List with NullPointerException

Question

I have a problem with this part of the code. It seems that if I try to add something to a list of Client I get a NullPointerException. I really don't know why because if I debug this part of the code the variable of type Client has information. If someone can help me I would be grateful. Here is the part of the code where the exception appears:

public class Customers {
    private ArrayList<Client> listaClienti;
    public Customers()
    {
    }
    public void addClient(Client c,int i)
    {
        listaClienti.add(i, c);
    }
    public void deleteClient(Client c)
    {
        listaClienti.remove(c);
    }
    public Client getClient(int id)
    {
        return listaClienti.get(id);
    }
}

Idos · Accepted Answer · 2016-03-20T08:25:22.063

4

You are not instantiating your list:

private ArrayList<Client> listaClienti = new ArrayList<>();

You may also instantiate inside your class constructor if you wish:

public Customers() {
    listaClienti = new ArrayList<>();
}

edited Mar 20 '16 at 08:25

answered Mar 20 '16 at 08:13

Idos

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score 0 · Answer 2 · answered Mar 20 '16 at 08:18

0

You got a NullPointerException because you didn't initialize your list

private List<Client> listaClienti = new ArrayList<>();

answered Mar 20 '16 at 08:18

karim mohsen

2,164
1
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19

score 0 · Answer 3 · answered Mar 20 '16 at 08:19

0

first you have to insatantiate your array

ArrayList<Client> listaClienti = new ArrayList<>();

answered Mar 20 '16 at 08:19

Parsania Hardik

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score 0 · Answer 4 · answered Mar 20 '16 at 08:23

0

or

 public Customers()
  {
    listaClienti = new ArrayList<Client>();
 }

answered Mar 20 '16 at 08:23

wayne

1
1

List with NullPointerException

4 Answers4