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);
}

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 ) ; }
add a mapping from a name to a filesystem root . the provider only offers access to files that live under configured roots .
