SecurityException in Android when calling reflected method

Question

I´m developing a Cache-Cleaner application, and when I invoke a hidden method in PackageManager I get a SecurityException, though I have given my app the uses-permission "DELETE_CACHE_FILES"

The Uses-Permissions:

uses-permission android:name="android.permission.DELETE_CACHE_FILES"
uses-permission android:name="android.permission.CLEAR_APP_CACHE"
uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"
uses-permission android:name="android.permission.CLEAR_APP_USER_DATA"
uses-permission android:name="android.permission.GET_PACKAGE_SIZE"

The reflected method:

Method method = getPackageManager().getClass().getMethod("deleteApplicationCacheFiles", String.class, IPackageDataObserver.class);

The Error:

java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:507)
at <MY_PACKAGE_NAME>.MainActivity$1.onClick(MainActivity.java:70)
at android.view.View.performClick(View.java:2485)
at android.view.View$PerformClick.run(View.java:9080)
at android.os.Handler.handleCallback(Handler.java:587)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:123)
at android.app.ActivityThread.main(ActivityThread.java:3683)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:507)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.SecurityException: Neither user 10037 nor current process has   android.permission.DELETE_CACHE_FILES.
at android.os.Parcel.readException(Parcel.java:1322)
at android.os.Parcel.readException(Parcel.java:1276)
at android.content.pm.IPackageManager$Stub$Proxy.deleteApplicationCacheFiles(IPackageManager.java:2346)
at android.app.ContextImpl$ApplicationPackageManager.deleteApplicationCacheFiles(ContextImpl.java:2562)
... 14 more

Line 70:

 method.invoke(getPackageManager(), app.packageName, dataObserver);

It says that I don´t have the permission, but I have decleared it in my manifest...

EDIT: I found out this;

W/PackageManager(62): Not granting permission android.permission.DELETE_CACHE_FILES to package <MY_PACKAGE_NAME>.cachecleaner (protectionLevel=3 flags=0x8be46)

EDIT2: Declaration of deleteApplicationCacheFiles(got it via method.toGenericString()):

public void android.app.ContextImpl$ApplicationPackageManager.deleteApplicationCacheFiles(java.lang.String, android.content.pm.IPackageDataObserver)

Answer 1

DELETE_CACHE_FILES is a signature|system permission, meaning that it can only be held by apps that are signed with the firmware's signing key or are installed on the system partition (e.g., by a rooted device user). Ordinary SDK applications cannot hold this permission.

Answer 2

try to use this i tried this code and it worked for me...

private static final long CACHE_APP = Long.MAX_VALUE;
private CachePackageDataObserver mClearCacheObserver; 
void clearCache() {
    if (mClearCacheObserver == null) {
        mClearCacheObserver = new CachePackageDataObserver();
    }

    PackageManager mPM = getPackageManager();

    @SuppressWarnings("rawtypes")
    final Class[] classes = { Long.TYPE, IPackageDataObserver.class };

    Long localLong = Long.valueOf(CACHE_APP);

    try {
        Method localMethod = mPM.getClass().getMethod(
                "freeStorageAndNotify", classes);

        /*
         * Method localMethod=mPM.getClass()
         * .getDeclaredMethod("deleteApplicationCacheFiles", String.class,
         * IPackageDataObserver.class );
         */
        /*
         * Start of inner try-catch block
         */
        try {
            localMethod.invoke(mPM, localLong, mClearCacheObserver);
            // localMethod.invoke(mPM, packageName, mClearCacheObserver);
        } catch (IllegalArgumentException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        /*
         * End of inner try-catch block
         */
    } catch (NoSuchMethodException e1) {
        // TODO Auto-generated catch block
        e1.printStackTrace();
    }
}

private class CachePackageDataObserver extends IPackageDataObserver.Stub {
    public void onRemoveCompleted(String packageName, boolean succeeded) {
        runOnUiThread(new Runnable() {
            public void run() {

                Toast.makeText(MainActivity.this, "cache memory cleared",
                        5000).show();
            }
        });

        Log.d("cachedel", "cache deleted");
    }// End of onRemoveCompleted() method
}