Java构建线程的方式

1. 继承Thread类

通过创建一个继承自Thread类的子类，然后覆盖run()方法来定义线程的执行逻辑。

class MyThread extends Thread {public void run() {// 线程执行的代码System.out.println("Thread is running");}
}public class Main {public static void main(String[] args) {MyThread myThread = new MyThread();myThread.start(); // 启动线程}
}

2. 实现Runnable接口

通过创建一个实现Runnable接口的类，然后将该类的实例传递给Thread类的构造函数。

class MyRunnable implements Runnable {public void run() {// 线程执行的代码System.out.println("Runnable is running");}
}public class Main {public static void main(String[] args) {MyRunnable myRunnable = new MyRunnable();Thread thread = new Thread(myRunnable);thread.start(); // 启动线程}
}

3.实现Callable

import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;
import java.util.concurrent.FutureTask;class MyCallable implements Callable<String> {public String call() throws Exception {// 线程执行的代码，并返回一个结果return "Callable is running";}
}public class Main {public static void main(String[] args) {// 创建一个Callable任务Callable<String> callable = new MyCallable();// 将Callable任务封装成一个FutureTaskFutureTask<String> futureTask = new FutureTask<>(callable);// 将FutureTask传递给Thread构造函数创建线程Thread thread = new Thread(futureTask);thread.start(); // 启动线程try {// 获取线程执行结果String result = futureTask.get();System.out.println(result);} catch (InterruptedException | ExecutionException e) {e.printStackTrace();}}
}

4.线程池

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;public class ThreadPoolExample {public static void main(String[] args) {// 创建一个固定大小的线程池，大小为3ExecutorService executorService = Executors.newFixedThreadPool(3);// 提交任务给线程池for (int i = 1; i <= 5; i++) {final int taskId = i;executorService.submit(() -> {System.out.println("Task " + taskId + " is running on thread " + Thread.currentThread().getName());});}// 关闭线程池executorService.shutdown();}
}

在这个例子中，通过Executors.newFixedThreadPool(3)创建一个包含3个线程的固定大小线程池。然后通过executorService.submit()方法提交任务给线程池执行。最后，调用executorService.shutdown()来关闭线程池。

线程池的好处包括：