Cool things I learned, Part 1 - Base Fragments and Containers

Say you want a generic design in all your Fragments but hate doing it again and again every time you create a new Fragment.

Enter abstract fragments with containers.

Step 1. Create a Base Fragment

abstract class BaseFragment(
  private val contentResId: Int = 0
) : Fragment() {

  override fun onCreateView(
    inflater: LayoutInflater,
    container: ViewGroup?,
    savedInstanceState: Bundle?
  ): View? {
    super.onCreateView(inflater, container, savedInstanceState)
    return inflater.inflate(R.layout.base_container, container, false).also {
      val containerContent = it!!.findViewById<FrameLayout>(R.id.container_content)
      containerContent.addView(
        onCreateContentView(inflater, containerContent, savedInstanceState)
      )
    }
  }

  open fun onCreateContentView(
    inflater: LayoutInflater,
    onboardingContainer: FrameLayout,
    savedInstanceState: Bundle?
  ): View {
    return inflater.inflate(contentResId, onboardingContainer, false)
  }
}

The interesting part over here is inflating the container and adding the it to the base layout.

This is how the XML would look like

<?xml version="1.0" encoding="utf-8"?>
<ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:clipChildren="false"
    android:clipToPadding="false"
    android:fitsSystemWindows="false">

    <FrameLayout
        android:id="@+id/container_content"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

</ConstraintLayout>

Step 2.

Create a new Fragment and extend from the above base fragment

class DoSomethingFragment(): BaseFragment(R.layout.do_something_xml)

And that's it. You get all the benefits of the BaseFragment, its design, elements, etc and you get the features of the implementing fragment as well. Pretty cool!