error: <anonymous PacketCounter$1> is not abstract and does not override abstract method nextPacket(JPacket,Object) in JPacketHandler

Question

During running this java code of calculating packets from pcaps file. :

 // Counting the number of packets in pcap files.
  
// User defined package
//package jnt;
  
import java.io.File;
import org.jnetpcap.Pcap;
import org.jnetpcap.packet.JPacket;
import org.jnetpcap.packet.JPacketHandler;
  
public class PacketCounter {
  
    // Path of the folder having pcap files
    // generated by Wireshark(change accordingly)
    static String folderpath
        = "./pcapfiles/";
  
    static double count = 0;
    static double globalcount = 0;
  
    // main function starts here
    public static void main(String[] args)
    {
  
        // Making the object of a file
        // and giving that object address
        // of the pcap folder
        File file = new File(folderpath);
  
        // Making file array which is used
        // to access each file
        // inside the folder one-by-one
        File[] files = file.listFiles();
  
        // Accessing each file
        // one-by-one of files array
        for (File f : files) {
  
            // Getting each pcap file name
            String FILENAME
                = folderpath + f.getName();
  
            // StringBuilder is used to get
            // error messages in case
            // if any error occurs
            StringBuilder errbuf = new StringBuilder();
  
            // Making Pcap object an opening pcap file
            // in offline mode and passing pcap filename
            // and StringBuilder object to the function
            Pcap pcap = Pcap.openOffline(FILENAME, errbuf);
  
            // Here pcap object is used to start a loop
            // for capturing each  packet of an
            // each pcap file(as a pcap file can
            // have many packets) one at a time, here -1
            // indicates eof(end of file) i.e
            // until every packet is captured execute the
            // loop, we can also give some value
            // instead of -1 which will indicate the
            // number of packets to execute
            // in each pcap file
  
            pcap.loop(-1, new JPacketHandler() {
  
                // nextPacket is override function
                // of JPacketHandler( Handler which is
                // use to receive fully decoded packets)
                public void nextPacket(JPacket packet,
                                       StringBuilder errbuf)
                {
  
                    // counter to count the number of packet
                    // in each pcap file
                    count++;
                }
            }, errbuf);
  
            System.out.println("File : " + f.getName()
                               + " Number of Packets : "
                               + count);
  
            // Global counter to count the total number
            // of packets in all pcap file
            globalcount = globalcount + count;
  
            count = 0;
        }
  
        System.out.println("Total Packets in folder : "
                           + globalcount);
    }
}

Get from https://www.geeksforgeeks.org/packet-capturing-using-jnetpcap-in-java/

Error showing in this image, also below.

javac -cp jnetpcap.jar PacketCounter.java
Picked up _JAVA_OPTIONS: -Dawt.useSystemAAFontSettings=on -Dswing.aatext=true
PacketCounter.java:64: error: <anonymous PacketCounter$1> is not abstract and does not override abstract method nextPacket(JPacket,Object) in JPacketHandler
            pcap.loop(-1, new JPacketHandler() {
                                               ^
Note: PacketCounter.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
1 error

Please help me to run this code .

Operating system : Kali linux

Java version : openjdk 11.0.11-ea 2021-04-20 OpenJDK Runtime Environment (build 11.0.11-ea+4-post-Debian-1) OpenJDK 64-Bit Server VM (build 11.0.11-ea+4-post-Debian-1, mixed mode, sharing)