Alternative Expandable View Utilizing Recycler View
An adapter to allow RecyclerView items to expand/collapse properly. Define your parent and corresponding childs and have expand/collapse functionality out of the box.
Add this to the allProjects section in your project-level build.gradle file:
allprojects {
repositories {
...
maven { url 'https://jitpack.io' }
}
}Add this to module level build.gradle file
dependencies {
implementation 'com.github.umutyusuf:expandablerecyclerview:2.0.0'
}Create index provider to indicate positions for parents and childs
class SampleDataIndexProvider(
private val mainStreamGenres: List<MainStreamGenre>,
private val subGenres: Map<MainStreamGenre, List<SubGenre>>
) : ExpandableDataIndexProvider {
override fun getChildrenSize(parentIndex: Int): Int {
return subGenres[mainStreamGenres[parentIndex]]?.size ?: 0
}
override fun getParentSize(): Int {
return mainStreamGenres.size
}
}class MusicExpandableViewAdapter(
private val mainStreamGenres: List<MainStreamGenre>,
private val subGenres: Map<MainStreamGenre, List<SubGenre>>
) : ExpandableViewAdapter(SampleDataIndexProvider(mainStreamGenres, subGenres)) {
override fun createParentViewHolder(container: ViewGroup, viewType: Int): MainStreamViewHolder {
val view = LayoutInflater.from(container.context).inflate(
R.layout.item_main_stream,
container, false
)
return MainStreamViewHolder(view)
}
override fun createChildViewHolder(container: ViewGroup, viewType: Int): SubGenreViewHolder {
val view = LayoutInflater.from(container.context).inflate(
R.layout.item_sub_genre,
container, false
)
return SubGenreViewHolder(view)
}
inner class MainStreamViewHolder(itemView: View) : ParentViewHolder(itemView) {
private val nameTextView: TextView =
itemView.findViewById(R.id.text_view_main_stream_genre_name)
private val expandIndicatorImageView: AppCompatImageView =
itemView.findViewById(R.id.image_view_expand_indicator)
override fun bind(coordinate: Int, state: Int) {
itemView.setOnClickListener { toggle(coordinate) }
nameTextView.text = mainStreamGenres[coordinate].name
setState(state == State.EXPANDED)
}
private fun setState(expand: Boolean) {
if (!expand) {
expandIndicatorImageView.setImageResource(R.drawable.ic_arrow_down)
} else {
expandIndicatorImageView.setImageResource(R.drawable.ic_arrow_up)
}
}
}
inner class SubGenreViewHolder internal constructor(itemView: View) :
ChildViewHolder(itemView) {
private val nameTextView: TextView = itemView.findViewById(R.id.text_view_sub_genre_name)
override fun bind(coordinate: ChildCoordinate) {
nameTextView.text = subGenres[mainStreamGenres[coordinate.parentIndex]]
?.get(coordinate.childRelativeIndex)
?.name ?: ""
}
}
}Finally set adapter to your RecyclerView
val view = findViewById<RecyclerView>(R.id.recycler_view_music_genres)
val adapter = MusicExpandableViewAdapter(
TestData.mainStreamGenres,
TestData.subGenres
)
view.adapter = adapterFor more advanced usage, see demo application.
Copyright 2017 Umut Yusuf Tontus
Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.