Java, Null Pointer Exception. when I add an object to an array

Question

I am new to java, I am trying to add an object to an array of objects. I have 2 Class, Bank and Account. Bank contains an array of Accounts objects.

Bank constructor initializes the Accounts array.

public Bank (String bankName, int num) {

        nameOfBank = bankName;
        max = num;
        Account[] accounts = new Account[max];
        count = 0;

This is my addAccount method.

public boolean addAccount (Account acct) {
        if(acct == null) {
            return false;
        }

        accounts[count++] = acct;
        return true;
    }

This is how I add the account in main

newBank.addAccount(test);

ps. I am not allowed to use anything other than java array.(no arrayList)

Exception in thread "main" java.lang.NullPointerException
        at Bank.addAccount(Bank.java:55)
        at TestBank.main(TestBank.java:15)

Answer 1

You've defined accounts as a local variable to the constructor, not a class level member.

public class Bank {
    Account[] accounts;
    int count;

    public Bank(String bankName, int num) {
        accounts = new Account[num];
        count = 0;
    }

    public boolean addAccount(Account acct) {
        // Do your work
    }
}