Summary: In this Article, you will learn about Java. What is a inheritance in Java? What are the 4 types of inheritance in Java? What is pol...
Summary:
In this Article, you will learn about Java.
- What is a inheritance in Java?
- What are the 4 types of inheritance in Java?
- What is polymorphism in Java?
- What is encapsulation in Java?
- What are the 4 types of polymorphism in Java?
Read more to know each in detail.
Q1. What is an inheritance in Java?
Inheritance in Java is a mechanism by which a class (called the subclass or child class) can inherit properties and methods from another class (called the superclass or parent class). The subclass can also add new properties and methods, as well as override inherited methods, to create a specialized version of the superclass.
Inheritance is implemented using the "extends" keyword in Java. For example, if class A is the superclass and class B is the subclass, class B would be defined as:
class B extends A {
// properties and methods of class B
}
This allows class B to inherit all the properties and methods of class A, and also allows class B to have its own properties and methods. Inheritance also allows for polymorphism, which means that a subclass can be used in the same way as its superclass, allowing for more flexibility in code reuse.
Inheritance also allows to use the overriding technique where a subclass can change the implementation of a method that is already defined in the superclass.
It should be noted that Java does not support multiple inheritance, which means that a class can only inherit from a single superclass. However, it does support interface implementation which allows a class to inherit from multiple interfaces.
Q2. What are the 4 types of inheritance in Java?
In Java, there are four main types of inheritance:
Single inheritance: This is the most basic type of inheritance, where a class (the subclass) inherits properties and methods from a single class (the superclass). This is implemented using the "extends" keyword, as described in the previous answer.
Multi-level inheritance: This type of inheritance occurs when a subclass inherits from a superclass, which in turn inherits from another superclass. This creates a hierarchy of classes, with properties and methods being passed down through multiple levels.
Hierarchical inheritance: This type of inheritance occurs when multiple subclasses inherit from a single superclass. In this case, the properties and methods of the superclass are shared among all the subclasses, but each subclass can also have its own unique properties and methods.
Multiple inheritance: This type of inheritance occurs when a class inherits properties and methods from multiple classes. However, Java does not support multiple inheritance, where a class can directly inherit from multiple classes. However, it does support interface implementation which allows a class to inherit from multiple interfaces.
It's worth noting that the last type is not directly supported by Java, but it can be achieved using interface or using a design pattern like the decorator pattern.
Q3. What is polymorphism in Java?
Polymorphism in Java is a concept that allows objects of different classes to be treated as objects of a common superclass. This means that a method or variable that is defined in the superclass can be used with objects of any class that inherits from that superclass.
There are two types of polymorphism in Java:
Compile-time polymorphism: This type of polymorphism is also known as method overloading. It allows a class to have multiple methods with the same name, but with different parameters. When a method is called, the Java compiler determines which version of the method to call based on the number and types of the arguments passed to the method.
Run-time polymorphism: This type of polymorphism is also known as method overriding. It allows a subclass to provide a different implementation of a method that is already defined in its superclass. When a method is called on an object, the Java runtime will determine which version of the method to call based on the actual type of the object at runtime.
Polymorphism allows for more flexibility in code reuse, as objects of different classes can be treated as objects of a common superclass, and the same method can be used with objects of any of those classes. Polymorphism is one of the key concepts of object-oriented programming, and it enables the use of dynamic binding in Java, which allows objects to decide for themselves which method to execute at runtime.
Q4. What is encapsulation in Java?
Encapsulation in Java is a mechanism by which the inner workings of an object are hidden from the outside world, and can only be accessed through a set of well-defined interfaces (usually public methods). This allows for the implementation details of an object to be changed without affecting the rest of the program, and it promotes the idea of data hiding and information hiding.
Encapsulation is implemented in Java using the concept of classes and objects, and by using the access modifiers "private," "protected" and "public".
When a class variable or method is declared as private, it can only be accessed within the same class, not by any other class, this ensures that the data within the class is protected and can only be accessed through public methods, which act as an interface to the outside world.
The "protected" modifier allows access to the class members from within the package and from the subclasses.
The "public" modifier allows access to the class members from anywhere.
Encapsulation is one of the fundamental concepts of object-oriented programming, and it helps to create more maintainable and robust code by ensuring that the internal state of an object is protected from unwanted access or modification.
Encapsulation also enables the use of abstraction, which allows the developer to focus on the interface of an object, rather than its implementation details, making the code more readable and understandable.
Q5. What are the 4 types of polymorphism in Java?
There are actually two types of polymorphism in Java, Compile-time polymorphism and Run-time polymorphism, not four.
Compile-time polymorphism: This type of polymorphism is also known as method overloading. It allows a class to have multiple methods with the same name, but with different parameters. When a method is called, the Java compiler determines which version of the method to call based on the number and types of the arguments passed to the method.
Run-time polymorphism: This type of polymorphism is also known as method overriding. It allows a subclass to provide a different implementation of a method that is already defined in its superclass. When a method is called on an object, the Java runtime will determine which version of the method to call based on the actual type of the object at runtime.
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