Java Multithreading

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Multithreading is an essential technique for creating more efficient and responsive programs. In Java, it's relatively simple to implement and can make a world of difference in your applications. Let's dive into the exciting world of Java multithreading!

What is Multithreading?

Multithreading is a form of parallelism in which several independent threads of execution can be run concurrently. This enables your program to perform multiple tasks simultaneously, making it faster and more responsive. In Java, multithreading is supported by the Thread class and the Runnable interface.

Creating Threads in Java

There are two primary ways to create a new thread in Java: extending the Thread class or implementing the Runnable interface. Let's take a look at both approaches.

Extending the Thread Class

To create a new thread by extending the Thread class, you simply need to create a new class that extends Thread and override the run() method. The run() method contains the logic that will be executed in the new thread. Here's an example:

class MyThread extends Thread {
    public void run() {
        // Your thread logic here
        System.out.println("Hello from MyThread!");
    }
}

public class Main {
    public static void main(String[] args) {
        MyThread myThread = new MyThread();
        myThread.start(); // Start the new thread
    }
}

Implementing the Runnable Interface

Alternatively, you can create a new thread by implementing the Runnable interface, which requires you to implement the run() method. Then, you'll need to pass an instance of your Runnable class to a new Thread object. Here's an example:

class MyRunnable implements Runnable {
    public void run() {
        // Your thread logic here
        System.out.println("Hello from MyRunnable!");
    }
}

public class Main {
    public static void main(String[] args) {
        MyRunnable myRunnable = new MyRunnable();
        Thread thread = new Thread(myRunnable);
        thread.start(); // Start the new thread
    }
}

Both approaches are valid, but implementing the Runnable interface is generally preferred, as it allows your class to extend another class if needed since Java does not support multiple inheritance.

Synchronization and Thread Safety

When multiple threads access shared resources, there's a risk of data inconsistency or race conditions. To ensure data integrity, it's essential to use synchronization techniques. In Java, you can use the synchronized keyword to achieve this:

class Counter {
    private int count = 0;

    public synchronized void increment() {
        count++;
    }

    public synchronized int getCount() {
        return count;
    }
}

class MyRunnable implements Runnable {
    private Counter counter;

    public MyRunnable(Counter counter) {
        this.counter = counter;
    }

    public void run() {
        counter.increment();
    }
}

public class Main {
    public static void main(String[] args) throws InterruptedException {
        Counter counter = new Counter();
        Thread[] threads = new Thread[10];

        // Start multiple threads
        for (int i = 0; i < threads.length; i++) {
            threads[i] = new Thread(new MyRunnable(counter));
            threads[i].start();
        }

        // Wait for all threads to finish
        for (Thread thread : threads) {
            thread.join();
        }

        System.out.println("Final count: " + counter.getCount());
    }
}

In this example, the synchronized keyword ensures that only one thread can access the increment() and getCount() methods at a time, preventing race conditions and ensuring data consistency.

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