Java多线程之创建线程的几种方式

线程默认优先级为5，总是main所在的主线程先执行，因为main是程序的入口。

1.继承Thread 重写run 方法

MyThread myThread = new MyThread();
myThread.start();

2.实现Runnable接口  实现run方法

MyRunnable myRunnable = new MyRunnable();
Thread thread = new Thread(myRunnable,"runnable1");
thread.start();

3.实现Callable 接口 实现call方法，然后把 MyCallable 交给Futuretask，然后task 再交给Thread

public class MyCallable implements Callable {
    @Override
    public Integer call() throws Exception {
        int i = 0;
        for (; i <= 10; i++) {
            System.out.println(Thread.currentThread().getName() + "..." + i);
        }
        return i;
    }
}

public class TestCallable {
    public static void main(String[] args) {
        MyCallable myCallable = new MyCallable();
        FutureTask futureTask = new FutureTask<>(myCallable);
        Thread thread = new Thread(futureTask, "callable1");
        thread.start();
        for(int i=0;i<10;i++){
            System.out.println(i + " , main");
        }
    }
}

5.通过线程池创建线程实例

        1. newFixedThreadPool

使用于为了满足资源管理需求而需要限制当前线程数量的场合。使用于负载比较重的服务器。

public static void main(String[] args) {
        ExecutorService fixedThreadPool = Executors.newFixedThreadPool(5);//固定大小的线程池
        for (int j = 0; j < 5; j++) {
            fixedThreadPool.submit(new Runnable() {
                @Override
                public void run() {
                    for (int i = 0; i < 10; i++) {
                        System.out.println(i + " , " +  Thread.currentThread().getName());
                    }
                }
            });
        }
        
        fixedThreadPool.shutdown();
    }

        2.newSingleThreadExecutor 需要保证顺序执行各个任务的场景

public static void main(String[] args) {
        ExecutorService singleThreadPool =  Executors.newSingleThreadExecutor();//单线程池,需要保证顺序执行各个任务的场景
        for (int i = 0; i < 10; i++) {
            singleThreadPool.submit(new Runnable() {
            @Override
            public void run() {
                for (int i = 0; i < 10; i++) {
                    System.out.println(i + " , " +  Thread.currentThread().getName());
                }
            }
            });
        }
        
        
    }

        3. newCachedThreadPool()缓存线程池

当提交任务速度高于线程池中任务处理速度时，缓存线程池会不断的创建线程

适用于提交短期的异步小程序，以及负载较轻的服务器。

public static void main(String[] args) {
        ExecutorService cachedThreadPool = Executors.newCachedThreadPool();//单线程池,需要保证顺序执行各个任务的场景
        for (int i = 0; i < 10; i++) {
            cachedThreadPool.submit(new Runnable() {
            @Override
            public void run() {
                for (int i = 0; i < 10; i++) {
                    System.out.println(i + " , " +  Thread.currentThread().getName());
                }
            }
            });
        }
    }

      还有其他方法创建线程，请大家自行搜索。谢谢大家。