as .java or .aidl files0 go here
as well.bin/+utput directory of the "uild. This is where you can
find the final .apk file and other compiled resources.jni/.ontains
nati%e code sources de%eloped using the !ndroid )DK. 1or more
information, see the !ndroid )DKdocumentation.gen/.ontains the -a%a
files generated "y !DT, such as your R.java file and interfaces
created from !,D& files.assets/This is empty. 2ou can use it to
store raw asset files. 1iles that you sa%e here are compiled into
an .apk file as3is, and the original filename is preser%ed. 2ou can
na%igate this directory in the same way as a Page 1 of 91typical
file system using 4*,s and read files as a stream of "ytes using
the AssetManager. 1or example, this is a good location for textures
and game data.res/.ontains application resources, such as drawa"le
files, layout files, and string %alues. See !pplication *esources
for more information.anim/1or 5M& files that are compiled into
animation o"jects. See the !nimation resource type.color/1or
5M& files that descri"e colors. See the .olor 6alues resource
type.drawable/1or "itmap files /P)7, -P7, or 7,10, 83Patch image
files, and 5M& files that descri"e Drawa"le shapes or Drawa"le
o"jects that contain multiple states /normal, pressed, or focused0.
See the Drawa"le resource type.layout/5M& files that are
compiled into screen layouts /or part of a screen0. See the
&ayout resource type.menu/1or 5M& files that define
application menus. See the Menus resource type.raw/1or ar"itrary
raw asset files. Sa%ing asset files here instead of in the assets/
directory only differs in the waythat you access them. These files
are processed "y aapt and must "e referenced from the
applicationusing a resource identifier in the R class. 1or example,
this is a good place for media, such as MP9 or+gg files.values/1or
5M& files that are compiled into many kinds of resource. 4nlike
other resources in the res/ directory, resources written to 5M&
files in this folder are not referenced "y the file name. ,nstead,
the 5M& element type controls how the resources is defined
within them are placed into the R class.xml/1or miscellaneous
5M& files that configure application components. 1or example,
an 5M& file that defines aPreferenceScreen,
AppWidgetProviderInfo, or Searcha"ility Metadata. See !pplication
*esources for more information a"out configuring these application
components.libs/.ontains pri%ate li"raries.AndroidManifest.xmlThe
control file that descri"es the nature of the application and each
of its components. 1or instance, it descri"es# certain (ualities
a"out the acti%ities, ser%ices, intent recei%ers, and content
pro%iders: whatpermissions are re(uested: what external li"raries
are needed: what de%ice features are re(uired, what !P, &e%els
are supported or re(uired: and others. See the !ndroidManifest.xml
documentation for more informationproject.propertiesThis file
contains project settings, such as the "uild target. This file is
integral to the project, so maintain it in asource re%ision control
system. To edit project properties in clipse, right3click the
project folder and selectProperties.local.properties.ustomi;a"le
computer3specific properties for the "uild system. ,f you use !nt
to "uild the project, this contains the path to the SDK
installation. estroy;< call"ack, so it$s important you use
on(top;< to release resources that might leak memory.!lthough
the on%ause;< method is called "efore on(top;estroy;< method
for your Activity. irectory;irectory;< for files that are shared
orget3xternal"iles>ir;< for files that are pri%ate to your
app, it$s important that you use directory names pro%ided "y !P,
constants like >@R39TDRG0%@9TER3(. These directory names ensure
that the files are treated properly "y the system. 1or instance,
files sa%ed in >@R39TDRG0R@F/TDF3( are categori;ed "y the system
media scanner as ringtones instead of music.M4*2 1* SP!.,f you know
ahead of time how much data you$re sa%ing, you can find out whether
sufficient space is a%aila"le without causing an @D3xception "y
calling get"ree(pace;< or getTotal(pace; * +entryid+Bpublic
static final (tring 9D1EMF0FAM30T@T13 * +title+Bpublic static final
(tring 9D1EMF0FAM30(E8T@T13 * +subtitle+B...??.*!T ! D!T! 5 +
@FT3/3R %R@MARG Q3GA+ 5"eed3ntry.9D1EMF0FAM303FTRG0@> 5
T3CT0TG%3 5 9DMMA0(3% 5"eed3ntry.9D1EMF0FAM30T@T13 5 T3CT0TG%3 5
9DMMA0(3% 5... // Any ot$er options for t$e 9R3AT3 command+
313T303FTR@3( *+>RD% TA813 @" 3C@(T( + 5
"eed3ntry.TA8130FAM3B-ust like files that you sa%e on the de%ice$s
internal storage, !ndroid stores your data"ase in pri%ate disk
space that$s associated application. 2our data is secure, "ecause
"y default this area is not accessi"le to other applications.!
useful set of !P,s is a%aila"le in the (T1iteDpen&elper class.
'hen you use this class to o"tain references to your data"ase, the
system performs the potentially long3running operations of creating
and updating the data"ase only when needed and not during app
startup. !ll you need to do is call getKritable>atabase;<
orgetReadable>atabase;atabase;< in a "ackground thread, such
as with AsyncTask or @ntent(ervice.To use (T1iteDpen&elper,
create a su"class that o%errides the on9reate;b&elper extends
(T1iteDpen&elper =// @f you c$ange t$e database sc$emaA you
must increment t$e database version.public static final int
>ATA8A(30)3R(@DF * -Bpublic static final (tring >ATA8A(30FAM3
* +"eedReader.db+Bpublic "eedReader>b&elper;9ontext
context< =super;contextA >ATA8A(30FAM3A nullA
>ATA8A(30)3R(@DFatabase db<
=db.exec(T1;(T109R3AT303FTR@3(atabase dbA int old)ersionA int
new)ersion< =// T$is database is only a cac$e for online dataA
so its upgrade policy is// to simply to discard t$e data and start
overdb.exec(T1;(T10>313T303FTR@3(atabase dbA int old)ersionA
int new)ersion< =onEpgrade;dbA old)ersionA
new)ersionb&elper;get9ontext;A idatabase;efine a
projection t$at specifies w$ic$ columns from t$e database// you
will actually use after t$is Nuery.(tringUV projection *
="eed3ntry.0@>A"eed3ntry.9D1EMF0FAM30T@T13A"eed3ntry.9D1EMF0FAM30E%>AT3>A...?BPage
$+ of 91// &ow you want t$e results sorted in t$e resulting
9ursor(tring sortDrder *"eed3ntry.9D1EMF0FAM30E%>AT3> 5 +
>3(9+B9ursor c * db.Nuery;"eed3ntry.TA8130FAM3A// T$e table to
NueryprojectionA // T$e columns to returnselectionA// T$e columns
for t$e K&3R3 clauseselectionArgsA// T$e values for t$e
K&3R3 clausenullA // donMt group t$e rowsnullA // donMt filter
by row groupssortDrder // T$e sort order(tring selection *
"eed3ntry.9D1EMF0FAM303FTRG0@> 5 + 1@Q3 6+B(tringUV
selectionArgs * = (tring.valueDf;row@d< ?Bint count *
db.update;"eedReader>b&elper."eed3ntry.TA8130FAM3AvaluesAselectionAselectionArgs
