Chapter 10: Multithreading and Concurrency

Introduction:

Multithreading and concurrency allow you to execute multiple tasks concurrently, making your Java programs more efficient and responsive. In this chapter, we will explore multithreading, synchronization, and concurrency in Java.

Introduction to Multithreading:

Multithreading is the execution of multiple threads concurrently within a single program. Threads are independent units of execution that allow you to perform multiple tasks simultaneously.

Example:

java

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class MyThread extends Thread {

    public void run() {

        // Code to be executed in the thread

    }

}

// Create and start a thread

MyThread thread = new MyThread();

thread.start();

Thread Synchronization:

Thread synchronization is the coordination of multiple threads to ensure proper and predictable execution. It prevents multiple threads from accessing shared resources simultaneously, avoiding race conditions and data inconsistencies.

Example using synchronized method:

java

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class Counter {

    private int count = 0;

    public synchronized void increment() {

        count++;

    }

}

Counter counter = new Counter();

Thread Communication:

Thread communication allows threads to communicate and synchronize their actions. It involves techniques such as wait(), notify(), and notifyAll() to coordinate the execution flow of threads.

Example using wait() and notify():

java

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class Message {

    private String content;

    private boolean empty = true;

    public synchronized String read() {

        while (empty) {

            try {

                wait();

            } catch (InterruptedException e) {

                e.printStackTrace();

            }

        }

        empty = true;

        notifyAll();

        return content;

    }

    public synchronized void write(String message) {

        while (!empty) {

            try {

                wait();

            } catch (InterruptedException e) {

                e.printStackTrace();

            }

        }

        empty = false;

        content = message;

        notifyAll();

    }

}

Message message = new Message();

Thread Pool and Executors:

A thread pool is a collection of worker threads that are managed by an executor. It provides a convenient way to reuse threads and efficiently manage concurrent tasks.

Example using ExecutorService:

java

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ExecutorService executor = Executors.newFixedThreadPool(5);

executor.submit(() -> {

    // Code to be executed by the thread

});

executor.shutdown();

Concurrent Collections:

Java provides concurrent collections that are designed to be thread-safe and efficient for concurrent access. These collections include ConcurrentHashMap, ConcurrentLinkedQueue, and ConcurrentSkipListSet.

Example using ConcurrentHashMap:

java

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ConcurrentMap<String, Integer> scores = new ConcurrentHashMap<>();

scores.put("John", 90);

scores.put("Emily", 95);

scores.put("Peter", 85);

int score = scores.get("Emily");

Conclusion:

In this chapter, we explored multithreading and concurrency in Java. We discussed multithreading basics, thread synchronization, thread communication, thread pools, and concurrent collections. Multithreading and concurrency are powerful tools for improving the performance and responsiveness of your Java programs, enabling efficient execution of concurrent tasks.

Note: Make sure to include additional chapters and topics to cover all the essential aspects of Java programming in your book. The provided content is a sample for Chapter 10 only.