创建线程的几种方式

1、继承Thread类、创建一个类、继承Thread类、并重写run()方法来定义线程执行的逻辑、然后实例化这个类并调用start方法启动线程。

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

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

2、实现Runnable接口、创建一个类、实现Runnable接口并实现run方法、然后将该Runnable实例传递给Thread类的构造方法、最后调用start方法启动线程。

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

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

3、使用匿名内部类、通过匿名内部类来实现Runnable接口的run方法、直接在Thread类的构造方法中创建并传递。

    public static void main(String[] args) {
        Thread thread = new Thread(new Runnable() {
            public void run() {
                System.out.println("Thread using anonymous inner class is running");
            }
        });
        
        thread.start();
    }
}

4、使用lambda表达式、使用lambda表达式代替匿名类部类来实现Runnable接口的run方法。

public class ThreadExample {
    public static void main(String[] args) {
        Thread thread = new Thread(() -> {
            System.out.println("Thread using Lambda expression is running");
        });

        thread.start();
    }
}

5、使用callable和future接口、callable接口类似于runnable接口、但它可以返回并抛出受检异常、可以使用callable接口和future接口来创建线程并获取线程执行的结果

import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.FutureTask;

public class ThreadExample {
    public static void main(String[] args) {
        Callable<String> callable = () -> {
            return "Thread using Callable interface is running";
        };

        FutureTask<String> futureTask = new FutureTask<>(callable);
        Thread thread = new Thread(futureTask);
        thread.start();

        try {
            System.out.println(futureTask.get());
        } catch (InterruptedException | ExecutionException e) {
            e.printStackTrace();
        }
    }
}

6、使用线程池、通过java中的ExecutorService和相关类可以创建线程池、然后将任务提交给线程池执行、以便重复利用线程并控制并发度。

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

public class ThreadExample {
    public static void main(String[] args) {
        ExecutorService executor = Executors.newFixedThreadPool(2);

        executor.submit(() -> {
            System.out.println("Thread in thread pool is running");
        });

        executor.shutdown();
    }
}