import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.Path;

Configuration conf = new Configuration();
FileSystem fs = FileSystem.get(conf);
Path nomcomplet = new Path("/user/etudiant1", "bonjour.txt");
FileStatus infos = fs.getFileStatus(nomcomplet);
System.out.println(Long.toString(infos.getLen())+" octets");
fs.rename(nomcomplet, new Path("/user/etudiant1","salut.txt"));