Android thread Communication

Android uses the UI single-thread model. Therefore, communication between working threads (non-UI threads) and UI threads is inevitable. There are three main ways for a worker thread to communicate with the UI main thread (to update the UI and perform other operations.

First:

Looper. getMainLooper ()

Runnable task = getTask ();

New Handler (Looper. getmainloler (). post (task );

Second:

Activity # runOnUiThread ()

Runnable task = getTask ();

RunOnUiThread (task );

The implements of runOnUiThread is shown as bellow:

Public final void runOnUiThread (Runnable action ){
If (Thread. currentThread ()! = MUiThread ){
MHandler. post (action );
} Else {
Action. run ();
}
}
It will check if the current Thread is already the UI thread and then execute it directly. Posting it as a message will delay the execution until you return from the current UI-thread method.

Third:

There is also a third way to execute a Runnable on the UI thread which wocould be View # post (Runnable)-this one will always post the message even when called from the UI thread. that is useful since that will ensure that the View has been properly constructed and has a layout before the code is executed.