如何保证线程的执行顺序
Posted csong7876
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示例代码
static Thread t1 = new Thread(new Runnable() {
public void run() {
System.out.println("Thread1");
}
});
static Thread t2 = new Thread(new Runnable() {
public void run() {
System.out.println("Thread2");
}
});
static Thread t3 = new Thread(new Runnable() {
public void run() {
System.out.println("Thread3");
}
});
1.使用join
public static void main(String[] args) throws InterruptedException {
t1.start();
t1.join();
t2.start();
t2.join();
t3.start();
}
join源码:
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;
}
}
}
join让主线程等待,至子线程执行结束
2.使用ExecutorService
static ExecutorService es = Executors.newSingleThreadExecutor();
public static void main(String[] args) throws InterruptedException {
es.submit(t1);
es.submit(t2);
es.submit(t3);
es.shutdown();
}
ExecutorService 提供了4种线程池,分别是:
newCachedThreadPool;缓存线程池,可灵活回收、新建
newFixedThreadPool;定长线程池,可控制最大并发数,超出在队列中等待
newScheduledThreadPool;定长线程池,可定时、周期执行
newSingleThreadExecutor;单一线程池,按顺序执行(FIFO,LIFO,优先级)
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