java多线程启动的四种方式

继承Thread类：创建一个类继承Thread类，并重写run()方法，然后创建该类的实例并调用start()方法来启动线程。

public class MyThread extends Thread {
    @Override
    public void run() {
        // 线程执行的代码逻辑
    }
}

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

实现Runnable接口：创建一个类实现Runnable接口，并实现其run()方法，然后创建Thread的实例，将实现了Runnable接口的类的实例作为参数传递给Thread的构造函数，最后调用start()方法来启动线程。

public class MyRunnable implements Runnable {
    @Override
    public void run() {
        // 线程执行的代码逻辑
    }
}

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

使用Callable和Future：创建一个类实现Callable接口，并实现其call()方法，然后使用ExecutorService的submit()方法将实现了Callable接口的类的实例提交给线程池执行。

import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;

public class MyCallable implements Callable<String> {
    @Override
    public String call() throws Exception {
        // 线程执行的代码逻辑
        return "Hello, World!";
    }
}

public class Main {
    public static void main(String[] args) {
        ExecutorService executorService = Executors.newFixedThreadPool(1);
        Future<String> future = executorService.submit(new MyCallable());
        try {
            String result = future.get();
            System.out.println(result);
        } catch (Exception e) {
            e.printStackTrace();
        }
        executorService.shutdown();
    }
}

使用线程池：通过Executors类的静态方法创建一个线程池，然后将实现了Runnable接口或Callable接口的实例通过submit()方法提交给线程池执行。

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class MyRunnable implements Runnable {
    @Override
    public void run() {
        // 线程执行的代码逻辑
    }
}

public class Main {
    public static void main(String[] args) {
        ExecutorService executorService = Executors.newFixedThreadPool(1);
        executorService.submit(new MyRunnable());
        executorService.shutdown();
    }
}
``