java search file in folder

import java.io.File;

public class Main {
   public static void main(String[] argv) throws Exception {
      File dir = new File("directoryName");
      String[] children = dir.list();
      
      if (children == null) {
         System.out.println("does not exist or 
         is not a directory");
      } else {
         for (int i = 0; i < children.length; i++) {
            String filename = children[i];
            System.out.println(filename);
         }
      }
   }
}