question: public static boolean isSystemApplication ( PackageManager packageManager , String packageName ) { if ( packageManager == null || packageName == null || packageName . length ( ) == 0 ) { return false ; } try { ApplicationInfo app = packageManager . getApplicationInfo ( packageName , 0 ) ; return ( app != null && ( app . flags & ApplicationInfo . FLAG_SYSTEM ) > 0 ) ; } catch ( NameNotFoundException e ) { e . printStackTrace ( ) ; } return false ; }
target:  whether packageName is system application