从其他片段更新 recyclerview 适配器

Question

I have a model which is a list of objects and the object contains like_count

The home page has a adapter of the model

onclick of an item traversing to other fragment, if like is clicked in the fragment like count is increased but when user comes back the homepage should reflect the updated like count

also cannot use singleton class as the same model is used on various fragments.

Now I am using broadcast listener but the performance is going slow,

Could anyone please help on this.

Answer 1

Assuming that you are using non-observable data source, the fragment which applies changes should notify caller fragment somehow. You can use setTargetFragment / onActivityResult function pair to return data from called fragment. In this case you can return a boolean flag indicating that there was a change, and caller fragment should check it and reload data if necessary.

Answer 2

I'd strongly suggest checking out Android Jetpack , and in particular the Android ViewModel and LiveData libraries, which let you manage data for an Activity, including across many child fragments. This is likely what @Miha_x64 was referring to with an 'observable data source' - the ViewModel allows you to declare and managed shared data (LiveData) across fragments, and allows those fragments to update the shared data and respond to changes.

Whether or not you decide to go with the ViewModel, there's a really good page of Android documentation that talks about communicating across fragments, I'd suggest starting there: https://developer.android.com/training/basics/fragments/communicating