Android处理程序/计时器请求

Question

So I have a question, and if it's a stupid one I do apologize up front, I have tried to search for it but not sure what to search for exactly. I am trying to run a delayed task, but only if my int = 0, would this work correctly like I am wanting it to?

public static void runTask(String p)
{
     Handler handler = new Handler();
        handler.postDelayed(new Runnable() {
            @Override
            public void run()
            {
                pendingRequest = pendingRequest - 1;
                if (pendingRequest == 0)
                {
                        context.startActivity(p);
                }
            }
        }, 4000);
    }

}

What I want it to do is only run if pendingRequest is 0, but I have other activities that add to pending request after the runTask() is called. If this doesn't make any sense please let me know and I will try to reword it.

Answer 1

This is a bit of an obscure way to do things so seeing just this snippet I cant tell exactly what the desired behavior is, however, it should work if you make the parameter "p" final. Im also not familiar with a startActivity method that takes a string instead of an intent, but I cant tell if "context" is actually an Android Context object, but I'm assuming it is. What I'm not sure about is why you would wait 4 seconds BEFORE decrementing pendingRequest. I would think you want to decrement, allow 4 seconds for someone else to add a pending request, and if it's still 0 after the wait start the Activity... but, again, I cant tell from the snippet.

Answer 2

Try this:

private static Object requestLock = new Object();
public static void runTask(final String p)
{
    synchronized(requestLock)
    {
        if (--pendingRequest > 0) // Decrement first
        {
            // There are more requests
            return;
        }
    }

    // Wait 4 sec and if there are still no requests start the activity.
     Handler handler = new Handler();
        handler.postDelayed(new Runnable() {
            @Override
            public void run()
            {
                synchronized(requestLock)
                {
                    if (pendingRequest == 0)
                    {
                        context.startActivity(p);
                    }
                }
            }
        }, 4000);
    }
}

Note: You will also need to add a synchronized block where you increment the pendingRequests.