Multithreading and Concurrency Threads and Runnable interface

In Java, multithreading and concurrency are used to execute multiple threads of execution concurrently. A thread is a lightweight process that runs independently of other threads in a program. Here are some basics of threads and the `Runnable` interface in Java:

1. Creating a thread: To create a thread, you can create a class that extends the `Thread` class and overrides the `run` method. For example:

public class MyThread extends Thread {
    @Override
    public void run() {
        // Code to execute in the thread
    }
}

MyThread thread = new MyThread();
thread.start();

Here, a `MyThread` class is created that extends the `Thread` class, and the `run` method is overridden to contain the code to execute in the thread. The thread is then started using the `start` method.

2. The `Runnable` interface: Alternatively, you can create a class that implements the `Runnable` interface and overrides the `run` method. For example:

public class MyRunnable implements Runnable {
    @Override
    public void run() {
        // Code to execute in the thread
    }
}

MyRunnable runnable = new MyRunnable();
Thread thread = new Thread(runnable);
thread.start();

Here, a `MyRunnable` class is created that implements the `Runnable` interface and overrides the `run` method. The `MyRunnable` instance is then passed to a new `Thread` instance, which is started using the `start` method.

3. Joining threads: You can use the `join` method of a thread to wait for the thread to complete before continuing execution. For example:

MyThread thread = new MyThread();
thread.start();
thread.join();

Here, the current thread waits for the `MyThread` instance to complete using the `join` method.

4. Thread synchronization: In a multi-threaded environment, it is important to synchronize access to shared resources to prevent conflicts. You can use the `synchronized` keyword to synchronize access to a block of code or a method. For example:

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

Here, the `increment` method is synchronized, which ensures that only one thread can access it at a time.

The `Thread` class and the `Runnable` interface in Java are powerful tools that allow you to execute multiple threads of execution concurrently. By understanding the basics of threads and the `Runnable` interface, you can write more efficient and effective code that can handle complex tasks and improve performance in your applications.