How to detect UI thread on Android?
Is there a robust way to detect if Thread.currentThread()
is the Android system UI thread in an a开发者_运维百科pplication?
Common practice to determine the UI Thread's identity is via Looper#getMainLooper:
if (Looper.getMainLooper().getThread() == Thread.currentThread()) {
// On UI thread.
} else {
// Not on UI thread.
}
From API level 23 and up, there's a slightly more readable approach using new helper method isCurrentThread on the main looper:
if (Looper.getMainLooper().isCurrentThread()) {
// On UI thread.
} else {
// Not on UI thread.
}
I think that best way is this:
if (Looper.getMainLooper().equals(Looper.myLooper())) {
// UI thread
} else {
// Non UI thread
}
As of API level 23 the Looper
has a nice helper method isCurrentThread
. You could get the mainLooper
and see if it's the one for the current thread this way:
Looper.getMainLooper().isCurrentThread()
It's practically the same as:
Looper.getMainLooper().getThread() == Thread.currentThread()
but it could be a bit more readable and easier to remember.
public boolean onUIThread() {
return Looper.getMainLooper().isCurrentThread();
}
But it requires API level 23
Besides checking looper, if you ever tried to logout thread id in onCreate()
, you could find the UI thread(main thread) id always equals to 1. Therefore
if (Thread.currentThread().getId() == 1) {
// UI thread
}
else {
// other thread
}
Nice extension for Kotlin:
val Thread.isMain get() = Looper.getMainLooper().thread == Thread.currentThread()
So you just call:
Thread.currentThread().isMain
Couldn't you use the runOnUiThread
method in the Activity
class?See..
http://developer.android.com/reference/android/app/Activity.html#runOnUiThread%28java.lang.Runnable%29
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