How do you display a Toast from a background thread on Android

Question

How can I display Toast messages from a thread

User · Accepted Answer

You can do it by calling an Activity s runOnUiThread method from your thread   activity runOnUiThread new Runnable         public void run             Toast makeText activity   Hello   Toast LENGTH SHORT  show

User · Answer

Sometimes  you have to send message from another Thread to UI thread  This type of scenario occurs when you can t execute Network IO operations on UI thread    Below example handles that scenario    You have UI Thread You have to start IO operation and hence you can t run Runnable on UI thread  So post your Runnable to handler on HandlerThread Get the result from Runnable and send it back to UI thread and show a Toast message    Solution    Create a HandlerThread and start it Create a Handler with Looper from HandlerThread requestHandler Create a Handler with Looper from Main Thread   responseHandler and override handleMessage method post a Runnable task on requestHandler Inside Runnable task  call sendMessage on responseHandler This sendMessage result invocation of handleMessage in responseHandler  Get attributes from the Message and process it  update UI   Sample code          Handler thread         HandlerThread handlerThread   new HandlerThread  HandlerThread        handlerThread start        Handler requestHandler   new Handler handlerThread getLooper          final Handler responseHandler   new Handler Looper getMainLooper               Override         public void handleMessage Message msg                  txtView setText  String  msg obj               Toast makeText MainActivity this                       Runnable on HandlerThread is completed and got result    String msg obj                      Toast LENGTH LONG                       show                          for   int i 0  i lt 5  i              Runnable myRunnable   new Runnable                  Override             public void run                     try                           Add your business logic here and construct the                         Messgae which should be handled in UI thread  For                         example sake  just sending a simple Text here                        String text           rId                       Message msg   new Message                         msg obj   text toString                        responseHandler sendMessage msg                       System out println text toString                        catch  Exception err                        err printStackTrace                                                       requestHandler post myRunnable           Useful articles   handlerthreads-and-why-you-should-be-using-them-in-your-android-apps  android-looper-handler-handlerthread-i

User · Answer

Get UI Thread Handler instance and use handler sendMessage    Call post   method handler post    runOnUiThread   view post

User · Answer

I encountered the same problem   E AndroidRuntime  FATAL EXCEPTION  Thread-4               Process  com example languoguang welcomeapp  PID  4724               java lang RuntimeException  Can t toast on a thread that has not called Looper prepare                     at android widget Toast TN  lt init gt  Toast java 393                    at android widget Toast  lt init gt  Toast java 117                    at android widget Toast makeText Toast java 280                    at android widget Toast makeText Toast java 270                    at com example languoguang welcomeapp MainActivity 1 run MainActivity java 51                    at java lang Thread run Thread java 764  I Process  Sending signal  PID  4724 SIG  9 Application terminated    Before  onCreate function  Thread thread   new Thread new Runnable          Override     public void run             Toast makeText getBaseContext     Thread   Toast LENGTH LONG  show              thread start      After  onCreate function  runOnUiThread new Runnable          Override     public void run             Toast makeText getBaseContext     Thread   Toast LENGTH LONG  show                it worked

User · Answer

Like this or this  with a Runnable that shows the Toast  Namely   Activity activity      reference to an Activity    or View view      reference to a View  activity runOnUiThread new Runnable          Override     public void run             showToast activity                or view post new Runnable          Override     public void run             showToast view getContext                private void showToast Context ctx        Toast makeText ctx   Hi    Toast LENGTH SHORT  show

User · Answer

This is similar to other answers  however updated for new available apis and much cleaner   Also  does not assume you re in an Activity Context   public class MyService extends AnyContextSubclass        public void postToastMessage final String message            Handler handler   new Handler Looper getMainLooper              handler post new Runnable                   Override             public void run                     Toast makeText getContext    message  Toast LENGTH LONG  show

User · Answer

One approach that works from pretty much anywhere  including from places where you don t have an Activity or View  is to grab a Handler to the main thread and show the toast  public void toast final Context context  final String text      Handler handler   new Handler Looper getMainLooper       handler post new Runnable         public void run           Toast makeText context  text  Toast LENGTH LONG  show                   The advantage of this approach is that it works with any Context  including Service and Application

User · Answer

I like to have a method in my activity called showToast which I can call from anywhere     public void showToast final String toast        runOnUiThread    - gt  Toast makeText MyActivity this  toast  Toast LENGTH SHORT  show         I then most frequently call it from within MyActivity on any thread like this     showToast getString R string MyMessage

User · Answer

Kotlin Code with runOnUiThread runOnUiThread          object   Runnable               override fun run                     Toast makeText applicationContext   quot Calling from runOnUiThread   quot   Toast LENGTH SHORT

User · Answer

You can use Looper to send Toast message   Go through this  link for more details    public void showToastInThread final Context context final String str       Looper prepare        MessageQueue queue   Looper myQueue        queue addIdleHandler new IdleHandler              int mReqCount   0             Override          public boolean queueIdle                  if    mReqCount    2                      Looper myLooper   quit                      return false                 else                   return true                         Toast makeText context  str Toast LENGTH LONG  show              Looper loop        and it is called in your thread  Context may be Activity getContext   getting from the Activity you have to show the toast

User · Answer

I made this approach based on mjaggard answer   public static void toastAnywhere final String text        Handler handler   new Handler Looper getMainLooper         handler post new Runnable             public void run                 Toast makeText SuperApplication getInstance   getApplicationContext    text                       Toast LENGTH LONG  show                          Worked well for me

[android] How do you display a Toast from a background thread on Android?

Examples related to android

Examples related to multithreading

Examples related to android-toast