1.    File path = new File(".");
      String[] list;
      list = path.list();
      

2. File f=new File("aa.txt");  

private static void fileData(File f) {
    System.out.println(
      "Absolute path: " + f.getAbsolutePath() +
      "\n Can read: " + f.canRead() +
      "\n Can write: " + f.canWrite() +
      "\n getName: " + f.getName() +
      "\n getParent: " + f.getParent() +
      "\n getPath: " + f.getPath() +
      "\n length: " + f.length() +
      "\n lastModified: " + f.lastModified());
    if(f.isFile())
      System.out.println("it's a file");
    else if(f.isDirectory())
      System.out.println("it's a directory");
  }