Logout Open In App
Open In App
Warning: foreach() argument must be of type array|object, bool given in /var/www/html/web/app/themes/studypress-core-theme/template-parts/header/mobile-offcanvas.php on line 20

Chapter 8: Problem 6

\((\text {Savings Account Class})\) Create class SavingsAccount. Use a static variable annual InterestRate to store the annual interest rate for all account holders. Each object of the class contains a private instance variable savingsBal ance indicating the amount the saver currently has on deposit. Provide method calculateMonth1yInterest to calculate the monthly interest by multiplying the savingsBalance by annualInterestRate divided by \(12-\) this interest should be added to savingsBalance. Provide a static method modifyInterestRate that sets the annual InterestRate to a new value. Write a program to test class SavingsAccount. Instantiate two savingsAccount objects, saver1 and saver \(2,\) with balances of \(\$ 2000.00\) and \(\$ 3000.00,\) respectively. Set annual InterestRate to \(4 \%,\) then calculate the monthly interest for each of 12 months and print the new balances for both savers. Next, set the annual InterestRate to \(5 \%\), calculate the next month's interest and print the new balances for both savers.

Short Answer

Expert verified
Instantiate the SavingsAccount class with two savers. Compute monthly interest and update balances for 12 months at 4% annual interest rate. Then change the rate to 5%, compute the next month's interest, and print the updated balances for both savers.

Step by step solution

01

- Declaring the SavingsAccount Class

Define the SavingsAccount class with a private instance variable 'savingsBalance' and a static variable 'annualInterestRate'.
02

- Implementing the calculateMonthlyInterest Method

Implement the 'calculateMonthlyInterest' method to calculate and add the monthly interest to 'savingsBalance'. The monthly interest is calculated by 'savingsBalance * (annualInterestRate / 12)'.
03

- Implementing the modifyInterestRate Static Method

Implement the static method 'modifyInterestRate' to adjust the value of 'annualInterestRate'.
04

- Creating and Testing the SavingsAccount Objects

Instantiate two SavingsAccount objects with the given initial balances. Use the 'modifyInterestRate' method to set the initial annual interest rate and then calculate and display the monthly interest and updated balances for each month.
05

- Changing the Annual Interest Rate

Use the 'modifyInterestRate' method to update the annual interest rate to the new value and compute and display the new balances after applying the new monthly interest rate for each saver.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Start your free trial

Over 30 million students worldwide already upgrade their learning with Vaia!

Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Java programming
Java is a widely-used programming language designed for use in the distributed environment of the internet. It is known for its simplicity, reliability, and cross-platform capabilities. Specifically, Java shines through its implementation of object-oriented programming principles, which allow developers to create modular programs and reusable code.

When it comes to defining a SavingsAccount class in Java, you're applying these object-oriented principles. You start by defining the class and its attributes, which in Java, are typed variables. Functions, known as methods, are also declared within the class to perform actions or operations like calculating the monthly interest. In the case of our savings account example, a static variable is used for a shared annual interest rate, while instance variables represent each unique account's balance. These Java constructs work together to provide a blue print that can be used to instantiate objects with both shared and individual characteristics.
Object-oriented programming
Object-oriented programming (OOP) is a paradigm centered around 'objects' rather than 'actions'. In OOP, instead of writing a sequence of instructions to perform a task, you create objects that encapsulate both data and operations.

OOP uses several key concepts including encapsulation, inheritance, and polymorphism to facilitate reuse and maintenance of code. Encapsulation means that an object's internal state is protected from outside interference by restricting access to certain components, typically through access modifiers like 'private'. In our SavingsAccount example, the user's balance is kept private to protect it from direct manipulation, and methods are provided to interact with this data safely.
Static variables
In Java, static variables belong to the class as opposed to instances of the class (objects). This means there's only one copy of a static variable shared by all instances of the class. With the SavingsAccount class, the static variable 'annualInterestRate' is shared across all SavingsAccount objects.

Using static variables has its uses, particularly for representing properties that should remain consistent across all instances of a class—like our interest rate, which is the same for all accounts at a given time. It's important that when you modify a static variable, such as with the 'modifyInterestRate' method, you understand that the change affects all objects of the class due to this shared nature.
Instance variables
Conversely, instance variables are unique to each instance of a class and represent the state of an object. In our SavingsAccount example, 'savingsBalance' is an instance variable. Each SavingsAccount object has its own 'savingsBalance' that stores an individual balance separate from other account objects.

Instance variables are fundamental in representing the distinct characteristics of an object, which relates back to encapsulation in object-oriented programming. When we calculate the monthly interest, we operate on this 'savingsBalance' instance variable, reinforcing the idea that while some properties are shared (like the annual interest rate), others are specific to the individual object.

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

(Huge Integer Class) Create a class HugeInteger which uses a 40 -element array of digits to store integers as large as 40 digits each. Provide methods parse, toString, add and subtract. Method parse should receive a String, extract each digit using method charAt and place the integer equivalent of each digit into the integer array. For comparing HugeInteger objects, provide the following methods: isEqualTo, isNotEqualTo, isGreaterThan, isLessThan, isGreaterThanOrEqualTo and isLessThanorEqualTo. Each of these is a predicate method that returns true if the relationship holds between the two HugeInteger objects and returns false if the relationship does not hold. Provide a predicate method iszero. If you feel ambitious, also provide methods multiply, divide and remainder. [Note: Primitive boolean values can be output as the word "true" or the word "false" with format specifier \(\% \text { b. }]\)

Complex Numbers) Create a class called Complex for performing arithmetic with complex numbers. Complex numbers have the form \\[ \text {realPart }+\text { imaginaryPart } * i \\] where \(i\) is \\[ \sqrt{-1} \\] Write a program to test your class. Use floating-point variables to represent the private data of the class. Provide a constructor that enables an object of this class to be initialized when it's declared. Provide a no-argument constructor with default values in case no initializers are provided. Provide pub 7 ic methods that perform the following operations: a) Add two Complex numbers: The real parts are added together and the imaginary parts are added together. b) Subtract two Complex numbers: The real part of the right operand is subtracted from the real part of the left operand, and the imaginary part of the right operand is subtracted from the imaginary part of the left operand. c) Print Complex numbers in the form (reallart, imaginaryPart).

Fill in the blanks in each of the following statements:\ a) \(A(n)\) _____ imports all static members of a class. b) String class static method ______ is similar to method System. out.printf, but returns a formatted String rather than displaying a String in a command window. c) If a method contains a local variable with the same name as one of its class's fields, the local variable _____ the field in that method's scope. d) The public methods of a class are also known as the class's _______ Or ______ e) \(A(n)\) ______ declaration specifies one class to import. f) If a class declares constructors, the compiler will not create a(n) _______ g) An object's _____method is called implicitly when an object appears in code where a String is needed. h) Get methods are commonly called _____or ______ i) \(\quad A(n)\) _______ method tests whether a condition is true or false. j) For every enum, the compiler generates a static method called ______ that returns an array of the enum's constants in the order in which they were declared. k) Composition is sometimes referred to as a(n) _______ relationship. I) \(A(n)\) ______ declaration contains a comma-separated list of constants. \(\mathrm{H}(\mathrm{n})\)_______ variable represents classwide information that's shared by all the objects of the class. n) \(A(n)\) ________ declaration imports one static member. o) The ______ states that code should be granted only the amount of privilege and access that it needs to accomplish its designated task. p) Keyword _____ specifies that a variable is not modifiable after initialiation in a declaration or constructor. q) \(A(n)\) ______ declaration imports only the classes that the program uses from a particular package. r) Set methods are commonly called _______ because they typically change a value. s) Use class _______ to perform precise monetary calculations. t) Use the ______ statement to indicate that a problem has occurred.

(Date Class ) Create class Date with the following capabilities: a) Output the date in multiple formats, such as MM/DD/YYYY June 14,1992 DDD YYYY b) Use overloaded constructors to create Date objects initialized with dates of the formats in part (a). In the first case the constructor should receive three integer values. In the second case it should receive a String and two integer values. In the third case it should receive two integer values, the first of which represents the day number in the year. [Hint: To convert the String representation of the month to a numeric value, compare Strings using the equals method. For example, if \(s 1\) and \(s 2\) are Strings, the method call s1.equals(s2) returns true if the Strings are identical and otherwise returns false.

\((\text {Rectangle Class})\) Create a class Rectangle with attributes length and width, each of which defaults to \(1 .\) Provide methods that calculate the rectangle's perimeter and area. It has set and get methods for both length and width. The set methods should verify that Tength and width are each floating- point numbers larger than 0.0 and less than \(20.0 .\) Write a program to test class Rectangle.
See all solutions

Recommended explanations on Computer Science Textbooks

Computer Programming

Read Explanation

Data Structures

Read Explanation

Databases

Read Explanation

Blockchain Technology

Read Explanation

Issues in Computer Science

Read Explanation

Game Design in Computer Science

Read Explanation
View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.

Sign-up for free