android UI thread

Question

How can I know if the running code is executed in the main thread (UI thread). With Swing I use the isEventDispatchThread method...

Answer 1

Doesn't look like there is a method for that in the SDK. The check is in the ViewRoot class and is done by comparing Thread.currentThread() to a class member which is assigned in the constructor but never exposed.

If you really need this check you have several options to implement it:

1. catch the android.view.ViewRoot$CalledFromWrongThreadException
2. post a Runnable to a view and check Thread.currentThread()
3. use a Handler to do the same

In general I think instead of checking whether you're on the correct thread, you should just make sure the code is always executed on the UI thread (using 2. or 3.).

Answer 2

Use Looper.getMainLooper().getThread() to get the UI thread.

Answer 3

You may also use runOnUiThread, it only requires a runnable that will be run in the ui thread