How to make a toast in an onfailure method

Question

I use OkHttp in a separate service to fetch data from the twitter API. I have been trying to Alert the user that tweets cannot be loaded without an internet connection. But when i try this, the application crashes.The error is java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare(). Here's my code

 private void getTweets(final String topic) {
    final TwitterService twitterService = new TwitterService();
    twitterService.findTweets(topic, new Callback() {
        @Override
        public void onFailure(Request request, IOException e) {
            e.printStackTrace();
            Log.e("Traffic Activity", "Failed to make API call");
            Toast.makeText(getApplicationContext(), "Bigger fail", Toast.LENGTH_LONG).show();

        }

score 2 · Accepted Answer · answered Aug 20 '17 at 07:30

Probably you are calling Toast.makeText from the wrong thread. It needs to be called from the UI thread. Try this instead

activity.runOnUiThread(new Runnable() {
    public void run() {
        Toast.makeText(activity, msg, Toast.LENGTH_SHORT).show();
    }
});

More informations here Can't create handler inside thread that has not called Looper.prepare()

score 1 · Answer 2 · answered Aug 20 '17 at 07:35

You're calling it from a worker thread. You need to call Toast.makeText() (and most other functions dealing with the UI) from within the main thread. You could use a handler, for example

//set this up in UI thread

mHandler = new Handler(Looper.getMainLooper()) {
@Override
public void handleMessage(Message message) {
    // This is where you do your work in the UI thread.
    // Your worker tells you in the message what to do.
}

};

void workerThread() {
// And this is how you call it from the worker thread:
Message message = mHandler.obtainMessage(command, parameter);
message.sendToTarget();

}

How to make a toast in an onfailure method

2 Answers2