Involving Array Of Objects And Referencing Methods Of Each

I'm working on a project that involves the following:

-Creating a superclass of bankaccounts
-Creating two subclasses, checkingaccount and savingaccount
-Each of the two subclasses has different methods (writeCheck for checking, for example)
-Both types are created in a main class bank and stored in the same array

So let's say a user goes through the menus and creates a few savingAccounts and a few checkingAccounts (stored in the accounts[] array). Then, to write a check from one account, the user can enter the account number (a string), and the method will use a for loop to cycle through the array until it hits an account number match. Then it checks that it's the correct account type and calls methods from the subclass.

Problem here is that some methods work and some don't. In the following example:

for (BankAccount account: accounts) {
if (account.getAccountType().equals("Checking")) {
do {
if (account.getAccountNumber().equals(accountNumber)) {
amount = Double.parseDouble(JOptionPane.showInputDialog(

[Code] .....

The getAccountNumber method works but writeCheck is throwing an error. I tried creating a method in the superclass and overriding it in the subclasses but with no success.