code: public boolean setWritable(boolean writable, boolean ownerOnly) {
          return doChmod(ownerOnly ? S_IWUSR : (S_IWUSR | S_IWGRP | S_IWOTH), writable);
      }
docs: Manipulates the write permissions for the abstract path designated by this
  file.
  
  @param writable
  To allow write permission if true, otherwise disallow
  @param ownerOnly
  To manipulate write permission only for owner if true,
  otherwise for everyone. The manipulation will apply to
  everyone regardless of this value if the underlying system
  does not distinguish owner and other users.
  @return true if and only if the operation succeeded. If the user does not
  have permission to change the access permissions of this abstract
  pathname the operation will fail.
  @since 1.6