Gan, ane ud bertapa siang malam tapi ane masih ada error ini gan
java.lang.NullPointerException.. kayakny ane ada salah ngedeclare ny.. agan" ada yg bisa bantu ga

import java.util.Scanner;

import java.util.StringTokenizer;



public class Nim {

 private player[] p_list; 

 

 public static void main(String[] args)

 {

 Scanner keyboard = new Scanner(System.in);

 

 int counter = 0; //total #of players

 player[] p_list = new player[20];

 System.out.println("Welcome to Nim");

 System.out.println();

 

 while(true)

 {

 

 String str = keyboard.nextLine();

 StringTokenizer tk = new StringTokenizer(str);

 String command;

 command = tk.nextToken();

 if(command.equals("exit"))

 {

 System.out.println("");

 System.exit(0);

 }

 

 if(command.equals("addplayer"))

 {

 String username = "0";

 String family_name = "0";

 String given_name = "0";

 while(tk.hasMoreTokens())

 {

 username = tk.nextToken(" ,");

 family_name = tk.nextToken(",");

 given_name = tk.nextToken(",");

 }

 for(int i = 0; i<= counter; i++)//to check if username already exist

 {

 if(p_list[i].getUsername().equals(username))

 {

 System.out.println("The player already exists.");

 continue;

 }

 else

 {

 p_list[counter].setName(username, given_name, family_name);

 counter++;

 }

 }

 }

}

}

}

public class player {

 private String username;

 private String given_name;

 private String familyname;

 private int gamesPlayed;

 private int win;

 

 //Constructors

 public player(String uname, String gname, String fam_name) {

 setName(uname, gname, fam_name);

 gamesPlayed = 0;

 win = 0;

 }





 //Accessors

 public String getUsername()

 {

 return username;

 }

 public String getgiven_name()

 {

 return given_name;

 }

 public String getfamilyname()

 {

 return familyname;

 }

 private int getGamesPlayed()

 {

 return gamesPlayed;

 }

 private int getWin(){

 return win;

 }

 //Mutators

 public void setName(String uname, String gname, String fam_name)

 {

 username = uname;

 given_name = gname;

 familyname = fam_name;

 }

 public void setGamesPlayed(int n)

 {

 gamesPlayed = n;

 }

 public void setWin(int n)

 {

 win = n;

 }

}

pliss tolongin ane gan, ane ud coba ganti" yg menurut ane salah tp tetep ga bisa beresin