bank

Class TransactionList

java.lang.Object

bank.TransactionList

Direct Known Subclasses:

TransactionListCons, TransactionListNIL

public abstract class TransactionList
extends java.lang.Object

Simple implementation of a list datatype for transactions. All TransactionList subclasses are immutable, i.e. the objects cannot be altered after creation. There are two subclasses, which correspond to the two common constructors NIL (singleton) and CONS of lists.

Field Summary

Fields

Modifier and Type	Field and Description
static TransactionList	EMPTY_LIST

Constructor Summary

Constructors

Constructor and Description
TransactionList()

Method Summary

Methods

Modifier and Type	Method and Description
abstract Transaction	head()
abstract boolean	isEmpty()
abstract int	length()
TransactionList	prepend(Transaction trans) Construct a list whose first element is trans, and whose tail is this list
abstract TransactionList	tail()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

EMPTY_LIST

public static final TransactionList EMPTY_LIST

Constructor Detail

TransactionList

public TransactionList()

Method Detail

head

public abstract Transaction head()

Returns:

the first element of this list, or null iff this list is empty

tail

public abstract TransactionList tail()

Returns:

the tail (the list without its first element) of this list, or null iff this list is empty

isEmpty

public abstract boolean isEmpty()

Returns:

true iff this list is empty

length

public abstract int length()

Returns:

the length of this list

prepend

public TransactionList prepend(Transaction trans)

Construct a list whose first element is trans, and whose tail is this list

Parameters:

trans - the first element of the new list

Returns:

the constructed list