import java.math.*;
/** This class represents checking accounts. It implements state
    and behavior that define how a checking account differs from 
    a general bank account. */
public class CheckingAccount extends BankAccount { 
   /** Holds the string identifying the type of all checking accounts. */
   private static final String ACCOUNT_TYPE = "C";
   /** Holds the overdraft amount for this account. This is the amount
       by which a withdrawal or check can exceed the current balance. */
   private BigDecimal overDraftLimit;
   /** Create a new empty checking account. Note that the superclass
       constructor is also executed. */
   CheckingAccount() { }
   /** Return the account type string. */
   public String getAccountType() { return ACCOUNT_TYPE; }
   /** Return the overdraft limit amount. */
   public BigDecimal getOverDraftLimit() {
      if (overDraftLimit == null) 
         setOverDraftLimit(new BigDecimal(0.0));
      return overDraftLimit;
   }
   /** Return the maximum withdrawal amount. Withdrawals may be made up to the
       current balance plus the overdraft limit. */
   public BigDecimal getWithdrawalLimit() {
      return getBalance().add(getOverDraftLimit());
   }   
   /** Set the overdraft limit amount. */
   public void setOverDraftLimit(BigDecimal anAmount) {
      overDraftLimit = anAmount.setScale(2, BigDecimal.ROUND_HALF_DOWN);
   }
}