java多线程调度 java多线程执行顺序问题

        栈中有四个线程：主线程、Thread-0和Thread-1、Thread-2线程。如果有多个线程在排队，那么CPU的执行权是随机抢占的，但是无论哪个线程抢占到CPU的执行权，在线程中都是自上而下执行代码。

代码：

package cx.thread;
public class CreateTherad {
     public static void main(String[] args) {
         Thread thread3 = new Thread(new Runnable() {
             
             @Override
             public void run() {
                 for (int i=0;i<100;i++) {
                     System.out.println(Thread.currentThread().getName()+"-"+i);
                 }
             }
         });
         
         new thread1().start();
         new Thread(new thread2()).start();
         thread3.start();
         for (int i=0;i<100;i++) {
             System.out.println(Thread.currentThread().getName()+"-"+i);
         }
     }}
class thread1 extends Thread {
    @Override
     public void run() {
         for (int i=0;i<100;i++) {
             System.out.println(Thread.currentThread().getName()+"-"+i);
         }
     }
     
 }class thread2 implements Runnable {
    @Override
     public void run() {
         for (int i=0;i<100;i++) {
             System.out.println(Thread.currentThread().getName()+ "-"+i);
         }
     }
     
 }

执行结果：

Thread-1-0
 Thread-1-1
 Thread-1-2
 Thread-1-3
 Thread-1-4
 Thread-1-5
 Thread-1-6
 Thread-1-7
 Thread-1-8
 Thread-1-9
 main-0
 main-1
 main-2
 main-3
 main-4
 main-5
 main-6
 main-7
 main-8
 main-9
 main-10
 main-11
 Thread-2-0
 Thread-1-10
 main-12
 Thread-1-11
 Thread-1-12
 Thread-1-13
 Thread-1-14

那么问题来了，如何控制线程执行的顺序呢？

方法1：使用Thread类提供的join方法，可以达到让线程有序执行的效果。

package cx.thread;
public class TheradJoin {
     public static void main(String[] args) throws InterruptedException {
         Thread thread3 = new Thread(new Runnable() {
             
             @Override
             public void run() {
                 for (int i=0;i<100;i++) {
                     System.out.println(Thread.currentThread().getName()+"-"+i);
                 }
             }
         });
         
         thread11 thread11 = new thread11();
         thread11.start();
         thread11.join();
         
         Thread thread22 = new Thread(new thread22());
         thread22.start();
         thread22.join();
         
         thread3.start();
         thread3.join();
         
         for (int i=0;i<100;i++) {
             System.out.println(Thread.currentThread().getName()+"-"+i);
         }
     }}
class thread11 extends Thread {
    @Override
     public void run() {
         for (int i=0;i<100;i++) {
             System.out.println(Thread.currentThread().getName()+"-"+i);
         }
     }
     
 }class thread22 implements Runnable {
    @Override
     public void run() {
         for (int i=0;i<100;i++) {
             System.out.println(Thread.currentThread().getName()+ "-"+i);
         }
     }
     
 }

方法2：使用线程池

newSingleThreadExecutor 创建一个单线程化的线程池，它只会用唯一的工作线程来执行任务，保证所有任务按照指定顺序(FIFO, LIFO, 优先级)执行。

代码：

package cx.thread;
import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;public class ThreadPool {
     static ExecutorService newSingleThreadExecutor = Executors.newSingleThreadExecutor();
     
     public static void main(String[] args) {
         Thread thread3 = new Thread(new Runnable() {            @Override
             public void run() {
                 for (int i = 200; i < 300; i++) {
                     System.out.println(Thread.currentThread().getName() + "-" + i);
                 }
             }
         });
         
         thread111 thread111 = new thread111();
         
         Thread thread222 = new Thread(new thread222());
         
         newSingleThreadExecutor.execute(thread3);
         newSingleThreadExecutor.execute(thread111);
         newSingleThreadExecutor.execute(thread222);
     }
 }class thread111 extends Thread {
    @Override
     public void run() {
         for (int i=0;i<100;i++) {
             System.out.println(Thread.currentThread().getName()+"-"+i);
         }
     }
     
 }class thread222 implements Runnable {
    @Override
     public void run() {
         for (int i=100;i<200;i++) {
             System.out.println(Thread.currentThread().getName()+ "-"+i);
         }
     }
 }