Clever Geek Handbook

Should I use ContextCompat or PermissionChecker to check Android permissions?

I can select one of the following verification methods to see if my application has this permission.

Which one is preferable?

ContextCompat

(from support-compat

lib):

ContextCompat.checkSelfPermission(context, Manifest.permission.WRITE_EXTERNAL_STORAGE)

Or PermissionChecker

(from support-core-utils

lib):

PermissionChecker.checkSelfPermission(context, Manifest.permission.WRITE_EXTERNAL_STORAGE)

Note that (as of 25.3.1) -core-utils depends on -compat:

| | +--- com.android.support:support-core-utils:25.3.1 | | | +--- com.android.support:support-annotations:25.3.1 | | | \--- com.android.support:support-compat:25.3.1 (*)

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2 answers


In the original state, PermissionChecker

we can see that it calls first Context#checkPermission

and is released earlier if the calling code has no permission. If the calling code has permission, it goes to the mysterious one AppOpsManager

asking if we have permissionToOp

, and then checking for a return noteProxyOp

. This gives us a hint as to what this method is for, since the docs for noteProxyOp

start with:

Notice the application performing the operation on behalf of another application while processing IPC.

Additionally, if we inspect the return value of the method PermissionChecker

, we see that we are returning one of three possible results:

Permission check result, which is either PERMISSION_GRANTED

, or, PERMISSION_DENIED

or PERMISSION_DENIED_APP_OP

.



That is, 0, -1, or -2 will return values. This class appears to be intended for use by applications that receive interprocess communication and perform actions on behalf of other applications.

ContextCompat

, on the other hand, just grabs the current process id and returns the result Context#checkPermission

:

PERMISSION_GRANTED

if the given pid / uid is allowed this permission, or PERMISSION_DENIED

if it is not.

So for most developers writing standard Android apps, useContextCompat

.

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I will go with ContextCompat

because of the documentation and the quality of the tutorials available

But I read something:
If your device is running Android M and above and the targetSdkVersion is below 22, there is a slight difference between the two.
When you launch the app for the first time with the device permission disabled, the behavior looks like this:

  • ContextCompat: always returns GRANTED
  • PermissionChecker: Returns GRANTED or PERMISSION_DENIED_APP_OP


It PermissionChecker

might be wiser with this usage , but again you need to set targetSdkVersion to 23 or higher to implement runtime permissions.

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