Creating a custom class that utilizes an array

Question

I have created a class, and the object of it is to compare account numbers to an array of account numbers and call a method to return whether a number is valid. I am receiving a compiler error of : Exception in thread "main" java.lang.NullPointerException at program07.AccountVal.(AccountVal.java:12) at program07.Program07.main(Program07.java:18)

Here is my class

package program07;


public class AccountVal
{
    private String[] accountNums;
    private String newAccount;

    public AccountVal()
    {
        accountNums[0] = "5658845";
        accountNums[1] = "8080152";
        accountNums[2] = "1005231";
        accountNums[3] = "4520125";
        accountNums[4] = "4562555";
        accountNums[5] = "6545231";
        accountNums[6] = "7895122";
        accountNums[7] = "5552012";
        accountNums[8] = "3852085";             
        accountNums[9] = "8777541";
        accountNums[10] = "5050552";
        accountNums[11] = "7576651";
        accountNums[12] = "8451277";
        accountNums[13] = "7825877";
        accountNums[14] = "7881200";
        accountNums[15] = "1302850";
        accountNums[16] = "1250255";
        accountNums[17] = "4581002";
        newAccount = "";
    }

    public void setAccountNums(String[] acc)
    {
        accountNums = acc;
    }

    public void setNewAccount(String newAcc)
    {
        newAccount = newAcc;
    }

    public String[] getAccountNums()
    {
        return accountNums;
    }

    public String getNewAccount()
    {
        return newAccount;
    }

    public boolean AccountValidation(String newAccount)
    {
        boolean test = false;

        for (int i = 0; i < 18; i++)
        {
            if(newAccount == accountNums[i])
            {
                test = true;
            }
        }
        return test;
    }
}

The line the error refers to from the program is when i declare the object:

AccountVal test = new AccountVal();

any help would be greatly appreciated. Thank You!

Reimeus · Accepted Answer · 2013-03-04 03:50:53Z

2

The NPE is occurring on this line

accountNums[0] = "5658845";

as the String array accountNums has not been initialized. You could do:

private String[] accountNums = new String[18];

Alternatively, rather than using an array size & using indices, you could declare your array:

private String[] accountNums = { "5658845", "8080152", ... };

edited Mar 4, 2013 at 3:50

answered Mar 4, 2013 at 2:52

Reimeus

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Jon Newmuis · Accepted Answer · 2013-03-04 02:52:38Z

0

You never initialize the accountNums array. You will need to say:

private String[] accountNums = new String[18];

answered Mar 4, 2013 at 2:52

Jon Newmuis

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