Difference between Thread vs Runnable interface in Java

 In Java, both the Thread class and the Runnable interface are used for creating and managing concurrent threads of execution. They serve similar purposes but differ in their implementation approach. Here are the key differences between the two:

Inheritance vs Interface: The Thread class is a concrete class that extends the java.lang.Thread class, making it capable of directly creating and managing threads. On the other hand, the Runnable interface is implemented by a class, and the class can be used to create a Thread object using the Runnable instance.

Extending vs Implementing: To create a thread using the Thread class, you need to extend it and override its run() method. This allows you to define the code that will be executed in the thread. In contrast, to use the Runnable interface, you need to implement the run() method in a separate class. The run() method contains the code that will be executed when the thread is started.

Reusability: The use of Runnable interface provides better reusability than extending the Thread class. With Runnable, you can implement the interface in multiple classes and create threads from different instances of those classes. This promotes a more flexible and modular design by separating the task logic from the thread management.

Single Inheritance Constraint: Java allows a class to extend only one class, which means if you extend the Thread class, you cannot extend any other class. However, by implementing the Runnable interface, you can still extend another class and implement Runnable, as Java supports multiple interfaces.

Encapsulation: Implementing Runnable separates the task (defined in the run() method) from the thread's behavior, allowing better encapsulation. It enables you to pass the Runnable instance to different thread constructors, promoting code reuse and modularity.

Resource Sharing: When multiple threads need to share resources or data, implementing Runnable is generally preferred. By passing the same instance of the Runnable implementation to multiple threads, they can access and manipulate shared resources easily. In contrast, extending the Thread class may lead to limitations in resource sharing.

In summary, the Thread class provides a convenient way to create and manage threads, while the Runnable interface offers a more flexible and reusable approach to defining thread behavior. The choice between the two depends on the specific requirements of your application and the design principles you want to follow.

What is Timer and TimerTask in Java – Tutorial Example

In Java, the Timer and TimerTask classes are used for scheduling tasks to be executed at a specified time or after a specific interval. These classes provide a convenient way to perform time-based operations in Java applications. This tutorial will introduce you to the Timer and TimerTask classes and demonstrate their usage through an example.

Timer Class

The Timer class in Java provides a facility for scheduling tasks to be executed at a specified time or after a certain delay. It is part of the java.util package and was introduced in JDK 1.3. The Timer class internally uses a single background thread to execute scheduled tasks.

To use the Timer class, you need to create an instance of it and schedule tasks using its schedule() or scheduleAtFixedRate() methods. The schedule() method is used to schedule a task to be executed once, while the scheduleAtFixedRate() method is used to schedule a task to be executed repeatedly at fixed intervals.

TimerTask Class

The TimerTask class is an abstract class that represents a task to be scheduled by a Timer. To use the TimerTask class, you need to create a subclass and override its run() method. The run() method contains the code that will be executed when the task is triggered.

Example: Scheduling a Task

Let's see an example that demonstrates how to use the Timer and TimerTask classes to schedule a task in Java:

import java.util.Timer;
import java.util.TimerTask;

public class TaskScheduler {
    public static void main(String[] args) {
        TimerTask task = new TimerTask() {
            @Override
            public void run() {
                System.out.println("Task executed!");
            }
        };

        Timer timer = new Timer();
        timer.schedule(task, 5000); // Schedule the task to be executed after 5 seconds
    }
}

In the above example, we create a TimerTask subclass by overriding its run() method, which simply prints "Task executed!" to the console. We then create an instance of the Timer class and schedule the task using the schedule() method, specifying a delay of 5000 milliseconds (5 seconds). 

When you run this program, it will wait for 5 seconds and then execute the task, printing "Task executed!" to the console. 

Cancelling a Task 

If you want to cancel a scheduled task before it is executed, you can use the Timer class's cancel() method. 

Here's an example that demonstrates task cancellation:

import java.util.Timer;
import java.util.TimerTask;

public class TaskScheduler {
    public static void main(String[] args) {
        TimerTask task = new TimerTask() {
            @Override
            public void run() {
                System.out.println("Task executed!");
            }
        };

        Timer timer = new Timer();
        timer.schedule(task, 5000); // Schedule the task to be executed after 5 seconds

        // Cancel the task after 3 seconds
        timer.schedule(new TimerTask() {
            @Override
            public void run() {
                task.cancel();
                System.out.println("Task cancelled!");
            }
        }, 3000);
    }
}

In this example, we schedule a task to be executed after 5 seconds, but we also schedule another task to cancel the first task after 3 seconds. When you run this program, you will see that "Task cancelled!" is printed to the console before "Task executed!" because the cancellation task runs earlier. 

Conclusion 

The Timer and TimerTask classes in Java provide a convenient way to schedule tasks to be executed at specific times or after certain intervals. By using these classes, you can

Difference between Wait and Sleep, Yield in Java? Example

In Java, "wait," "sleep," and "yield" are three different concepts used for different purposes. 

1. Wait:

The wait() method is used in Java for thread synchronization. When a thread calls the wait() method on an object, it releases the lock it holds on that object and waits until another thread notifies it to resume. This is typically used in multi-threaded environments where threads need to coordinate their activities. 

Here's an example of using wait() and notify() to synchronize threads:

class Message {
   private String message;
   
   public synchronized void setMessage(String message) {
      this.message = message;
      notify(); // Notify waiting threads
   }
   
   public synchronized String getMessage() throws InterruptedException {
      while (message == null) {
         wait(); // Wait until message is available
      }
      String msg = message;
      message = null;
      return msg;
   }
}

2. Sleep: 

The sleep() method is used to pause the execution of the current thread for a specified period of time. It is typically used for introducing delays or to control the timing of certain operations in a program. 

Here's an example of using sleep() to introduce a delay:

public class SleepExample {
   public static void main(String[] args) {
      System.out.println("Before sleep");
      try {
         Thread.sleep(2000); // Sleep for 2 seconds
      } catch (InterruptedException e) {
         e.printStackTrace();
      }
      System.out.println("After sleep");
   }
}

In the above example, the program pauses for 2 seconds before printing "After sleep". 

3. Yield:

The yield() method is used to give a hint to the scheduler that the current thread is willing to give up its current execution time to allow other threads of the same priority to run. 

However, it's up to the scheduler to decide whether to honor this hint or not. 

Here's an example of using yield():

public class YieldExample {
   public static void main(String[] args) {
      Thread t1 = new Thread(() -> {
         for (int i = 0; i < 5; i++) {
            System.out.println("Thread 1: " + i);
            Thread.yield(); // Yield execution to other threads
         }
      });
      
      Thread t2 = new Thread(() -> {
         for (int i = 0; i < 5; i++) {
            System.out.println("Thread 2: " + i);
            Thread.yield(); // Yield execution to other threads
         }
      });
      
      t1.start();
      t2.start();
   }
}

In the above example, two threads, t1 and t2, are created and both invoke yield() after printing each number. This gives the scheduler an opportunity to switch between the threads during execution, although the actual behavior depends on the underlying system's scheduling algorithm. 

Overall, wait() and notify() are used for thread synchronization, sleep() is used for introducing delays, and yield() is used to suggest the scheduler to give other threads a chance to run.

Top 5 courses to learn Solr in 2023 - Best of Lot

In 2023, there are several great courses available to learn Apache Solr, a widely-used search platform. Here are the top five courses to consider:

"Apache Solr for Developers" by Lucidworks: This comprehensive course covers the fundamentals of Solr, including indexing, querying, and relevance tuning. It also delves into advanced topics such as distributed searching and scaling Solr clusters.

"Solr in Action" by Manning Publications: This course provides hands-on experience with Solr through real-world examples and practical exercises. It covers topics such as schema design, document processing, and SolrCloud deployment.

"Apache Solr Training" by Simplilearn: This instructor-led course offers a deep dive into Solr's architecture and features. It covers topics such as data indexing, advanced query techniques, and integration with other tools and technologies.

"Solr Search Server" by Pluralsight: This course provides a comprehensive overview of Solr, including its installation, configuration, and usage. It covers topics such as full-text search, faceted navigation, and advanced indexing techniques.

"Apache Solr 8.x Developer Certification Training" by Edureka: This course focuses on preparing learners for the Apache Solr 8.x Developer Certification exam. It covers essential Solr concepts and features, including core administration, querying, and indexing strategies.

These courses offer different approaches and depth of content, so you can choose based on your learning preferences and goals. Additionally, it's worth exploring official documentation and community resources for Apache Solr, as they can provide valuable insights and examples to complement your learning journey.

Top 5 Courses For ISTQBA Certified Tester in 2023 - Best of Lot

In the ever-evolving field of software testing, staying updated with the latest knowledge and skills is crucial for professionals. One of the most recognized certifications in the industry is the ISTQB® (International Software Testing Qualifications Board) Certified Tester certification. For testers looking to enhance their expertise and boost their career prospects in 2023, we have compiled a list of the top five courses that are considered the best in the field.

Advanced Level Test Manager (CTAL-TM):

The Advanced Level Test Manager course is designed for experienced testers who wish to expand their managerial skills and take on leadership roles in the testing domain. This course delves into advanced topics such as test management processes, test estimation and planning, test monitoring and control, and defect management. It equips professionals with the knowledge and techniques required to effectively manage testing projects and teams, ensuring high-quality software delivery.

Advanced Level Test Automation Engineer (CTAL-TAE):

As the demand for test automation continues to rise, the Advanced Level Test Automation Engineer course provides testers with the necessary skills to design, develop, and maintain automated testing solutions. This course focuses on advanced automation concepts, including test automation architectures, frameworks, and tools. Testers will learn how to select appropriate automation approaches, create robust test scripts, and integrate automation into the software development lifecycle, resulting in efficient and effective testing processes.

Agile Tester Extension (CTFL-AT):

With the increasing adoption of Agile methodologies, the Agile Tester Extension course is a must-have for testers working in Agile environments. This course explores the unique challenges and opportunities in Agile testing, emphasizing collaboration, continuous feedback, and iterative testing approaches. Testers will gain insights into Agile principles, methods, and techniques, enabling them to contribute effectively to Agile teams and ensure high-quality software delivery in dynamic and fast-paced development cycles.

Performance Testing (CTFL-PT):

Performance testing plays a critical role in assessing the responsiveness, scalability, and stability of software systems. The Performance Testing course provides testers with the knowledge and skills required to plan, design, and execute performance tests effectively. It covers various performance testing techniques, tools, and best practices, enabling testers to identify performance bottlenecks, analyze system behavior under different loads, and optimize software performance. This course is invaluable for testers involved in ensuring the performance and reliability of applications.

Mobile Application Testing (CTFL-MAT):

With the exponential growth of mobile applications, specialized knowledge in mobile testing is highly sought after. The Mobile Application Testing course equips testers with the skills to test mobile apps across different platforms, devices, and networks. It covers the unique challenges of mobile testing, including usability, performance, security, and compatibility. Testers will learn about mobile testing strategies, tools, and emerging trends, enabling them to effectively test mobile applications and deliver exceptional user experiences.

Conclusion:

For ISTQB® Certified Testers looking to stay at the forefront of the software testing industry in 2023, the above-mentioned courses are the top recommendations. These courses provide specialized knowledge and skills in areas such as test management, test automation, Agile testing, performance testing, and mobile application testing. By investing in these courses, testers can enhance their professional capabilities, expand their career opportunities, and contribute to the success of software projects in an increasingly competitive landscape. Stay ahead of the curve by enrolling in these courses and taking your testing expertise to new heights.