如何等待所有线程完成

Question

I have this code creating threads. I need to know how to wait for it to finish before launching.

            Map<String, String> accountsToRaidWith = Functions.getAccountsByCrew(accounts, crew);

            for (Map.Entry<String, String> entry : accountsToRaidWith.entrySet()) {
                BossRaiding R1 = new BossRaiding(entry.getKey(), entry.getValue(), raidid);
                R1.start();
            }


            boolean launched = Functions.launchRaid(raidid, id);

class BossRaiding implements Runnable {
    private Thread t;
    String name;
    String id;
    String raidid;

    BossRaiding (String name, String id, String raidid) {
        this.name = name;
        this.id = id;
        this.raidid = raidid;
    }

    public void run() {
        Functions.joinRaid(raidid, id);
    }
    
    public void start () {
        if (t == null) {
            t = new Thread (this);
            t.start ();
        }
    }
}

I am trying to wait for all of the accounts to be joined before it launches. I can't seem to find a method that works correctly.

Answer 1

That Thread t object has a method: join() . This will freeze the thread that executes that method until t stops.

Thus, you could make, in BossRaiding :

public void join() throws InterruptedException {
    t.join();
}

and then just loop through all your instances, calling join() on all of them. If you get through that entire loop, every thread has completed.