Practice Methods

Topics

Exercises on Different Forms of Methods
Exercises on When and Where to use Methods
Next Topic: Static

Implementing Methods: New Exercises to Practice Writing Methods

Exercises on Different Forms of Methods (8 Exercises)

Here are 8 exercises that explore different combinations of parameters and return types in methods.

1. Method with No Parameters and No Return Value

Scenario: Create a class to simulate a basic greeting message.

Class Name: Greeter
Method: public void sayHello()
Task: Write a method sayHello() that prints “Hello, welcome!” to the console. This method does not take any parameters and does not return anything.

Instructions:

Implement the sayHello() method in the Greeter class.
In a GreeterTester class, create an instance of Greeter and call the sayHello() method.

2. Method with No Parameters and a Return Value

Scenario: Create a class to generate a random number.

Class Name: RandomNumberGenerator
Method: public int generateNumber()
Task: Write a method generateNumber() that returns a random number between 1 and 100. This method does not take any parameters but returns an int.

Instructions:

Implement the generateNumber() method in the RandomNumberGenerator class.
In a RandomNumberGeneratorTester class, create an instance of RandomNumberGenerator and print the value returned by generateNumber().

3. Method with Parameters and No Return Value

Scenario: Create a class to calculate the sum of two numbers and display it.

Class Name: Calculator
Method: public void displaySum(int num1, int num2)
Task: Write a method displaySum(int num1, int num2) that takes two integers as parameters and prints their sum. This method takes parameters but does not return anything.

Instructions:

Implement the displaySum(int num1, int num2) method in the Calculator class.
In a CalculatorTester class, create an instance of Calculator and call the displaySum() method with different sets of numbers.

4. Method with Parameters and a Return Value

Scenario: Create a class to calculate the average of three numbers.

Class Name: Statistics
Method: public double calculateAverage(double num1, double num2, double num3)
Task: Write a method calculateAverage(double num1, double num2, double num3) that takes three double values as parameters and returns their average as a double.

Instructions:

Implement the calculateAverage(double num1, double num2, double num3) method in the Statistics class.
In a StatisticsTester class, create an instance of Statistics, call the calculateAverage() method with different sets of numbers, and print the results.

5. Method with Multiple Parameters and a Return Value

Scenario: Create a class to calculate the area of a triangle.

Class Name: Geometry
Method: public double calculateTriangleArea(double base, double height)
Task: Write a method calculateTriangleArea(double base, double height) that takes the base and height of a triangle as parameters and returns the area as a double.

Instructions:

Implement the calculateTriangleArea(double base, double height) method in the Geometry class.
In a GeometryTester class, create an instance of Geometry and test the method with different values of base and height.

6. Method with No Parameters but Multiple Return Values (using an array or object)

Scenario: Create a class to generate basic statistics (min, max, average) from a set of predefined numbers.

Class Name: StatisticsGenerator
Method: public double[] getBasicStatistics()
Task: Write a method getBasicStatistics() that returns an array containing the minimum, maximum, and average of a predefined set of numbers.

Instructions:

Implement the getBasicStatistics() method in the StatisticsGenerator class.
In a StatisticsGeneratorTester class, create an instance of StatisticsGenerator, call getBasicStatistics(), and print the results.

7. Method with Object Parameters and a Return Value

Scenario: Create a class to compare two students’ grades and return the one with the higher grade.

Class Name: StudentComparator
Method: public Student getTopStudent(Student student1, Student student2)
Task: Write a method getTopStudent(Student student1, Student student2) that takes two Student objects as parameters and returns the Student object with the higher grade.

Instructions:

Implement the getTopStudent(Student student1, Student student2) method in the StudentComparator class.
In a StudentComparatorTester class, create instances of Student and test the method.

8. Method with Boolean Return Type

Scenario: Create a class to check if a number is even.

Class Name: NumberChecker
Method: public boolean isEven(int number)
Task: Write a method isEven(int number) that takes an integer as a parameter and returns true if the number is even, and false otherwise.

Instructions:

Implement the isEven(int number) method in the NumberChecker class.
In a NumberCheckerTester class, create an instance of NumberChecker and test the method with different numbers.

Exercises on When and Where to Use Methods (10 Exercises)

Here are 10 exercises focusing on the scenarios for using methods effectively.

1. Encapsulating Reusable Code

Scenario: Create a class to manage user input and output for a console application.

Class Name: ConsoleManager
Method: public void displayMenu() and public String getInput()
Task: Write a method displayMenu() to print a list of options, and a method getInput() to read and return the user’s choice.

Instructions:

Implement both methods in ConsoleManager.
Test them by simulating a menu-driven application in a ConsoleManagerTester class.

2. Encapsulating Reusable Code

Scenario: Create a class to handle the calculation of compound interest.

Class Name: InterestCalculator
Method: public double calculateCompoundInterest(double principal, double rate, int time)
Task: Write a method calculateCompoundInterest to calculate compound interest, which can be reused across multiple programs.

Instructions:

Implement the method in InterestCalculator.
Test it with various principal amounts, rates, and time periods in an InterestCalculatorTester class.

3. Improving Readability

Scenario: Create a class to handle transactions in a point-of-sale system.

Class Name: TransactionManager
Methods: public void addItem(double price), public double calculateTotal(), and public void printReceipt()
Task: Write methods to add items, calculate the total price, and print a receipt.

Instructions:

Implement all methods in TransactionManager.
Test the functionality in a TransactionManagerTester class by simulating a few transactions.

4. Improving Readability

Scenario: Create a class to process and display student grades.

Class Name: GradeProcessor
Methods: public void addGrade(int grade), public double calculateAverage(), and public void printGrades()
Task: Write methods to add grades, calculate the average, and print all grades.

Instructions:

Implement all methods in GradeProcessor.
Test the functionality in a GradeProcessorTester class by adding grades and displaying results.

5. Organizing Code

Scenario: Create a class to handle operations related to books in a library system.

Class Name: LibraryManager
Methods: public void addBook(Book book), public Book findBook(String title), and public void removeBook(String title)
Task: Write methods to add, find, and remove books from a collection.

Instructions:

Implement all methods in LibraryManager.
Test the functionality in a LibraryManagerTester class by adding, finding, and removing books.

6. Organizing Code

Scenario: Create a class to manage employee records in a company.

Class Name: EmployeeManager
Methods: public void addEmployee(Employee employee), public Employee findEmployeeById(String id), and public void printAllEmployees()
Task: Write methods to add employees, find employees by ID, and print all employee records.

Instructions:

Implement all methods in EmployeeManager.
Test the functionality in an EmployeeManagerTester class by managing a list of employees.

7. Simplifying Repetitive Tasks

Scenario: Create a class to handle user authentication.

Class Name: AuthManager
Method: public boolean authenticateUser(String username, String password)
Task: Write a method authenticateUser that checks user credentials and returns true if they match predefined values.

Instructions:

Implement the method in AuthManager.
Test it in an `AuthManager

Tester` class by simulating login attempts.

8. Simplifying Repetitive Tasks

Scenario: Create a class to validate form inputs.

Class Name: FormValidator
Methods: public boolean isEmailValid(String email), public boolean isPasswordStrong(String password)
Task: Write methods to validate an email address and a password.

Instructions:

Implement both methods in FormValidator.
Test them in a FormValidatorTester class by validating various email addresses and passwords.

9. Facilitating Testing and Debugging

Scenario: Create a class to perform basic file operations.

Class Name: FileManager
Methods: public void writeToFile(String filename, String content), public String readFromFile(String filename)
Task: Write methods to write to a file and read from a file.

Instructions:

Implement both methods in FileManager.
Test them in a FileManagerTester class by writing to and reading from a test file.

10. Facilitating Testing and Debugging

Scenario: Create a class to perform mathematical operations for a calculator app.

Class Name: MathOperations
Methods: public int add(int a, int b), public int subtract(int a, int b), public int multiply(int a, int b), public int divide(int a, int b)
Task: Write methods to perform basic arithmetic operations.

Instructions:

Implement all methods in MathOperations.
Test them in a MathOperationsTester class by performing various arithmetic operations.

Summary

These exercises cover different aspects of methods, including various combinations of parameters and return types, as well as scenarios for when and where to use methods. They will help you practice creating, organizing, and testing methods effectively in your Java programs.

Next Topic:

Go to Static to learn more with examples.