EventBus can transfer data between Activity Fragment Service threads instead of Intent Broadcast Handler

Related knowledge

Four threadmodes

POSTING: the thread in which the post is published and the event processing function is located

MAIN: event handler runs in UI thread

BACKGROUND: if the event is published in the UI thread, the event handler will run in the new thread. If the event is published in the sub thread, it will run in the published sub thread. The event handler prohibits updating the UI

ASYNC: no matter which thread is published, it will run in the new thread

Registration and cancellation

EventBus.getDefault().register(this) registration

EventBus.getDefault().unregister(this) logout

EventBus.getDefault().isRegister(this) determines whether it is registered true registered false not registered

It's recommended to register to unregister OnCreate before registering with OnDestroy

Sticky event

sticky can send events first and then register

@Subscribe: event subscriber, receiving messages from event publisher

@Publisher: event publisher, directly calling EventBus.getDafault().post(obj)

Ordinary events

public class MainActivity extends AppCompatActivity {

    private AppCompatButton btn_Event;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        btn_Event = findViewById(R.id.btn_event);

        btn_Event.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                startActivity(new Intent(MainActivity.this,SecondActivity.class));
            }
        });
        
        //register
        if (!EventBus.getDefault().isRegistered(this)) {
            EventBus.getDefault().register(this);
        }
    }

    //Event handler
    @Subscribe(threadMode = ThreadMode.MAIN)
    public void onEventFuc(Message message){
        btn_Event.setText(message.getMessage());
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        //Cancellation
        EventBus.getDefault().unregister(this);
    }
}

public class SecondActivity extends AppCompatActivity {

    private AppCompatButton btn_message;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_second);
        btn_message = findViewById(R.id.btn_message);

        btn_message.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //Release events
                EventBus.getDefault().post(new Message("I released the event"));
                finish();
            }
        });
    }
}

Sticky event

public class MainActivity extends AppCompatActivity {

    private AppCompatButton btn_Event, btn_register;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        btn_Event = findViewById(R.id.btn_event);
        btn_register = findViewById(R.id.btn_register);

        btn_Event.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                startActivity(new Intent(MainActivity.this, SecondActivity.class));
            }
        });

        btn_register.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //register
                if (!EventBus.getDefault().isRegistered(this)) {
                    EventBus.getDefault().register(MainActivity.this);
                }
            }
        });


    }

    //Event handler
    @Subscribe(threadMode = ThreadMode.MAIN, sticky = true)
    public void onEventFuc(Message message) {
        btn_Event.setText(message.getMessage());
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        //Cancellation
        EventBus.getDefault().unregister(this);
    }
}

Add more sticky = true to the handler

public class SecondActivity extends AppCompatActivity {

    private AppCompatButton btn_message;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_second);
        btn_message = findViewById(R.id.btn_message);

        btn_message.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //Release events
                EventBus.getDefault().postSticky(new Message("I'm releasing sticky events"));
                finish();
            }
        });
    }
}