If you start a service that runs from an activity and the user navigates away from the activity to another app, the service will continue to run. Services are different from the activity components that we've looked at previously, in a number of important ways. You can create a service class in Eclipse using the same process you would for an activity, choosing service as the superclass. To add a service component to the manifest, use the following syntax with the element placed inside the application element: This takes the background processing away from the UI, but your activity can receive the results of the AsyncTask operation to update the UI. Depending on the needs of your application, it may be more appropriate to use an inner AsyncTask class inside your activity. Tip: If you want to carry out background processing such as fetching Internet data, you do not necessarily need to implement a service class. The user can continue to interact with the activity while the service runs because it executes in the background. A typical example is an app in which an activity starts a service running on user interaction, with the service perhaps uploading data to a web resource. A service doesn't have a user interface, so they are often combined with other components such as activities. Services are typically used for processes that are ongoing or that take a significant period of time. I'll also mention a couple of resources your apps are most likely to use, including fragments and the action bar.Ī service in Android is a background process.
We've met Activities already so I won't spend any more time on them, but I will go through the other three main app components. Whenever you create or use any of them, you must include elements in the project manifest. There are four main Android app components: activities, services, content providers, and broadcast receivers. But before you do, we will run through some common Android components in this tutorial, then have a quick look at the SDK samples in the next tutorial. You can use what we covered already to start creating your own apps. So far, we've looked at the structure and typical elements in an Android app, including user interface elements and data storage. In this series we are learning the essential features of Android development that you need to know to start building apps.
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