Referencing a library project
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If you are developing an application and want to include the shared code or resources from a library project, you can do so easily by adding a reference to the library project in the application project's Properties.
To add a reference to a library project, follow these steps:
- In the?Package Explorer, right-click the dependent project and select?Properties.
- In the?Properties?window, select the "Android" properties group at left and locate the?Library?properties at right.
- Click?Add?to open the?Project Selection?dialog.
- From the list of available library projects, select a project and click?OK.
- When the dialog closes, click?Apply?in the?Properties?window.
- Click?OK?to close the?Properties?window.
As soon as the Properties dialog closes, Eclipse rebuilds the project, including the contents of the library project.
Figure 2 shows the Properties dialog that lets you add library references and move them up and down in priority.
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Figure 2.?Adding a reference to a library project in the properties of an application project.
If you are adding references to multiple libraries, note that you can set their relative priority (and merge order) by selecting a library and using the?Up?and?Down?controls. The tools merge the referenced libraries with your application starting from lowest priority (bottom of the list) to highest (top of the list). If more than one library defines the same resource ID, the tools select the resource from the library with higher priority. The application itself has highest priority and its resources are always used in preference to identical resource IDs defined in libraries.
Declaring library components in the the manifest file
In the manifest file of the application project, you must add declarations of all components that the application will use that are imported from a library project. For example, you must declare any?<activity>,?<service>,?<receiver>,?<provider>, and so on, as well as<permission>,?<uses-library>, and similar elements.
Declarations should reference the library components by their fully-qualified package names, where appropriate.
For example, the?TicTacToeMain?example application declares the library Activity?GameActivity?like this:
<manifest> ... <application> ... <activity android:name="com.example.android.tictactoe.library.GameActivity" /> ... </application></manifest>
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