Runtime permission dialog is shown in Android 6.0 or higher, so Activity.requestPermissions(...) which was added in API level 23 makes sense.
But why is there another one (ActivityCompat.requestPermissions(...)) to be used for below Android 6.0? Does this show runtime permission request dialog in lower versions?
What is the difference between
Activity.requestPermissions(permissions, requestCode)
and
ActivityCompat.requestPermissions(activity, permissions, requestCode)
Which one should I use?
Does this show runtime permission request dialog in lower versions?
No. There is no such dialog on lower versions. It will simply call your onRequestPermissionsResult() method to let you know that you hold the permissions (since, by definition, you already do).
What is the difference between
Activity#requestPermissions() is for apps with a minSdkVersion of 23 or higher, or for apps whose developers like calling if (Build.VERSION.SDK_INT >= 23) to avoid that call on older devices.
ActivityCompat.requestPermissions() is for any app, as it "does the right thing" on all supported API levels (back to API Level 14 IIRC).
Which one should I use?
If your minSdkVersion is 23 or higher, feel free to use Activity#requestPermissions(). Otherwise, I recommend ActivityCompat.requestPermissions().
But why is there another one (ActivityCompat.requestPermissions(...)) to be used for below Android 6.0?
It exists because there are two types of Acvivity in Android, android.app.Activity docs, and android.support.v4.app.ActivityCompatdocs.
Activity is for use in devices whose min SDK version is 14 iircActivityCompat is for backwards compatibility (SDK 9 and above). It allows you to have access to supportable new features and Material themes without any of the breaking changes that the new OS versions introduced to achieve the new features and UI.
Does this show runtime permission request dialog in lower versions?
No. Android 6.0 is the first to show runtime Permission dialogs and as such previous versions of Android cannot show them. That bit of code is actually ignored by previous versions of the OS iirc.
Which one should I use?
That wholly depends on which type of Activity you are using. If your activity is a child of Activity then use Activity.requestPermissions(permissions, requestCode). if you are using a child of ActivityCompat however, use ActivityCompat.requestPermissions(activity, permissions, requestCode).
