1 Creating a New Android Project
The first step in the application development process is to create a new project within the Android Studio environment. Begin, therefore, by launching Android Studio so that the “Welcome to Android Studio” screen appears The Project location setting will default to a location in the folder named AndroidStudioProjects located in your home directory and may be changed by clicking on the button to the right of the text field containing the current path setting. Click Next to proceed. On the form factors screen, enable the Phone and Tablet option and set the minimum SDK setting to API 8: Android 2.2 (Froyo).
The reason for selecting an older SDK release is that this ensures that the finished application will be able to run on the widest possible range of Android devices. The higher the minimum SDK selection, the more the application will be restricted to newer Android devices.This outlines the various SDK versions and API levels available for use and the percentage of Android devices in the marketplace on which the application will run if that SDK is used as the minimum level.
In general it should only be necessary to select a more recent SDK when that release contains a specific feature that is required for your application. To help in the decision process, selecting an API level from the chart will display the features that are supported at that level. Since the project is not intended for Google TV, Google Glass or wearable devices, leave the remaining options disabled before clicking Next. 3 Creating an Activity The next step is to define the type of initial activity that is to be created for the application.
A range of different activity types is available when developing Android applications. The Master/Detail Flow option will be covered in a later chapter. For the purposes of this example, however, simply select the option to create a Blank Activity. With the Blank Activity option selected, click Next. On the final screen name the activity and title AndroidSampleActivity. The activity will consist of a single user interface screen layout which, for the purposes of this example, should be named activity_android_sample Finally, click on Finish to initiate the project creation process.
4. Modifying the Example Application At this point, Android Studio has created a minimal example application project and opened the main window The newly created project and references to associated files are listed in the Project tool window located on the left hand side of the main project window. The Project tool window has a number of modes in which information can be displayed. By default, this panel will be in Android mode. This setting is controlled by the drop down menu at the top of the panel . If the panel is not currently in Android mode, click on this menu and switch to Android mode The example project created for us when we selected the option to create an activity consists of a user interface containing a label that will read “Hello World” when the application is executed.
The next step in this tutorial is to modify the user interface of our application so that it displays a larger text view object with a different message to the one provided for us by Android Studio. The user interface design for our activity is stored in a file named activity_android_sample.xml which, in turn, is located under app -> res -> layout in the project file hierarchy. Using the Project tool window, locate this file Once located, double click on the file to load it into the User Interface Designer tool which will appear in the center panel of the Android Studio main window Previewing the Layout So far in this chapter, the layout has only been previewed on a representation of the Nexus 4 device. As previously discussed, the layout can be tested for other devices by making selections from the device menu in the toolbar across the top edge of the Designer panel. Another useful option provided by this menu is Preview All Screen Sizes which, when selected, shows the layout in all currently configured device configurations as demonstrated
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