**Course Title:** Comprehensive Java Programming: From Basics to Advanced Concepts **Section Title:** Multithreading and Concurrency in Java **Topic:** Create a multithreaded program to perform parallel tasks and ensure thread safety using synchronization.(Lab topic) **Objective:** By the end of this topic, you will be able to create a multithreaded program in Java that can perform parallel tasks efficiently and ensure thread safety using synchronization techniques. **Multithreading in Java** In the previous topic, we introduced the concept of threads in Java and how they can be used to improve the performance of a program by executing multiple tasks concurrently. However, when multiple threads access shared resources, it can lead to thread interference and memory consistency errors. To prevent these issues, we need to ensure thread safety using synchronization techniques. **Thread Safety and Synchronization** Thread safety refers to the ability of a program to function correctly even when multiple threads are accessing shared resources. Synchronization is the process of coordinating access to shared resources by multiple threads to prevent thread interference and memory consistency errors. In Java, we can use the following synchronization techniques to ensure thread safety: 1. **Synchronized methods**: We can declare methods as synchronized, which means only one thread can execute the method at a time. 2. **Synchronized blocks**: We can use synchronized blocks to synchronize access to a specific block of code within a method. 3. **Locks**: We can use locks to synchronize access to a shared resource. **Creating a Multithreaded Program** To create a multithreaded program in Java, we need to follow these steps: 1. **Create a class that extends the Thread class**: We can create a class that extends the Thread class and override the run() method to define the task that we want to execute concurrently. 2. **Create instances of the Thread class**: We can create multiple instances of the Thread class to execute multiple tasks concurrently. 3. **Start the threads**: We can start the threads using the start() method. **Example: Creating a Multithreaded Program** Here is an example of a multithreaded program that performs two tasks concurrently: ```java class Task1 extends Thread { public void run() { for (int i = 0; i < 10; i++) { System.out.println("Task 1: " + i); try { Thread.sleep(100); } catch (InterruptedException e) { Thread.currentThread().interrupt(); } } } } class Task2 extends Thread { public void run() { for (int i = 0; i < 10; i++) { System.out.println("Task 2: " + i); try { Thread.sleep(100); } catch (InterruptedException e) { Thread.currentThread().interrupt(); } } } } public class MultithreadedProgram { public static void main(String[] args) { Task1 task1 = new Task1(); Task2 task2 = new Task2(); task1.start(); task2.start(); } } ``` **Ensuring Thread Safety** To ensure thread safety, we need to synchronize access to shared resources. Here is an example of how we can synchronize access to a shared resource using a synchronized method: ```java class Counter { private int count = 0; public synchronized void increment() { count++; } public synchronized int getCount() { return count; } } ``` In this example, we have a Counter class that has two synchronized methods: increment() and getCount(). The increment() method increments the count variable, and the getCount() method returns the current count. **Conclusion** In this topic, we learned how to create a multithreaded program in Java that can perform parallel tasks efficiently. We also learned how to ensure thread safety using synchronization techniques such as synchronized methods, synchronized blocks, and locks. By following the steps outlined in this topic, you can create your own multithreaded programs that can execute multiple tasks concurrently and ensure thread safety. **Additional Resources** For more information on multithreading and concurrency in Java, you can refer to the following resources: * Oracle's Java Tutorials: [https://docs.oracle.com/javase/tutorial/essential/concurrency/index.html](https://docs.oracle.com/javase/tutorial/essential/concurrency/index.html) * Java API Documentation: [https://docs.oracle.com/javase/8/docs/api/java/lang/Thread.html](https://docs.oracle.com/javase/8/docs/api/java/lang/Thread.html) **Questions and Comments** If you have any questions or comments regarding this topic, please leave a comment below.