Question

Write a program to implement Runnaable class to create a Thread.

Short answer

Implement a Runnable class, override run(), create a Thread with Runnable, and call start().

Step-by-step solution

Define the Runnable Class

Create a class that implements the Runnable interface. This class must override the run() method, which will contain the code that the thread will execute.

Implement the run() Method

Inside your Runnable class, provide the implementation for the run() method. This is where you add the code you want to execute concurrently. For our example, let's print a simple message.

Create the Runnable Object

Instantiate an object of your class that implements Runnable. This object will act as a task that the thread can execute.

Create a Thread Object

Pass the Runnable object to the constructor of a new Thread object. This step ties the Runnable task to a specific Thread.

Start the Thread

Invoke the start() method on the Thread object. This action will call the run() method in a new thread of execution.

Key concepts

Runnable interface

In Java programming, one of the foundational aspects of creating threads is the Runnable interface. This interface is part of the java.lang package and is most commonly used when you want to define a task that can be executed by a thread. The Runnable interface is purely abstract, meaning it contains just one method: `run()`. This method needs to be overridden in the class that implements the interface and contains the code you wish to execute concurrently.

The simplicity of the Runnable interface allows for cleaner separation of code. Rather than inherently tying your code to the thread's abilities (such as starting or joining), it merely defines what work needs to be performed. This can be beneficial in designing more modularly and maintainable pieces of software, as your Runnable tasks can be passed around to various Thread objects or executed by an executor service.

Thread class

The Thread class in Java is instrumental for any program that deals with concurrent execution. Though you can create threads by extending this class directly, it is often more flexible to implement the Runnable interface and pass an instance of your class to the Thread's constructor. This approach promotes the clear separation of run logic and thread mechanics.

The Thread class provides several methods that are pivotal for thread operation, such as `start()` to begin the thread's life cycle, `sleep()` to pause execution, and `join()` to wait for completion. By using the Thread class in conjunction with the Runnable interface, you can decouple the definition of the task from the threading mechanism itself, thereby promoting reusability and clarity in your code.

concurrent execution

Concurrent execution is a powerful feature in Java, allowing programs to execute multiple tasks simultaneously. This process aims to improve performance by making better use of CPU resources and managing multiple tasks efficiently. In Java, this is most commonly achieved through the Java Concurrency API, which provides robust multithreading support through classes like Thread and interfaces like Runnable.

When you write a Java program with multiple threads, each one can perform different tasks simultaneously or support different parts of the same task. This is especially useful for IO-heavy operations or computational tasks that can be broken down into smaller, parallel units. Properly handling concurrent execution involves not just creating threads but also managing synchronization, ensuring that threads don't interfere with each other and that data is safely shared between them.

run() method implementation

Implementing the `run()` method is one of the critical steps in using the Runnable interface to create threads. This method contains the encapsulated task that the thread will execute once it is started. It's important to remember that calling the `run()` method directly will execute the code in the current thread, instead of starting a new thread. To truly begin concurrent execution, you must pass your Runnable to a Thread object and call `start()` on that Thread, which in turn invokes the `run()` method.

The `run()` method can include any logic your application requires, such as handling data processing, network communication, or performing computations. When creating the `run()` method, it's essential to ensure it's efficient and error-free since it will likely be running alongside other processes. Consideration for exception handling and resource management is also crucial within this method to prevent any unforeseen issues during concurrent execution.