Android: Otto event bus implementation

Question

I'm developing Android app which should use pagination on RecyclerView. I use Executor within Service to make webrequests to API and then persist fetched data in DB. To notify about changes in DB and then apply new data in my adapter I suggest to use Otto event bus. Publisher/subscriber pattern is quite new for me, so I tried to find good tutorial or explanation how this should work but after two days of search I have only foggy idea about what should I implement and how actually Event bus works. Could someone give a good hint where should I start or link on tutorial or code sample? i know that this is a really newbie question but I don't see alternative for this moment.

score 1 · Accepted Answer · answered Aug 10 '16 at 08:44

1

The best guides that I found are: from Vogella and from Codepath. I hope it will help somebody. And good note based on my experience - Otto EventBus works synchronously , keep it in mind.

answered Aug 10 '16 at 08:44

Autumn_Cat

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score -1 · Answer 2 · answered Mar 13 '19 at 09:46

import this library into your app level gradel:

implementation 'org.greenrobot:eventbus:3.0.0'

create a class for Event handling:

public class DataSyncEvent {
    private final String syncStatusMessage;
    private final String countryName;
    private final int postion;

    public DataSyncEvent(String syncStatusMessage, int postion, String countryName) {
        this.syncStatusMessage = syncStatusMessage;
        this.postion = postion;
        this.countryName = countryName;
    }

    public String getSyncStatusMessage() {
        return syncStatusMessage;
    }

    public String countryName() {
        return countryName;
    }

    public int getPostion() {
        return postion;
    }
}

now pass values from your class/fragment or service:

EventBus.getDefault().post(new DataSyncEvent(leftOrRight, position, countryName));

don't forget to register and unregister bus where you are using @Subscribe

@Override
    public void onStart() {
        super.onStart();
        EventBus.getDefault().register(this);
    }
    @Override
    public void onStop() {
        super.onStop();
        EventBus.getDefault().unregister(this);
    }

with @Subscribe you can get that values:

 @Subscribe
    public void onEvent(DataSyncEvent syncStatusMessage) {


        if (syncStatusMessage.getSyncStatusMessage().contains("left")) {

            leftPosition = syncStatusMessage.getPostion();
            img_flag_left.setImageResource(countriesFlag[leftPosition]);
            leftCountryName.setText(syncStatusMessage.countryName());

        } else {
            rightPosition = syncStatusMessage.getPostion();
            img_flag_right.setImageResource(countriesFlag[rightPosition]);
            rightCountryName.setText(syncStatusMessage.countryName());
        }


    }

Android: Otto event bus implementation

2 Answers2