static Thread thread1 = new Thread(new Runnable() {
@Override
public void run() {
System.out.println("线程1");
}
});
static Thread thread2 = new Thread(new Runnable() {
@Override
public void run() {
System.out.println("线程2");
}
});
static Thread thread3 = new Thread(new Runnable() {
@Override
public void run() {
System.out.println("线程3");
}
});
执行结果:
正常执行多个线程的话,每个线程的执行顺序都是随机的,这里我们用两种方式来控制一下每个线程的执行顺序。
方式一:
join();
通过join方法保证多线程的顺序性的特性
Join:让主线程等待子线程结束以后才能继续运行。
thread1.start();
thread1.join();
thread2.start();
thread2.join();
thread3.start();
thread3.join();
执行流程图:
以下是join方法源码,这里join()执行的是默认方法,传入millis为0。
public final void join() throws InterruptedException {
join(0);
}
public final synchronized void join(long millis)
throws InterruptedException {
long base = System.currentTimeMillis();
long now = 0;
if (millis < 0) {
throw new IllegalArgumentException("timeout value is negative");
}
if (millis == 0) {
while (isAlive()) {
wait(0);
}
} else {
while (isAlive()) {
long delay = millis - now;
if (delay <= 0) {
break;
}
wait(delay);
now = System.currentTimeMillis() - base;
}
}
}
方式二:
使用java jdk5的一个方法:
ExecutorService executorService = Executors.newSingleThreadExecutor();
executorService.submit(thread1);
executorService.submit(thread2);
executorService.submit(thread3);
executorService.shutdown();