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Upcasting & Downcasting in Java with Examples | Full Tutorial

 

Upcasting & Downcasting in Java with Examples | Full Tutorial

Java is an object-oriented programming language that allows developers to create classes and objects. Upcasting and downcasting are two concepts that are related to class inheritance and object polymorphism.

Upcasting In Java and How Does It work?

It is a process of converting a subclass object to its superclass reference type. In other words, it is a way of treating an object of a subclass as an object of its superclass. This conversion is done implicitly by the Java Virtual Machine (JVM) at runtime.

When upcasting is performed, the subclass object loses its specific attributes and methods that are not present in its superclass. The resulting object can only access the methods and attributes that are defined in the superclass.

Upcasting is useful when you want to use a single reference type to refer to objects of different subclasses. This allows you to write more generic code that can handle different types of objects without having to write separate code for each type.

Example of Upcasting in Java

Let’s consider an example of upcasting in Java. Suppose we have a class hierarchy that looks like this:

class Animal 
{
public void makeSound()
{ System.out.println("Animal is making a sound"); }
}
class Dog extends Animal
{
public void makeSound()
{ System.out.println("Dog is barking");
}
public void fetch()
{
System.out.println("Dog is fetching");
}
}
Dog myDog = new Dog(); Animal myAnimal = myDog;

In this code, we create a Dog object called myDog. We then upcast myDog to an Animal reference called myAnimal. Now, myAnimal can only access the methods and attributes that are defined in the Animal class:

myAnimal.makeSound(); // prints “Dog is barking”

Good to Read:- Easiest Way to Learn What Is Garbage Collection In Java

Downcasting in Java and How Does It Work?

Downcasting is the opposite of upcasting. It is a process of converting a superclass reference type to its subclass object. In other words, it is a way of treating an object of a superclass as an object of its subclass. This conversion is done explicitly by the programmer using the cast operator.

When downcasting is performed, the superclass reference is checked to see if it refers to an object of the subclass. If it does, the reference is converted to the subclass type. If it doesn’t, a ClassCastException is thrown at runtime.

Downcasting is useful when you want to access the specific methods and attributes of a subclass object that are not present in its superclass. However, it should be used with caution because it can lead to runtime errors if the superclass reference does not refer to an object of the subclass.

Example of Downcasting in Java

Let’s consider an example of downcasting in Java. Suppose we have the same class hierarchy as before:

class Animal

{

public void makeSound()

{

System.out.println("Animal is making a sound");

}

}

class Dog extends Animal

{

public void makeSound()

{ System.out.println("Dog is barking");

}

public void fetch() {

System.out.println("Dog is fetching");

}

}

Now, let’s create an Animal object and downcast it to a Dog reference:

Animal myAnimal = new Dog(); Dog myDog = (Dog) myAnimal;

In this code, we create an Animal object called myAnimal. We then downcast myAnimal to a Dog reference called myDog. Now, myDog can access the specific methods and attributes that are defined in the Dog class:

myDog.makeSound(); // prints “Dog is barking” myDog.fetch(); // prints “Dog is fetching”

Difference Between Upcasting and Downcasting

The main difference between upcasting and downcasting is the direction of the conversion. Upcasting converts a subclass object to its superclass reference, while downcasting converts a superclass reference to its subclass object.

Upcasting is done implicitly by the JVM at runtime, while downcasting is done explicitly by the programmer using the cast operator.

It is safe because it only allows access to the methods and attributes that are defined in the superclass. Downcasting, on the other hand, can be dangerous because it can lead to runtime errors if the superclass reference does not refer to an object of the subclass.

Good to Read:- Top Features of JavaScript You Must Know

When to Use Upcasting and Downcasting in Java?

Upcasting is useful when you want to write generic code that can handle different types of objects without having to write separate code for each type. It is also useful when you want to create collections of objects that have a common superclass.

Downcasting is useful when you want to access the specific methods and attributes of a subclass object that are not present in its superclass. However, it should be used with caution because it can lead to runtime errors if the superclass reference does not refer to an object of the subclass.

Best Practices for Upcasting and Downcasting in Java

Here are some best practices for using upcasting and downcasting in Java:

  • Use upcasting to write generic code that can handle different types of objects without having to write separate code for each type.
  • Use downcasting sparingly and only when you need to access the specific methods and attributes of a subclass object that are not present in its superclass.
  • Always check the type of the object before downcasting to avoid runtime errors.
  • Avoid using downcasting in performance-critical code because it can be slow.

Common Mistakes to Avoid When Using Upcasting and Downcasting in Java

Here are some common mistakes to avoid when using upcasting and downcasting in Java:

  • Using downcasting without checking the type of the object first can lead to runtime errors.
  • It excessively can make the code difficult to read and maintain.
  • Using upcasting with complex object hierarchies can result in unexpected behavior.
  • Forgetting to cast the object before downcasting can also lead to runtime errors.

Good to Read:- Difference Between C++ and Java | C++ Vs Java

Conclusion

In conclusion, upcasting and downcasting are two important concepts in Java that allow developers to work with class inheritance and object polymorphism. Upcasting is the process of converting a subclass object to its superclass reference, while downcasting is the process of converting a superclass reference to its subclass object.

Upcasting is useful for writing generic code that can handle different types of objects, while downcasting is useful for accessing the specific methods and attributes of a subclass object that are not present in its superclass. However, downcasting should be used with caution because it can lead to runtime errors.

A skilled Java developer can bring your ideas to life and ensure that your software runs smoothly and seamlessly. Don’t wait any longer to take your business to the next level — hire a Java developer now and start building the applications that will help you succeed!


TestCraft: Codeless Automation Platform

 

TestCraft: Codeless Automation Platform

TestCraft

TestCraft is an automation test platform for continuous and regression testing for web applications. It comes with AI (Artificial Intelligence) to overcome the budget cost and less maintenance time with automatic control of the changes in the app.

Test engineers can create selenium-based and automated tests in Craft Testing by drag and drop interface.

It runs on multiple browser platforms and work environments without any problem.

Coding Vs Manual

Selenium is an open-source automation framework for web applications. This is a widely used tool for test automation by QA. It has some disadvantages also like it does not support mobile automation. TestCraft with selenium fully fulfills this drawback of selenium.

The overview to selenium code automation is a costly processes that need many changes and long processes for the organizations. The best way to move is to first overpass the gap between manual and coding tests by letting manual testers use tools like TestCraft. By this manual testers can control when selenium code is automatically created.

Features of TestCraft

  • Super Simple — It has a beautiful and intuitive UI and smooth design user experience, no dev skills are required to master in TestCraft.
  • DevOps Friendly — Test craft is purely Saas and testing becomes an integral part of the agile process.
  • Low Maintenance — It requires low maintenance and a unique on-the-fly mechanism fixes issues during run time.
  • Fast — Quick and fast setup and rapid test creation. The framework is not required.
  • Multi-Platform — It runs tests simultaneously on different and multiple platforms & work environments.
  • AI-Powered automation — In this, AI and machine learning technology automatically detect and overcome changes in the app. This reduces the time and effort required.
  • Codeless Automation — It uses a codeless automation approach which means users do not need programming to create and run automation tests. This also provides drag and drop to create test scenarios easily and quickly.
  • Integrations — It can integrate with different software development tools like Jenkins, Selenium, and Jira. This allows users to run testing processes and improve collaboration.

How TestCraft works?

TestCraft uses codeless and AI automation approaches that allow users to create automated tests with visual elements. In this platform, AI automation features automatically detect and make the changes in the app under test and reduce time and effort.

1) Test Craft Signup

The first step is to sign up with Test Craft for a free or a subscription purchase.

2) Create Project

After completing the signup process, users can create a new project in the Test Craft. It allows the users to create the projects and manage them efficiently.

3) Cretae a Test Scenario

After creating a project, users can start creating test cases and scenarios. Its visual features allow users to create tests easily and quickly using visual elements like icons, images, and screenshots with drag and drop interface.

4) Run Test Scenario

After creating the test scenarios, users can execute the test scenarios to check whether they work as expected or not. Its AI automation feature automatically detects and modifies the changes in the app and ensures that the test scenario runs reliably and accurately.

8) Analyze the Result

After executing the test scenario, users can analyze the resulting outcome to ensure and identify the defects, bugs, or errors in the application flow. It also provides different analytic tools by which users can identify issues efficiently and quickly. Our experts have written a guide on the difference between bugs and defects. Feel free to checkout!

9) Fix the Issues

Now After analyzing the result, users can fix the issues that are identified by the testing process. Its integration feature helps to communicate and collaborate effectively and ensures that every user is on the same page.

Test Dropdown List in TestCraft

Dropdown lists are generally the key element of the web and navigate with them online. Some automation tools and recorders are unable to validate attributes of dropdown lists. Testing dropdowns in TestCrafts are simple and easy to use. Include a dropdown list which is part of the flow and select the value to be tested



Flow is simple which is done by using drag and drop or on live by running the app, clicking and pointing the elements in the flow. A new test model will be created which you can then run on different browsers and work environments.



Test Automation on Health Care

The need for test automation to maintain a faster release cycle has significantly increased as a result of the digital transformation of the healthcare sector.

Many healthcare organizations use TestCraft for their test automation platform to meet their business requirements without reshuffling their existing teams. QA successfully scaled up his test automation by implementing Test Craft and shortening the release cycle by 50% while maintaining the throughput.



Advantages of Test Craft

  • Save time and cost.
  • Increase efficiency and accuracy.
  • Reduces errors and defects.
  • Improve collaboration and communication.

Disadvantages of Test Craft

  • Limited Platform support
  • Limited customization
  • Complex initial setup.

Conclusion

TestCraft is a software testing platform that provides a range of benefits with cost-saving, accuracy, and efficiency. Its codeless automation and AI automation features help to create and maintain automated tests and allow teams to other major aspects of the development process. Overall TestCraft is an attractive option for improving the web apps testing process and their development flow.

Testing with AI: Post 3

-------------------------

Continuing my Testing with AI series, today I’m sharing another amazing AI-powered assistant in software testing—TestCraft.


What is TestCraft? In their own words:

============================

TestCraft is a Chrome extension designed to be a companion to your software testing. With TestCraft, you can select UI elements directly from your browser and leverage the capabilities of large language models (LLMs) to generate innovative test ideas, write automation scripts across various frameworks and programming languages, and perform accessibility checks.


What makes TestCraft special?

============================

1) It’s open source—easy to start, and free to explore.

2) You can install it as a Chrome extension, select elements directly on the page, and automate them effortlessly.

3) It supports popular frameworks like Cypress, Selenium, and Playwright.

4) Programming languages supported: JavaScript, TypeScript, Java, C#, and Python.


My experience with TestCraft:

======================

I tried using it with Cypress and JavaScript, and here’s what I found:


(1) It automatically generated a variety of test cases, including edge cases, which saved me a lot of time.


(2) The tool provided a great starting point, though some minor tweaks were needed—particularly around error messages. But honestly, that wasn’t a big deal.


(3) For beginners in automation, this tool is fantastic, offering a solid base on which to build.


(4) Even experienced testers will find it useful, as it generates a comprehensive list of test cases, saving time on repetitive tasks.


The best part? It’s so simple to use! Just install the extension, select elements on the page, and let TestCraft do the rest.


While it’s not perfect yet (minor adjustments are required), it’s worth trying out. I’ve attached some screenshots from my experience with the tool to give you an idea.