How to create an instance of abstract class in Java

This article aims to explain how to create an instance of an abstract class in Java. We will look at the different ways to create an instance of an abstract class and the pros and cons of each approach. We will also discuss the importance of understanding the underlying concepts of abstract classes and the implications of creating an instance of an abstract class.

Creating an instance of an abstract class can be done in a few different ways. The most common way is to create a concrete subclass of the abstract class and then instantiate that subclass. This is the most common way because it allows the subclass to implement all of the abstract methods of the parent class.

What is an Abstract Class?

A unique class type in Java that cannot be instantly created is known as an abstract class. A class that has abstract methods-methods without an implementation-is said to be abstract. Concrete classes, or classes that offer an implementation for every abstract method, are intended to be added to abstract classes in order to increase their functionality.

1. Create the abstract class first. An abstract class must first be created before an instance of it can be created. All the abstract methods that the abstract class's concrete subclasses must implement should be defined. It should also include any extra features or information that all subclasses will share.
2. Making a Concrete Subclass The creation of a concrete subclass of the abstract class is the following stage. The abstract class's declared abstract methods must all be implemented by the concrete subclass. Any other features or information unique to the subclass should also be included.
3. Create the Subclass Once the concrete subclass has been generated, an instance of the abstract class can be created by instantiating the concrete subclass. Calling the function Object() of the concrete subclass and giving any appropriate arguments accomplishes this. After being created, the instance can be utilized just like any other object.
   Abstract classes in Java cannot be instantiated independently but can be subclassed. An instance of an abstract class can only be created through inheritance. To create an instance of an abstract class, you need to create a concrete subclass of the abstract class and then instantiate the concrete subclass.
   Abstract classes can be used to create a variety of object-oriented software.
4. Database Access: Abstract classes can create a set of classes responsible for accessing a database. The abstract class can define the methods necessary for interacting with the database, such as connecting, querying, and updating.
5. Network Protocols: Abstract classes can create a set of classes responsible for handling different network protocols. The abstract class can define the methods for interacting with the protocol, such as sending and receiving messages. The subclasses can then use the methods defined in the abstract class to handle the various protocols.
6. User Interface Components: Abstract classes can be used to create a set of classes responsible for constructing user interface components. The abstract class can define the methods necessary for constructing the components, such as positioning, sizing, and drawing. The subclasses can then use the methods defined in the abstract class to construct the components.

Here is a simple example:

Filename: Abst.java

Output:

Drawing Circle

In this example, Shape is an abstract class that contains an abstract method draw(). The Circle class extends the Shape class and implements the draw() method.

To create an instance of the abstract class, we create an instance of the concrete subclass Circle and assign it to a reference of type Shape. This is because a concrete subclass is also considered an instance of its superclass.

When we call the draw() method on the shape reference, it invokes the implementation in the Circle class, which prints "Drawing Circle" to the console.

How to Create an Instance of an Abstract Class

Java does not allow the direct instantiation of abstract classes. Hence it is not feasible to create an instance of an abstract class. However, there are a few ways to create an instance of an abstract class indirectly, by using a concrete subclass or an anonymous class.

Using a Concrete Subclass

The most common way to create an instance of an abstract class is to use a concrete subclass. To do this, you first need to create a concrete subclass that implements all of the abstract methods in the abstract class. Following that, you can make an instance of this concrete subclass and use it in place of an instance of the abstract class.

The fact that you also generate an instance of the superclass when you create an instance of a concrete subclass must be kept in mind. In other words, you can use the reference to the concrete subclass to access methods and fields in the superclass.

But it is possible to make an instance of an abstract class. Utilizing a factory technique is one option. A factory method is a technique for producing things of a particular sort. It is a technique for encapsulating object creation so that clients do not need to understand how to do it themselves.

Let's imagine, for illustration, that we have an abstract class called Animal. The animal is an abstract class that defines the properties and behaviors of animals. We could create a factory method called create animal () that takes in an argument specifying the type of animal to create. They create animal () method would then return an instance of the specified animal type.

A class loader is a Java class responsible for loading classes from a given source, such as a file or the network. A class instance can be created after the class loader has loaded an abstract class.

Abstract classes are a powerful tool for designing object-oriented software. They allow developers to create a set of related classes that all share the same basic structure while allowing each subclass to have its own unique behavior. While it is impossible to create an instance of an abstract class, there are a few ways to use them, such as creating a subclass of the abstract class and defining an interface.

Using an Anonymous Class

Using an anonymous class is another method for producing an instance of an abstract class. An instance of an abstract class can be created using an anonymous class, which is a class that is declared without a name.

Advantages and Disadvantages of Creating an Instance of an Abstract Class

In some circumstances, such as when a concrete subclass is unavailable or when you want to create an abstract class instance without establishing a concrete subclass, creating an instance of an abstract class might be advantageous. However, there are some important considerations that you should keep in mind when creating an instance of an abstract class.

The main advantage of using a concrete subclass to create an instance of an abstract class is that it is easy to read and understand. It also allows you to create an instance of an abstract class without having to write any additional code.

However, the main disadvantage of using a concrete subclass to create an instance of an abstract class is that it can lead to tight coupling between the concrete subclass and the abstract class. Future maintenance and code modifications may become challenging as a result.

On the other side, the key benefit of generating an instance of an abstract class using an anonymous class is that you can do so without first building a concrete subclass. When the concrete subclass is unavailable or you wish to make an instance of an abstract class without constructing a concrete subclass, this can be helpful.

The main disadvantage of using an anonymous class to create an instance of an abstract class is that it requires more code and is more difficult to read. It also makes it difficult to maintain and modify the code in the future.

Conclusion

Creating an instance of an abstract class is not possible in Java, but there are a few ways to create an instance of an abstract class indirectly, by using a concrete subclass or an anonymous class. Each approach has its own advantages and disadvantages, so it is important to understand the underlying concepts of abstract classes and the implications of creating an instance of an abstract class before deciding which approach to use.