Running code in main thread from another thread

Question

In an android service I have created thread(s) for doing some background task.

I have a situation where a thread needs to post certain task on main thread\'s message

Answer 1

So most handy is to do sort of:

import android.os.AsyncTask
import android.os.Handler
import android.os.Looper

object Dispatch {
    fun asyncOnBackground(call: ()->Unit) {
        AsyncTask.execute {
            call()
        }
    }

    fun asyncOnMain(call: ()->Unit) {
        Handler(Looper.getMainLooper()).post {
            call()
        }
    }
}

And after:

Dispatch.asyncOnBackground {
    val value = ...// super processing
    Dispatch.asyncOnMain { completion(value)}
}

Answer 2

A condensed code block is as follows:

   new Handler(Looper.getMainLooper()).post(new Runnable() {
       @Override
       public void run() {
           // things to do on the main thread
       }
   });

This does not involve passing down the Activity reference or the Application reference.

Kotlin Equivalent:

    Handler(Looper.getMainLooper()).post(Runnable {
        // things to do on the main thread
    })

Answer 3

With Kotlin, it is just like this inside any function:

runOnUiThread {
   // Do work..
}

Answer 4

More precise Kotlin code using handler :

Handler(Looper.getMainLooper()).post {  
 // your codes here run on main Thread
 }

Answer 5

Follow this method. Using this way you can simply update the UI from a background thread. runOnUiThread work on the main(UI) thread . I think this code snippet is less complex and easy, especially for beginners.

AsyncTask.execute(new Runnable() {
            @Override
            public void run() {

            //code you want to run on the background
            someCode();

           //the code you want to run on main thread
 MainActivity.this.runOnUiThread(new Runnable() {

                    public void run() {

/*the code you want to run after the background operation otherwise they will executed earlier and give you an error*/
                        executeAfterOperation();

                   }
                });
            }
        });

in the case of a service

create a handler in the oncreate

 handler = new Handler();

then use it like this

 private void runOnUiThread(Runnable runnable) {
        handler.post(runnable);
    }

Answer 6

public void mainWork() {
    new Handler(Looper.getMainLooper()).post(new Runnable() {
        @Override
        public void run() {
            //Add Your Code Here
        }
    });
}

This can also work in a service class with no issue.