How to get back to fragment from nested recycler view child adapter

In this technical blog post, we'll delve into the intricacies of retrieving fragments from within a nested RecyclerView child adapter. Along the way, we'll explore effective coding practices such as view binding and demonstrate how to intercept back-press events in a parent activity.

Working with Nested RecyclerView and Fragments

When working with complex user interfaces, it's often necessary to employ nested RecyclerViews to organize and display data in a structured manner. However, this can introduce challenges when attempting to access fragments from within a child adapter.

To retrieve a fragment from a nested RecyclerView child adapter, follow these steps:

1. Implement View Binding:
   Utilize view binding to streamline the process of finding views within your layout. This reduces the need for冗长findViewById() calls and improves code readability and maintainability.
2. Override the onBindViewHolder() Method:
   Within the onBindViewHolder() method of your child adapter, you can access the fragment associated with the current item.
3. Obtain the Fragment Manager:
   Use the getChildFragmentManager() method to retrieve the fragment manager associated with the child adapter.
4. Find the Fragment by Tag:
   Fragments can be assigned tags to uniquely identify them. Use the findFragmentByTag() method to locate the desired fragment based on its tag.
5. Communicate with the Fragment:
   Once you have a reference to the fragment, you can interact with it by calling its methods or passing data through bundles.

Utilizing View Binding and Collection Iteration

To enhance code readability and simplify complex operations, consider employing view binding and collection iteration. View binding eliminates the need for excessive findViewById() calls, while collection iteration allows you to perform operations on multiple views in a concise and efficient manner.

class MyViewHolder(val binding: ItemBinding) : RecyclerView.ViewHolder(binding.root)

fun onBindViewHolder(...) {
    setTitileText(listOf(holder.title1,holder.title2 ...),listOf(title1,titel2...))
}
fun setTitileText(ar : List<View>,titles :List<String>){
    for (index in 0 until ar.size){
        if(titles.size <= index) continue   
        index = if (title1.length>10) title1.substring(0,10)+"..."else title1
    }
}

Handling Back-Press Events in Parent Activity

To intercept back-press events in a parent activity and perform相应的transactions based on the currently displayed fragment, follow these steps:

1. Add a Callback to the Back Press Dispatcher:
   Within the onCreate() method of your parent activity, add a callback to the back press dispatcher using the onBackPressedDispatcher.
2. Check the Currently Shown Fragment:
   Inside the callback, determine which fragment is currently being displayed by checking its visibility.
3. Perform the Appropriate Transaction:
   Based on the fragment that is being shown, perform the necessary transaction, such as replacing or removing the fragment.

override fun onCreate(...) {
    onBackPressedDispatcher.addCallback(this){
        if(myFragment.isShown) ...
    }
}