java java线程和主线程
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java threads and main thread
提问by user121196
what's the best way to make main thread to wait until all threads are finished?
让主线程等待所有线程完成的最佳方法是什么？
for(int i=0;i<n;i++){
Thread t=new Thread();
t.start();
}
//wait for all threads to finish
回答by Peter Lawrey
Create a list and wait for the all.
创建一个列表并等待所有。
List<Thread> threads = new ArrayList<Thread>();
for(int i=0;i<n;i++){
Thread t=new Thread();
t.start();
threads.add(t);
}
for(Thread t: threads) t.join();
However using an ExecutorService can be a more elegant way to handle a pool of threads.
然而，使用 ExecutorService 可以是处理线程池的更优雅的方式。
ExecutorService es = Executors.newCachedThreadPool();
for(int i=0;i<n;i++)
es.submit(new Task(n));
es.shutdown();
es.awaitTermination(timeout, TimeUnit.SECONDS);
回答by Jigar Joshi
List<Thread> threads = new ArrayList<Thread>();
for(int i=0;i<n;i++){
Thread t=new Thread();
threads.add(t);
t.start();
}
for(Thread t:threads){
t.join();
}
回答by sgokhales
It can be done using thread.join( );.
可以使用thread.join( );来完成。
It is also answered here already. Have a look.
这里也已经回答了。看一看。
Example :
例子 ：
class MyThread implements Runnable {
String name; // name of thread
Thread t;
MyThread(String threadname) {
name = threadname;
t = new Thread(this, name);
System.out.println("New thread: " + t);
t.start();
}
public void run() {
try {
for (int i = 5; i > 0; i--) {
System.out.println(name + ": " + i);
Thread.sleep(1000);
}
} catch (InterruptedException e) {
System.out.println(name + " interrupted.");
}
System.out.println(name + " exiting.");
}
}
public class MainClass {
public static void main(String args[]) {
MyThread ob1 = new MyThread("One");
MyThread ob2 = new MyThread("Two");
MyThread ob3 = new MyThread("Three");
System.out.println("Thread One is alive: " + ob1.t.isAlive());
System.out.println("Thread Two is alive: " + ob2.t.isAlive());
System.out.println("Thread Three is alive: " + ob3.t.isAlive());
try {
System.out.println("Waiting for threads to finish.");
ob1.t.join();
ob2.t.join();
ob3.t.join();
} catch (InterruptedException e) {
System.out.println("Main thread Interrupted");
}
System.out.println("Thread One is alive: " + ob1.t.isAlive());
System.out.println("Thread Two is alive: " + ob2.t.isAlive());
System.out.println("Thread Three is alive: " + ob3.t.isAlive());
System.out.println("Main thread exiting.");
}
}
Although the question is tagged under "java", it can be also done in C# in following ways
虽然问题被标记在“java”下，但也可以通过以下方式在 C# 中完成
回答by FatherMathew
You can use a CountDOwnLatch
您可以使用CountDOwnLatch
CountDownLatch lat = new CountDownLatch(noOfTasks);
ExecutorService exec = Executors.newFixedThreadPool(4);
while(...) {
exec.execute(new MyTask());
}
try {
lat.await();
}
catch (InterruptedException E) {
//
}
and within your task (enclose in try / finally)
并在您的任务中（附在 try / finally 中）
lat.countDown();
回答by carmen_munich
I think for your requirement the best solution is the CyclicBarrierlook at http://download.oracle.com/javase/1.5.0/docs/api/java/util/concurrent/CyclicBarrier.html
我认为对于您的要求，最好的解决方案是CyclicBarrier看看http://download.oracle.com/javase/1.5.0/docs/api/java/util/concurrent/CyclicBarrier.html
or
或者
