Abstract classes are an important concept in object-oriented programming (OOP) and are widely used in Java. They are classes that cannot be instantiated, but can be inherited by other classes. Abstract classes can have both abstract and non-abstract methods, and they provide a way to define a set of methods that must be implemented by any class that inherits from them.
To master the concept of abstract classes, it is important to practice implementing them in Java. In this article, we will present practice problems on abstract classes in Java that will help you gain a better understanding of this concept. If you have any doubts regarding abstract classes, you can refer to our article “Abstract Class in Java” which provides a detailed explanation along with examples. With these practice problems, you can improve your Java programming skills and become more confident in using abstract classes in your projects.
Let’s start practicing :
| Create an abstract class “Vehicle” with abstract methods “start()” and “stop()”. Implement two subclasses “Car” and “Motorcycle” which extend “Vehicle” and implement the abstract methods. Create a “Driver” class which contains a list of “Vehicle” objects. Add methods to the “Driver” class to start and stop all vehicles. Create objects of all classes and test their behavior. |
| Solution : Click here to view answer. |
| Create an abstract class “Shape” with abstract methods “getArea()” and “getPerimeter()”. Implement two subclasses “Rectangle” and “Circle” which extend “Shape” and implement the abstract methods. Create a “Square” class which extends “Rectangle” and overrides the necessary methods. Create objects of all classes and test their behavior. |
| Solution : Click here to view answer. |
| Create an abstract class “Employee” with abstract methods “calculateSalary()” and “displayEmployeeDetails()”. Implement two subclasses “Manager” and “Worker” which extend “Employee” and implement the abstract methods. Create a “SalesPerson” class which extends “Manager” and overrides the necessary methods. Create objects of all classes and test their behavior. |
| Solution : Click here to view answer. |
| Create an abstract class “BankAccount” with abstract methods “deposit()” and “withdraw()”. Implement two subclasses “SavingsAccount” and “CheckingAccount” which extend “BankAccount” and implement the abstract methods. Create a “Customer” class which contains a list of “BankAccount” objects. Add methods to the “Customer” class to display account balances, deposit/withdraw money, etc. Create objects of all classes and test their behavior. |
| Solution : Click here to view answer. |
| Create an abstract class “Account” with abstract method “calculateInterest()”. Implement two subclasses “SavingsAccount” and “CurrentAccount” which extend “Account” and implement the “calculateInterest()” method. Create objects of both classes and test their behavior. |
| Solution : Click here to view answer. |
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An abstract class called “Marks” is needed to calculate the percentage of marks earned by students A in three subjects (with each subject out of 100) and student B in four subjects (with each subject out of 100). This class must contain the abstract method “getPercentage,” which two other classes, “A” and “B,” will inherit. The method “getPercentage,” which provides the percentage of students, is shared by classes “A” and “B.” The constructor of class ‘A’ will accept the marks obtained in three subjects as its parameters and the constructor of class ‘B’ will accept the marks obtained in four subjects as its parameters. To test the implementation, objects for both the classes need to be created and the percentage of marks for each student should be printed. |
| Solution : Click here to view answer. |
In conclusion, abstract classes are an important feature of Java programming that allow for the creation of a blueprint for other classes to follow. By practicing with abstract classes and implementing abstract methods, you can improve your Java programming skills and gain a better understanding of how to use this feature effectively in your code. Through the practice problems mentioned in this article, you can learn how to create and use abstract classes in Java, and apply them to different scenarios.
If you still have any doubts regarding abstract classes or any other Java-related topics, feel free to leave your questions in the comment box. Our team will do our best to answer your queries and help you improve your understanding of Java programming. Happy coding!
