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CHAPTER 30 Invoking a Service Services can be used by any application component that "hangs around" for a reasonable period of time. This includes activities, content providers, and other services. Notably, it does not include pure broadcast receivers (i.e., intent receivers that are not part of an activity), since those will get garbage collected immediately after each instance processes one incoming Intent. To use a local service, you need to start the service, get access to the service object, then call methods on that service. You can then stop the service when you are done with it, or perhaps let the service stop itself. Using remote services is somewhat more complex, which is why a discussion of it is reserved for The Busy Coder's Guide to Advanced <strong>Android</strong> Development companion volume. In this chapter, we will look at the client side of the Service/WeatherPlus sample application. The WeatherPlus activity looks an awful lot like the original Weather application – just a Web page showing a weather forecast: 377 Subscribe to updates at http://commonsware.com Special Creative Commons BY-SA 3.0 License Edition
The Ties That Bind Invoking a Service Figure 99. The WeatherPlus service client To start a service, one approach is to simply call startService(), providing the Intent specifying the service to start (again, the easiest way is probably to specify the service class, if it is your own service). Conversely, to stop a service started via startService(), call stopService() with the Intent you used in the corresponding startService() call. Once the service is started, you need to communicate with it. It could be that all the communication you need can be via the "extras" you package in the Intent. Or, if it is a local service that offers a singleton, you can reference the singleton. If, however, you implemented onBind() as shown in the previous chapter, there is a different way to get at the service – bindService(). When an activity binds to a service, it primarily is requesting to be able to access the public API exposed by that service via the service's binder, as returned by the service's onBind() method. When doing this, the activity 378 Subscribe to updates at http://commonsware.com Special Creative Commons BY-SA 3.0 License Edition
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The Busy Coder's Guide to Android D
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The Busy Coder's Guide to Android D
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GPS................................
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Using Selection Widgets............
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Embedding the WebKit Browser.......
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Styled Text........................
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query()............................
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You Make the Call!.................
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Handling API Changes...............
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your operating system does not supp
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The book does not cover in any deta
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• Places where you think we could
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The Big Picture • Keyboards, if t
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Content Providers The Big Picture C
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Projects and Targets To test your a
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Projects and Targets • libs/, whi
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Projects and Targets You also indic
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Projects and Targets In the preced
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Projects and Targets ... At the
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Projects and Targets You can create
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Projects and Targets • Only ask f
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Creating a Skeleton Application For
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Creating a Skeleton Application The
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Creating a Skeleton Application Fig
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Using XML-Based Layouts Android's S
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Using XML-Based Layouts Since this
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} public void onClick(View view) {
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Employing Basic Widgets • android
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Employing Basic Widgets Each widget
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Employing Basic Widgets For this pr
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Employing Basic Widgets The corresp
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Turn the Radio Up Employing Basic W
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It's Quite a View Employing Basic W
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Thinking Linearly Working with Cont
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Working with Containers • Set all
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Example Working with Containers Let
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} } } Working with Containers case
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Working with Containers If we toggl
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Working with Containers Positions R
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Working with Containers android:lay
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Working with Containers first in th
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Putting Cells in Rows Working with
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Working with Containers You can als
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Working with Containers
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Working with Containers the remaini
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Using Selection Widgets listbox. Th
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Using Selection Widgets android:lay
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Using Selection Widgets Then, rathe
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Using Selection Widgets the setDrop
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Using Selection Widgets Figure 24.
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Using Selection Widgets For example
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Using Selection Widgets TextView, w
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Using Selection Widgets something n
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Using Selection Widgets Figure 28.
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Using Selection Widgets • android
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Getting Fancy With Lists For exampl
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Getting Fancy With Lists A Dynamic
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Getting Fancy With Lists In the sam
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And you want happy users, right? Ge
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Using the Holder Pattern Getting Fa
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Getting Fancy With Lists super.onCr
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} Getting Fancy With Lists public v
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Getting Fancy With Lists So, let's
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Getting Fancy With Lists 1. While w
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Getting Fancy With Lists Figure 33.
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Getting Fancy With Lists So if we w
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Getting Fancy With Lists layout.set
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Getting Fancy With Lists public Rat
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Getting Fancy With Lists Details of
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Employing Fancy Widgets and Contain
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The Input Method Framework Of cours
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The Input Method Framework H
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The Input Method Framework Numbers
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The Input Method Framework android:
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The Input Method Framework Figure 5
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Applying Menus will appear, showing
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Applying Menus appropriate behavior
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Applying Menus @Override public voi
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Applying Menus Figure 56. The MenuD
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Applying Menus Figure 59. The same
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Applying Menus • You must
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Applying Menus In the layout XML sh
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Fonts 178 Subscribe
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The results? Fonts Figure 61. The F
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Fonts And, of course, Android's int
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android:layout_width="fill_parent"
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Embedding the WebKit Browser on the
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Embedding the WebKit Browser • go
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Running this activity gives us: Emb
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Showing Pop-Up Messages from the cu
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Showing Pop-Up Messages android:lay
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Showing Pop-Up Messages Figure 66.
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Dealing with Threads - merely creat
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Dealing with Threads super.onCreate
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Runnables Dealing with Threads If y
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Dealing with Threads AsyncTask, Gen
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import android.widget.ArrayAdapter;
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Dealing with Threads Since we elect
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Dealing with Threads Figure 68. The
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Handling Activity Lifecycle Events
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onPause() and onResume() Handling A
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What's Your Intent? Creating Intent
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Creating Intent Filters Basically,
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Narrow Receivers Creating Intent Fi
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Launching Activities and Sub-Activi
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} }); } } Launching Activities and
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Handling Rotation control over the
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Uri contact=null; Handling Rotation
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Handling Rotation Figure 74. The Ro
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Handling Rotation viewButton.setOnC
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Handling Rotation android:versionNa
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Handling Rotation To block Android
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Handling Rotation Note that Android
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Working with Resources • Strings,
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Working with Resources ((TextView)f
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@Override public void onCreate(Bund
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Got the Picture? Working with Resou
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Working with Resources Figure 79. T
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Working with Resources public void
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10px 1in Working with Resources In
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Working with Resources Different St
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Working with Resources • There ca
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Working with Resources 2. Next, And
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Using Preferences 3. getDefaultShar
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Using Preferences allowing users to
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Using Preferences Figure 81. The Si
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Using Preferences The fields for
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Using Preferences Any children of P
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Using Preferences Figure 85. The ch
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Philadelphia Pittsburgh Allentown/B
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Using Preferences Figure 88. Editin
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Managing and Accessing Local Databa
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Accessing Files application package
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} } Accessing Files .makeText(this,
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android:text="Close" /> Accessing
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Accessing Files openFileInput() to
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Leveraging Java Libraries • Size:
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Logging Development Tools Figure 11
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Development Tools Figure 114. DDMS
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Development Tools Figure 116. DDMS
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Development Tools Figure 118. Simul
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Put It On My Card Development Tools
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Taking the Default Handling Multipl
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Handling Multiple Screen Sizes •
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Handling Multiple Screen Sizes Thes
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Density-Based Sets Handling Multipl
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Handling Multiple Screen Sizes •
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Handling Multiple Screen Sizes size
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Handling Multiple Screen Sizes Repl
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Handling Multiple Screen Sizes scal
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Handling Multiple Screen Sizes R.st
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Handling Multiple Screen Sizes Figu
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Handling Multiple Screen Sizes />
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Handling Multiple Screen Sizes Now
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super.onCreate(savedInstanceState);
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Handling Multiple Screen Sizes In s
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Dealing With Devices Fortunately, s
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Dealing With Devices Market are tes
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Dealing With Devices The CLIQ also
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Not all devices will be this way. H
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The lessons to take from this: Hand
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Handling Platform Changes Note that
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Wrapping the API Handling Platform
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Handling Platform Changes } else {
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} } Handling Platform Changes publi
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You might also consider: Where Do W
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ContentManager.....................
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PreferenceCategory.................
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INTEGER............................
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getSpeed().........................
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setColumnShrinkable()..............
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android:paddingBottom..............
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