M Developer Preview 2: near-final APIs

Preview 2 arrived on 9 July 2015, within the “late June/early July” window Google had set. Google described it as “near-final APIs” with fixes from developer feedback. Most of its changes were to the permission model.

How Preview 2 reshaped permissions

• Storage. WRITE_EXTERNAL_STORAGE became “dangerous”, so apps must ask for it at runtime. It and READ_EXTERNAL_STORAGE form the STORAGE group.
• Fingerprint. USE_FINGERPRINT became “normal” and no longer needs the user’s approval. It does not give access to fingerprint enrolment.
• Wi-Fi and Bluetooth. BLUETOOTH, BLUETOOTH_ADMIN, CHANGE_WIFI_STATE, CHANGE_WIMAX_STATE and CHANGE_WIFI_MULTICAST_STATE became “normal”. Reading the MAC address of a remote Bluetooth or Wi-Fi device now needs ACCESS_COARSE_LOCATION or ACCESS_FINE_LOCATION.
• Accounts. Some account and identity permissions moved into the CONTACTS group; USE_CREDENTIALS, MANAGE_ACCOUNTS and AUTHENTICATE_ACCOUNTS were left ungrouped “pending further changes”. Bookmark and subscribed-feed permissions were removed.
• System apps. Apps in the system image stopped getting dangerous permissions automatically.
• Rationale. Activity.shouldShowRequestPermissionRationale(String) tells an app whether the user has already refused a permission, so it can explain why it needs it.

Other Preview 2 changes

• USB connections default to charge-only; the user must allow data access.
• android.app.AssistContent and AssistStructure moved to the new android.app.assist package.
• The stylus listeners were renamed: View.OnContextClickListener and GestureDetector.OnContextClickListener replace the OnStylusButtonPress versions.
• InputDevice.hasMicrophone() reports whether an input device has a microphone.

The “Dark” system theme from Preview 1 was gone. 9to5Google later quoted a Googler on the preview issue tracker: “This will not be included in the M release.”