Questions and Answers
Explain the concept of inheritance in Java and provide an example of its use.
Inheritance in Java allows a class to inherit the properties and behaviors of another class. An example of inheritance in Java is a subclass inheriting from a superclass, such as a 'Dog' class inheriting from an 'Animal' class.
Discuss the advantages and disadvantages of using inheritance in Java, providing specific examples for each.
One advantage of inheritance in Java is code reusability, where common attributes and methods can be shared across classes. However, a disadvantage is that it can lead to tight coupling between classes, making the code harder to maintain and modify.
Explain the use of the 'super' keyword in Java inheritance and provide a scenario where it would be useful.
The 'super' keyword in Java is used to refer to the immediate parent class instance. It is useful when the subclass overrides a method of the superclass and still wants to call the overridden method. For example, when a subclass 'Square' overrides the 'area' method of its superclass 'Rectangle' and still wants to calculate the area based on the superclass implementation, it can use the 'super' keyword.
Study Notes
Inheritance in Java
- Inheritance is a mechanism in Java that allows one class to inherit properties and behavior of another class.
- The child class, also known as the subclass, inherits the fields and methods of the parent class, also known as the superclass.
Advantages of Inheritance
- Code reusability: Inheritance allows for code reusability, as the child class can inherit the common attributes and methods of the parent class.
- Reduced code duplication: Inheritance helps reduce code duplication, as the child class can inherit the common code from the parent class.
- Easier maintenance: Inheritance makes it easier to maintain code, as changes to the parent class are automatically reflected in the child class.
Disadvantages of Inheritance
- Tight coupling: Inheritance can lead to tight coupling between the parent and child classes, making it difficult to change one class without affecting the other.
- Fragile base class problem: Inheritance can lead to the fragile base class problem, where changes to the parent class can break the child class.
- Overriding vs. Hiding: Inheritance can lead to confusion between overriding and hiding methods, which can cause errors if not handled properly.
The 'super' Keyword in Java Inheritance
- The 'super' keyword is used to access the members (methods and fields) of the parent class from the child class.
- The 'super' keyword can be used to call the parent class constructor, methods, and variables from the child class.
- Scenario: When a child class wants to extend the behavior of a parent class method, it can use the 'super' keyword to call the parent class method and then add its own implementation.
Example of Inheritance in Java
- A simple example of inheritance in Java is a rectangle and a square class, where the square class inherits the properties of the rectangle class and adds its own implementation for the setWidth() and setHeight() methods.
- The square class can use the 'super' keyword to call the setWidth() and setHeight() methods of the rectangle class and then set the width and height equal to each other.
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