main() Can't See Private Data

The main() method changes the CheckingAccount object by using the object's access methods. Here is a different main() that does not use the access methods.

class CheckingAccount
{
  private String accountNumber;
  private String accountHolder;
  private int    balance;
  . . . .
}

class CheckingAccountTester
{
  public static void main( String[] args )
  {
    CheckingAccount bobsAccount = new CheckingAccount( "999", "Bob", 100 );

    System.out.println( bobsAccount.balance );
    bobsAccount.balance = bobsAccount.balance + 200;
    System.out.println( bobsAccount.balance );
 
  }
}