Question

The android Handler class contains this method:

public final boolean postAtTime (Runnable r, Object token, long uptimeMillis)

to post a Runnable at a given time. The token can be used later to remove the callback to r from the message queue thanks to this method:

public final void removeCallbacks (Runnable r, Object token)

The following method doesn’t exist in the Handler class

public final boolean postDelayed (Runnable r, Object token, long delay)

Is there a good reason for not providing such a method?

Answer 1

After looking at the source code, the token object eventually passes to the Message:

public final boolean postAtTime(Runnable r, Object token, long uptimeMillis)
308    {
309        return sendMessageAtTime(getPostMessage(r, token), uptimeMillis);
310    }

private static Message getPostMessage(Runnable r, Object token) {
608        Message m = Message.obtain();
609        m.obj = token;

And postDelay

 public final boolean postDelayed(Runnable r, long delayMillis)
330    {
331        return sendMessageDelayed(getPostMessage(r), delayMillis);
332    }

If what you want is

public final boolean postDelayed (Runnable r, Object token, long delay)

Then why not just use

public final boolean postAtTime (Runnable r, Object token, long uptimeMillis)

since its the same.

Update, forgot to add this:

public final boolean sendMessageDelayed(Message msg, long delayMillis)
442    {
443        if (delayMillis < 0) {
444            delayMillis = 0;
445        }
446        return sendMessageAtTime(msg, SystemClock.uptimeMillis() + delayMillis);
447    }