What are the main classes and tools for implementing multithreading in Java?

In Java, the following main classes and tools are used for multithreading:

• Thread — the base class for creating and managing threads. You can create a class that extends Thread or pass a Runnable to the constructor.
• Runnable — a functional interface with the run() method that implements the thread's code.
• Executor and ExecutorService — interfaces and classes from the java.util.concurrent package for managing thread pools and asynchronous task execution.
• Future and Callable — allow running tasks that return a result and can throw exceptions.
• Synchronized, Lock, ReentrantLock — synchronization mechanisms for managing access to shared resources.
• Concurrent Collections (e.g., ConcurrentHashMap) — collections safe for multithreaded access.

Example of creating and starting a thread with Runnable:

public class MyRunnable implements Runnable {
    public void run() {
        System.out.println("Thread is running");
    }
}

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