Using Permissions


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A basic Android application has no permissions associated with it, meaning it can not do anything that would adversely impact the user experience or any data on the device. To make use of protected features of the device, you must include in your

AndroidManifest.xml one or more <uses-permission> tags declaring the permissions that your application needs.

At application install time, permissions requested by the application are granted to it by the package installer, based on checks against the signatures of the applications declaring those permissions and/or interaction with the user. No checks with the user are done while an application is running: it either was granted a particular permission when installed, and can use that feature as desired, or the permission was not granted and any attempt to use the feature will fail without prompting the user.

Often times a permission failure will result in a SecurityException being thrown back to the application. However, this is not guaranteed to occur everywhere. For example, the sendBroadcastflntenf) method checks permissions as data is being delivered to each receiver, after the method call has returned, so you will not receive an exception if there are permission failures. In almost all cases, however, a permission failure will be printed to the system log.

The permissions provided by the Android system can be found at Manifest.permission. Any application may also define and enforce its own permissions, so this is not a comprehensive list of all possible permissions.

A particular permission may be enforced at a number of places during your program's operation:

• At the time of a call into the system, to prevent an application from executing certain functions.

• When starting an activity, to prevent applications from launching activities of other applications.

• Both sending and receiving broadcasts, to control who can receive your broadcast or who can send a broadcast to you.

• When accessing and operating on a content provider.

• Binding or starting a service.

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