자바 관련 질문 인데, jar파일을 이용한 패키지명 과 메서드명을 알고 싶은데요

java -classpath . PackageUtils /jar_file_path

class 이름
   method 이름1
   method 이름2

import java.util.jar.*;
import java.util.*;
import java.io.*;
import java.net.*;
import java.lang.reflect.*;
 
public class PackageUtils {
 
    public static List<String> getResourceNames(String jarName){
        ArrayList names = new ArrayList ();
 
        try{
            JarInputStream jarFile = new JarInputStream(new FileInputStream (jarName));
 
            JarEntry jarEntry; 
            while(null != (jarEntry = jarFile.getNextJarEntry()) ) {
              names.add(jarEntry.getName());
            }
        }
        catch( Exception e){
            e.printStackTrace ();
        }
        return names;
    }
 
    public static void main (String[] args) throws Exception {
        File f = new File(args[0]);
        List<String> list =  PackageUtils.getResourceNames(f.getAbsolutePath());
        List<String> names = new ArrayList<String>();
 
        for(String s : list) {
            if (s.endsWith(".class")){
                String n = s.replaceAll("/",".").replaceAll(".class$","");
                names.add(n);
            }
        }
 
        URL jarfile = new URL("jar","","file:" + f.getAbsolutePath() +"!/");
        URLClassLoader cl = URLClassLoader.newInstance(new URL[] {jarfile });
 
        for(String n : names){
            try{
                Class c = cl.loadClass(n);
                System.out.println(c.getName());
                for(Method m : c.getMethods()){
                    System.out.println("    " + m.getName());
                }
            } catch(Exception e){
                System.out.println("fail load : "+ n);
                e.printStackTrace();
            }
        }
    }
}