Delete system cache on android 6.0

Question

I'm using method freeStorageAndNotify() with permission android.permission.CLEAR_APP_CACHE to delete system cache of all installed applications. But the method started throwing InvocationTargetException from the android marshmallow 6.0 version. After googling the issues I found the same issue as reported here: Android M reflection method freeStorageAndNotify exception So here the conclusion was, freeStorageAndNotify() stopped working since google has raised the method's signature level now to signature|system.

But now the question is how other third-party apps like 'Clean master' are still able to delete system cache of all installed applications by taking accessibility permission from the user for 6.0 devices?

Have you tried [peeking](http://www.decompileandroid.com/) into the APK? — kichik, Apr 04 '16 at 20:59
Have you tried to delete the cache folder directly? (Probably you need the read/write storage access permission, but i'm not sure you can do it) — Stefano P., Apr 07 '16 at 11:38

score 0 · Answer 1 · answered Jun 18 '17 at 09:32

I don't think that 'Clean master' actually uses Accessibility Permissions to clean installed apps cache. But, if you're interested, this goal can be achieved by using AccessibilityService in your application. Within your class that extends AccessibilityService you have this callback:

    @Override
    public void onAccessibilityEvent(AccessibilityEvent aEvent) {
       AccessibilityNodeInfo rootNode = aEvent.getSource();
       //...
    }

Here you can invoke rootNode.findAccessibilityNodeInfosByViewId() or rootNode.findAccessibilityNodeInfosByText(), it will return all matching AccessibilityNodeInfo objects (sub-nodes) in tree. Then, you just need to detect which of them is Button (node.getClassName()) and call subNode.performAction(AccessibilityNodeInfo.ACTION_CLICK).

On Android M, you first need to to open system's App Info screen (you can find instructions here How can I start android application info screen programmatically?) for the concrete app and, by the scheme described above, perform sequential clicks on the buttons "Storage" —> "Clear cache".

In order to clear cache for all installed apps you probably have to iterate through the all installed apps (List<ApplicationInfo> installedApplications = context.getPackageManager.getInstalledApplications(0);) and repeat the procedure mentioned above.

score -1 · Answer 2 · edited Jul 26 '20 at 08:47

-1

The system cleaner I'm using has access to the STORAGE permissions. This permission gives the app authority to clear any data in the shared external storage directory.

http://developer.android.com/reference/android/Manifest.permission_group.html#STORAGE

I don't think any 3rd party app can actually clear system cache anymore unless the device is rooted and the app is designed for rooted devices.

clean Master permission

clean Master asking for permission

edited Jul 26 '20 at 08:47

answered Mar 31 '16 at 11:46

Aaron Franco

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I know that. My question is how "Clean Master" app can able to do it by taking accessibility permission from user. – Audumbar Apr 01 '16 at 04:55
Clean Master only takes the STORAGE permission. – Aaron Franco Apr 01 '16 at 11:35
Clean Master expressly asks to access the STORAGE PERMISSION – Aaron Franco Apr 01 '16 at 11:36
If you look at the full set of permissions, Clean Master doesn't use Accessibility permissions at all. – Aaron Franco Apr 01 '16 at 12:53
Clean master asks for Accessibility permission from the user, when you need to clear the cache files. – Logo Nov 05 '19 at 05:26

score -4 · Answer 3 · answered Apr 04 '16 at 20:52

those apps only do the same thing all the time. use it on an old device and a new device the results are the same. the only help i have seen is that they can kill or restart some background processes, not to clean the cache. therefore no API can restrict their trick..

Delete system cache on android 6.0

3 Answers3