创建线程

1. 继承Thread类, 重写run()方法, 调用start()方法启动线程.
   优点: 在run方法内获取当前线程直接使用this就可以了, 无须使用Thread.currentThred()
   缺点: ①Java不支持多继承 ②任务和代码没有分离 ③没有返回值
2. 实现Runnable接口, 具体实现run()方法, 也没有返回值.
3. 实现Callable接口的call()方法, 使用创建的FutureTask对象作为任务创建一个线程并启动它, 最后通过futureTask.get()等待任务执行完毕, 并返回结果.

/**
 * @Description 三种创建线程的方法
 * @Author SYQ
 **/
public class CreateThread {
	public static void main(String[] args) {
		// 继承Thread
		Thread t = new MyThread();
		t.start();

		// 实现Runnable接口
		Runnable r = new RunnableTask();
		new Thread(r).start();
		new Thread(r).start();

		// 实现Callable接口, 可以返回值
		FutureTask<String> futureTask = new FutureTask<>(new CallerTask());
		new Thread(futureTask).start();
		try {
			// 等待任务执行完毕, 并返回结果
			String result = futureTask.get();
			System.out.println(result);
		} catch (InterruptedException e) {
			e.printStackTrace();
			Thread.currentThread().interrupt();
		} catch (ExecutionException e) {
			e.printStackTrace();
		}
	}

	public static class MyThread extends Thread {
		@Override
		public void run() {
			System.out.println("thread1 name: " + this.getName());
			System.out.println("I am a child thread, extends thread");
		}
	}

	public static class RunnableTask implements Runnable {
		@Override
		public void run() {
			System.out.println("thread2 name: " + Thread.currentThread().getName());
			System.out.println("I am a child thread, implements runnable");
		}
	}

	public static class CallerTask implements Callable<String> {
		@Override
		public String call() throws Exception {
			System.out.println("thread3 name: " + Thread.currentThread().getName());
			return "I am a child thread, implements Callable";
		}
	}

}