ArrayList prob

Question

Hi,
Im trying to create a program which deals with stats for a football team. I have a class Player containing games played and goals scored which externds from a Class Person which contains details such as Name, DoB ,height etc.
I am trying to store my players in an Arraylist so i can use Comparable to change the order of the list e,g( by name, by games played, by goals scored.)
However, using the BlueJ environment i get i get a compiler error : Using unsafe or unchecked operations on the ArrayList.add line, and a Null exception when running the following code:
import java.util.*;
public class Club
    private String clubName;
    private String name;
    private String surname;
    private int ageInYears;
    private int heightInCm;
    private int weightInKg;
    private int goals;
    private int games;
    private ArrayList playerList;
    public Club(String clubName)   
     this.clubName= clubName;
     ArrayList<Player> playerList =  new ArrayList<Player>();
    public void addPlayer(String name,String surname,int ageInYears,int heightInCm,int weightInKg,int goals, int games)
        this.name= name;
        this.surname= surname;
        this.ageInYears= ageInYears;
        this.heightInCm= heightInCm;
        this.weightInKg= weightInKg;
        this.goals= goals;
        this.games= games;
        playerList.add(new Player(name,surname,ageInYears,heightInCm,weightInKg,goals,games));
        int z= playerList.size();
        System.out.println(z);
}Many thanks for any help or suggestions

Answer 1

but I still get a null pointer exception at the line
playerList.add(new Player(name,surname,ageInYears,heightInCm,weightInKg,goals,games));The only scenario I can think of for a NullPointerException to be thrown by this statement is that playerList is null...
(And I can't understand how something could actually be added in the list in this case...)
Are you sure the exception is thrown at this line? Maybe you could post updated code, and the stack trace.
On another note, I have a class Goalkeeper which extends from Player ( which has extended from person).
Will I be able to add a Goalkeeper into the List even though it expects an Player object?You can add any instance of Player or subclass of Player, so it won't be a problem to add goalkeepers. (Did you try?)
(a Goalkeeper is a Player)