[SOLVED] CS1331 Homework 6

Description

Introduction

In this assignment you will practice

• Using Optional
• Using Predicate
• Using Lists
• Using Lambdas, Anonymous classes, and Inner classes

Problem Description

In this homework, you will create many useful classes for our end goal of making an ATM database!

• Transaction
  • Keeps track of withdrawals/deposits from/into an account.
• Account
  • Keeps track of a list of Transactions for a customer.

You will be provided a TransactionType enum.

Solution Description

Classes:

• Transaction

• • fields:
    • TransactionType type;
    • double amount;
    • Optional<String> comment; (See link above for Optional documentation)
  • methods:
    • Getter methods for all fields.
    • boolean hasComment() should return true if comment is not empty, false otherwise.
  • constructors:
    • one that takes in type and amount in that order and assigns them. Sets the comment to Optional.empty().
    • one that takes in type and amount in that order and assigns them. Also take in a third parameter that is a String that represents that value of the comment. Properly initialize the comment field with this String.

• Account

• • fields:
    • List<Transaction> pastTransactions
  • methods:
    • Transaction getTransaction(int n): returns the nth transaction from pastTransactions. n will always be valid.
    • List<Transaction> findTransactionsByPredicate(Predicate<Transaction> predicate): Returns a list of Transactions from pastTransactions filtered by the predicate. If the predicate returns true when a Transaction is passed in, keep it. Otherwise filter it out of the returned list. Must not modify pastTransactions field. (See link above for documentation on Predicate)
    • List<Transaction> getTransactionsByAmount(double amount): returns a list of Transactions with an amount field that equals the parameter amount. Must not modify pastTransactions field. Must call findTransactionsByPredicate with an instance of an inner class.
    • List<Transaction> getWithdrawals(): returns a list of Transactions that are withdrawals. Must not modify pastTransactions field. Must call findTransactionsByPredicate with an instance created with an anonymous inner class.
    • List<Transaction> getDeposits(): returns a list of Transactions that are deposits. Must not modify pastTransactions field. Must call findTransactionsByPredicate with an instance created with a lambda expression.
    • List<Transaction> getTransactionsWithCommentLongerThan(int length): returns a list of Transactions with comments that are longer than length. Must not modify pastTransactions field. Must call findTransactionsByPredicate but you can use whatever technique to create the Predicate that you like.
    • List<Transaction> getTransactionsWithComment(): returns a list of Transactions with a comment that is not empty. Must not modify pastTransactions field. Must call findTransactionsByPredicate with a lambda expression or method reference. Method references aren’t taught but they are very useful so feel free to look up how to use them!
    • Getter for pastTransactions.
  • constructors
    • Make a constructor that takes in a List of Transactions assign that list to pastTransactions.

If there are any classes that you are unfamiliar with (e.g. Predicate or Optional), look them up in Javadocs. Make the visibility of all the methods and fields as you see best fits good programming style.

Allowed imports

If there is something else you’d like to use, ask on Piazza.

• Optional
• Predicate
• List
• Any subclass of List

Running and Testing

You should create your own testing class to verify that your code works (Don’t submit it though).

Make sure that all your code can be compiled and ran from the command line.

Tips and Considerations

Please start as soon as possible! The earlier you start this assignment, the more time you will have to think and ask questions. If anything seems confusing, read through the entire description and instructions again. As always, feel free to contact your TAs, post on Piazza, or come in for office hours.

Javadocs

• You will need to write Javadoc comments. Not following the Javadoc requirements will count as checkstyle errors.
  • Every class should have a class level Javadoc that includes @author <GT Username>.
  • Every method should have a Javadoc explaining what the method does and includes any of the following tags if applicable.
    • @param <parameter name> <brief description of parameter>
    • @returns <brief description of what is returned>
    • @throws <Exception> <brief explanation of when the given exception is thrown>
  • See the CS 1331 Style Guide section on Javadoc comments for examples.