question: public void addRoot ( String name , File root ) { if ( TextUtils . isEmpty ( name ) ) { throw new IllegalArgumentException ( "Name must not be empty" ) ; } try { root = root . getCanonicalFile ( ) ; } catch ( IOException e ) { throw new IllegalArgumentException ( "Failed to resolve canonical path for " + root , e ) ; } mRoots . put ( name , root ) ; }
target:  Add a mapping from a name to a filesystem root. The provider only offers access to files that live under configured roots.