74. Making Runtime Permission Requests in Android

In a number of the example projects created in preceding chapters, changes have been made to the AndroidManifest.xml file to request permission for the app to perform a specific task. In a couple of instances, for example, internet access permission has been requested in order to allow the app to download and display web pages. In each case up until this point, the addition of the request to the manifest was all that is required in order for the app to obtain permission from the user to perform the designated task.

There are, however, a number of permissions for which additional steps are required in order for the app to function when running on Android 6.0 or later. The first of these so-called “dangerous” permissions will be encountered in the next chapter. Before reaching that point, however, this chapter will outline the steps involved in requesting such permissions when running on the latest generations of Android...

74.1 Understanding Normal and Dangerous Permissions

Android enforces security by requiring the user to grant permission for an app to perform certain tasks. Prior to the introduction of Android 6, permission was always sought at the point that the app was installed on the device. Figure 74-1, for example, shows a typical screen seeking a variety of permissions during the installation of an app via Google Play.

Figure 74-1

For many types of permissions this scenario still applies for apps on Android 6.0 or later. These permissions are referred to as normal permissions and are still required to be accepted by the user at the point of installation. A second type of permission, referred to as dangerous permissions must also be declared within the manifest file in the same way as a normal permission, but must also be requested from the user when the application is first launched. When such a request is made, it appears in the form of a dialog box as illustrated in Figure 74-2...

74.2 Creating the Permissions Example Project

Select the Create New Project quick start option from the welcome screen and, within the resulting new project dialog, choose the Empty Activity template before clicking on the Next button.

Enter PermissionDemo into the Name field and specify com.ebookfrenzy.permissiondemo as the package name. Before clicking on the Finish button, change the Minimum API level setting to API 26: Android 8.0 (Oreo) and the Language menu to Java.

74.3 Checking for a Permission

The Android Support Library contains a number of methods that can be used to seek and manage dangerous permissions within the code of an Android app. These API calls can be made safely regardless of the version of Android on which the app is running, but will only perform meaningful tasks when executed on Android 6.0 or later.

Before an app attempts to make use of a feature that requires approval of a dangerous permission, and regardless of whether or not permission was previously granted, the code must check that the permission has been granted. This can be achieved via a call to the checkSelfPermission() method of the ContextCompat class, passing through as arguments a reference to the current activity and the permission being requested. The method will check whether the permission has been previously granted and return an integer value matching PackageManager.PERMISSION_GRANTED or PackageManager.PERMISSION_DENIED.

Within the MainActivity.java...

74.4 Requesting Permission at Runtime

A permission request is made via a call to the requestPermissions() method of the ActivityCompat class. When this method is called, the permission request is handled asynchronously and a method named onRequestPermissionsResult() is called when the task is completed.

The requestPermissions() method takes as arguments a reference to the current activity, together with the identifier of the permission being requested and a request code. The request code can be any integer value and will be used to identify which request has triggered the call to the onRequestPermissionsResult() method. Modify the MainActivity.java file to declare a request code and request recording permission in the event that the permission check failed:

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import androidx.core.app.ActivityCompat;

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public class MainActivity extends AppCompatActivity {

 

    private static final String TAG = "PermissionDemo";

&...

74.5 Providing a Rationale for the Permission Request

As is evident from Figure 74-3, the user has the option to deny the requested permission. In this case, the app will continue to request the permission each time that it is launched by the user unless the user selected the “Never ask again” option prior to clicking on the Deny button. Repeated denials by the user may indicate that the user doesn’t understand why the permission is required by the app. The user might, therefore, be more likely to grant permission if the reason for the requirements is explained when the request is made. Unfortunately, it is not possible to change the content of the request dialog to include such an explanation.

An explanation is best included in a separate dialog which can be displayed before the request dialog is presented to the user. This raises the question as to when to display this explanation dialog. The Android documentation recommends that an explanation dialog only...

74.6 Testing the Permissions App

On the Android 6 or later device or emulator session on which testing is being performed, launch the Settings app, select the Apps & notifications option and scroll to and select the PermissionDemo app. On the app settings screen, tap the uninstall button to remove the app from the device.

Run the app once again and, when the permission request dialog appears, click on the Deny button. Stop and restart the app and verify that the rationale dialog appears. Tap the OK button and, when the permission request dialog appears, tap the Allow button.

Return to the Settings app, select the Apps option and select the PermissionDemo app once again from the list. Once the settings for the app are listed, verify that the Permissions section lists the Microphone permission:

Figure 74-4

74.7 Summary

Prior to the introduction of Android 6.0 the only step necessary for an app to request permission to access certain functionality was to add an appropriate line to the application’s manifest file. The user would then be prompted to approve the permission at the point that the app was installed. This is still the case for most permissions, with the exception of a set of permissions that are considered dangerous. Permissions that are considered dangerous usually have the potential to allow an app to violate the user’s privacy such as allowing access to the microphone, contacts list or external storage.

As outlined in this chapter, apps based on Android 6 or later must now request dangerous permission approval from the user when the app launches in addition to including the permission request in the manifest file.