註冊及反註冊EventBus

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        //註冊
        super.onCreate(savedInstanceState);
        EventBus.getDefault().register(MainActivity.this);
        ...
    }
    ...

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

NOTE: getDefault() 為EventBus內建的Factory method，

也可以建立自定義的EventBus

若沒有EventBus.getDefault().unregister(MainActivity.this); 會造成memory leak