Difference Between Thread and Runnable in Scala

In the realm of concurrent programming, particularly in Scala, the concepts of Thread and Runnable often come to the forefront. Both are pivotal for implementing multithreading, a technique that allows concurrent execution of two or more parts of a program for maximum utilization of the CPU. Here, we delve deep into the nuances that differentiate Thread and Runnable and shed light on when to use which.

Understanding Multithreading

Multithreading is the concurrent execution of multiple threads to enhance the efficiency of a program. A thread, in simple terms, is the smallest unit of a process that can run concurrently with other threads. It's like having multiple workers (threads) working on different parts of a task simultaneously, ensuring that the task gets completed faster and more efficiently.

In Scala, there are primarily two ways to create threads:

1. By extending the Thread class.
2. By implementing the Runnable interface.

While both approaches serve the purpose of multithreading, they have distinct characteristics and use cases.

Thread vs. Runnable: The Key Differences

1. Nature and Type

• Thread: It is a class in Scala. When you extend the Thread class, you are essentially creating a new thread that can run concurrently with other threads.
• Runnable: On the other hand, Runnable is a functional interface. It's not a thread in itself but can be passed to a thread for execution.

2. Methods and Functionalities

• Thread: The Thread class is equipped with multiple methods such as start(), run(), setName(), getName(), and many more. These methods provide a comprehensive set of functionalities to control and manage the behavior of threads.
• Runnable: Being a functional interface, Runnable has just one abstract method, run(), which contains the code that the thread will execute.

3. Inheritance and Extensibility

• Thread: Scala, being a single inheritance language, doesn't allow a class to inherit from more than one class. Therefore, if you extend the Thread class, you can't extend another class with the same Scala class.
• Runnable: Since Runnable is an interface, you can implement it and still have your class extend another class. This provides greater flexibility in terms of design and structure.

// Example illustrating the limitation of Thread
class MyThread extends Thread, AnotherClass { // This will throw an error
  // Implementation here
}

// Example illustrating the flexibility of Runnable
class MyRunnableTask extends AnotherClass with Runnable {
  // Implementation here
}

Conclusion

In the journey of concurrent programming in Scala, understanding the difference between Thread and Runnable is paramount. While both facilitate multithreading, their inherent characteristics make them suitable for different scenarios. It's essential to choose the right approach based on the specific needs of your application.

• What is the primary difference between Thread and Runnable in Scala?
  • Thread is a class, while Runnable is a functional interface. While both are used for multithreading, they have distinct characteristics and methods.
• Can I extend multiple classes when using Thread in Scala?
  • No, Scala supports single inheritance. If you extend the Thread class, you cannot extend another class with the same Scala class.
• Which approach provides more flexibility in terms of design and structure?
  • Implementing the Runnable interface provides more flexibility as it allows you to implement it and still have your class extend another class.