How can you create and start a thread in Java?

In Java, creating and starting a thread can be done in several ways. The main ones are:

1. Inheritance from the Thread class:

class MyThread extends Thread {
    public void run() {
        System.out.println("Thread started");
    }
}

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

2. Implementing the Runnable interface:

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

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

3. Using lambda expressions (since Java 8):

public class Main {
    public static void main(String[] args) {
        Thread thread = new Thread(() -> {
            System.out.println("Thread started");
        });
        thread.start();
    }
}

The start() method launches a new thread that executes the code in the run() method. It is important not to call run() directly, as that would execute the code in the current thread.