code: import java.io.File;
  public class FileRenameTest {
     public static boolean renameFile(String oldname, String newname) {
         // File (or directory) with old name
         File file = new File(oldname);
  
         // File (or directory) with new name
         File file2 = new File(newname);
  
         // Rename file (or directory)
         boolean success = file.renameTo(file2);
         return success;
     }
     public static void test(String type, String oldname, String newname) {
         System.out.println("The following " + type + " called " + oldname +
             ( renameFile(oldname, newname) ? " was renamed as " : " could not be renamed into ")
             + newname + "."
         );
     }
     public static void main(String args[]) {
          test("file", "input.txt", "output.txt");
          test("file", File.separator + "input.txt", File.separator + "output.txt");
          test("directory", "docs", "mydocs");
          test("directory", File.separator + "docs" + File.separator, File.separator + "mydocs" + File.separator);
     }
  }
  