【Android】RV折叠适配器

1，折叠List，除了使用ListView中已有的ExpandAdapter，笔者定制化了此类，用户折叠列表的RV通用实现，仅供参考。

BaseExpandRecyclerAdapter，

​import android.annotation.SuppressLint;
import android.util.Pair;
import android.view.ViewGroup;import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.stream.Collectors;public abstract class BaseExpandRecyclerAdapter<Parent, Child> extends RecyclerView.Adapter<RecyclerView.ViewHolder> {protected static final int PARENT_TYPE = "BaseExpandRecyclerAdapter".hashCode() + 1;protected static final int CHILD_TYPE = "BaseExpandRecyclerAdapter".hashCode() + 2;private final List<Pair<Parent, List<Child>>> mData = new ArrayList<>();private final List<Pair<Integer, Object>> mAdapterData = new ArrayList<>();private final List<Integer> mExpandParentPositionList = new ArrayList<>();public BaseExpandRecyclerAdapter() {}@SuppressLint("NotifyDataSetChanged")public void notifyData(List<Pair<Parent, List<Child>>> data) {mData.clear();mData.addAll(data);notifyAdapterDataSourcesChange();notifyDataSetChanged();}private void notifyAdapterDataSourcesChange() {mAdapterData.clear();if (mExpandParentPositionList.isEmpty()) {mAdapterData.addAll(mData.stream().map(it -> Pair.create(getItemViewTypeFromObject(it.first, PARENT_TYPE), (Object) it.first)).collect(Collectors.toList()));return;}for (int i = 0; i < mData.size(); i++) {mAdapterData.add(Pair.create(PARENT_TYPE, getParentData(i)));if (mExpandParentPositionList.contains(i)) {List<Child> childList = getChildList(i);mAdapterData.addAll(childList.stream().map(it -> Pair.create(getItemViewTypeFromObject(it, CHILD_TYPE), (Object) it)).collect(Collectors.toList()));}}}private int notifyAdapterDataSourcesInsert(int newExpandPosition) {int insertStart = getAdapterPosition(newExpandPosition) + 1;mAdapterData.addAll(insertStart, getChildList(newExpandPosition).stream().map(it -> Pair.create(getItemViewTypeFromObject(it, CHILD_TYPE), (Object) it)).collect(Collectors.toList()));return insertStart;}private int notifyAdapterDataSourcesRemove(int oldExpandPosition) {int removeStart = getAdapterPosition(oldExpandPosition) + 1;int count = getChildList(oldExpandPosition).size();Iterator<Pair<Integer, Object>> iterator = mAdapterData.iterator();int i = 0;while (iterator.hasNext()) {iterator.next();if (i >= removeStart && i < removeStart + count) {iterator.remove();}i++;if (i >= removeStart + count) {break;}}return removeStart;}protected int getAdapterPosition(int parentPosition) {if (mExpandParentPositionList.isEmpty()) {return parentPosition;}int count = mExpandParentPositionList.stream().filter(it -> parentPosition > it).mapToInt(it -> getChildList(it).size()).sum();return parentPosition + count;}/*** 展开*/public void notifyExpand(int parentPosition) {boolean nextExpandStatus = !isExpand(parentPosition);notifyExpand(parentPosition, nextExpandStatus);}public void notifyExpand(int parentPosition, boolean expand) {if (!onSupportParentExpand(parentPosition, expand)) {return;}int index = mExpandParentPositionList.indexOf(parentPosition);int size = getChildList(parentPosition).size();if (index >= 0) {if (expand) {return;}mExpandParentPositionList.remove(index);int removeStart = notifyAdapterDataSourcesRemove(parentPosition);notifyItemRangeRemoved(removeStart, size);notifyItemRangeChanged(removeStart, mAdapterData.size() - removeStart);} else {if (!expand) {return;}mExpandParentPositionList.add(parentPosition);int insertStart = notifyAdapterDataSourcesInsert(parentPosition);notifyItemRangeInserted(insertStart, size);notifyItemRangeChanged(insertStart, mAdapterData.size() - insertStart);}}public boolean isExpand(int parentPosition) {return mExpandParentPositionList.contains(parentPosition);}public List<Pair<Parent, List<Child>>> getData() {return mData;}public List<Pair<Integer, Object>> getAdapterData() {return mAdapterData;}public Parent getParentData(int parentPosition) {return mData.get(parentPosition).first;}public Child getChildData(int parentPosition, int childPosition) {return mData.get(parentPosition).second.get(childPosition);}@Overridepublic int getItemViewType(int position) {return mAdapterData.get(position).first;}@NonNull@Overridepublic RecyclerView.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {if (viewType == PARENT_TYPE) {return onParentViewHolder(parent);}if (viewType == CHILD_TYPE) {return onChildViewHolder(parent);}return onCreateCommonViewHolder(parent, viewType);}@Override@SuppressWarnings("unchecked")public void onBindViewHolder(@NonNull RecyclerView.ViewHolder holder, int position) {Pair<Integer, Object> data = mAdapterData.get(position);int type = data.first;if (type == PARENT_TYPE) {holder.itemView.setOnClickListener(v -> {int parentPosition = getParentPosition(position);notifyExpand(parentPosition);onParentClick(holder, parentPosition);});onBindParentViewHolder(holder, (Parent) data.second);} else if (type == CHILD_TYPE) {holder.itemView.setOnClickListener(v -> {int parentPosition = getParentPosition(position);onChildClick(holder, parentPosition, position - getAdapterPosition(parentPosition) - 1);});onBindChildViewHolder(holder, (Child) data.second);} else {onBindCommonViewHolder(holder, position, data.second);}}private List<Child> getChildList(int parentPosition) {return mData.get(parentPosition).second;}protected int getParentPosition(int adapterPosition) {if (mExpandParentPositionList.isEmpty()) {return adapterPosition;}List<Integer> validExpandPosition = mExpandParentPositionList.stream().filter(it -> it < adapterPosition).sorted().collect(Collectors.toList());if (validExpandPosition.isEmpty()) {return adapterPosition;}int count = 0;for (int expandPosition : validExpandPosition) {//check lastif (adapterPosition < expandPosition + count) {break;}count += getChildList(expandPosition).size();//check thisif (adapterPosition <= expandPosition + count) {return expandPosition;}}// find 绝对位置return adapterPosition - count;}@Overridepublic int getItemCount() {return mAdapterData.size();}protected abstract RecyclerView.ViewHolder onParentViewHolder(ViewGroup parent);protected abstract RecyclerView.ViewHolder onChildViewHolder(ViewGroup parent);/*** 存在其他类型的viewHolder时，需要重写的方法，** @see #getItemViewType(int)*/protected RecyclerView.ViewHolder onCreateCommonViewHolder(ViewGroup parent, int viewType) {throw new IllegalArgumentException("unSupport type " + viewType);}protected void onBindCommonViewHolder(RecyclerView.ViewHolder holder, int position, Object data) {throw new IllegalArgumentException("unSupport  CommonViewHolder " + holder);}/*** 根据object返回自定义Type** @param object:数据* @param defaultType :默认类型{@link #CHILD_TYPE} {@link #PARENT_TYPE}*/protected int getItemViewTypeFromObject(Object object, int defaultType) {return defaultType;}protected abstract void onBindChildViewHolder(RecyclerView.ViewHolder holder, Child data);protected abstract void onBindParentViewHolder(RecyclerView.ViewHolder holder, Parent data);/*** 是否支持parentPosition的下一个展开状态** @param parentPosition   目标位置* @param nextExpandStatus 下一个展开状态*/protected abstract boolean onSupportParentExpand(int parentPosition, boolean nextExpandStatus);protected void onParentClick(RecyclerView.ViewHolder holder, int parentPosition) {}protected void onChildClick(RecyclerView.ViewHolder holder, int parentPosition, int childPosition) {}
}​

实例如下

class ExpandListFragment : BaseComposeFragment() {private val rAdapter = RAdapter()override fun onContentView(rootView: ComposeView) {rootView.apply {doOnAttach {rAdapter.notifyData(listOf(Pair(Parent(1), listOf(Child(2, 1))),Pair(Parent(2), listOf(Child(2, 2), Child(3, 2), Child(4, 2),)),Pair(Parent(3), listOf(Child(3, 3), Child(3, 3), Child(4, 3),)),Pair(Parent(3), listOf(Child(3, 4), Child(3, 4), Child(4, 4),)),Pair(Parent(3), listOf(Child(3, 4), Child(3, 4), Child(4, 4),)),Pair(Parent(3), listOf(Child(3, 4), Child(3, 4), Child(4, 4),)),Pair(Parent(3), listOf(Child(3, 4), Child(3, 4), Child(4, 4),)),Pair(Parent(3), listOf(Child(3, 4), Child(3, 4), Child(4, 4),)),Pair(Parent(3), listOf(Child(3, 4), Child(3, 4), Child(4, 4),)),Pair(Parent(3), listOf(Child(3, 4), Child(3, 4), Child(4, 4),)),))"notify data".shortToast()}}.setContent {MyApplicationTheme {Surface(modifier = Modifier.fillMaxSize()) {AndroidView(factory = {RecyclerView(it).apply {this.adapter = rAdapterthis.layoutManager = LinearLayoutManager(it)}}, modifier = Modifier.fillMaxSize())}}}}override fun onSubscribeValue() {}private class RAdapter : BaseExpandRecyclerAdapter<Parent, Child>() {override fun onChildClick(holder: RecyclerView.ViewHolder, parentPosition: Int, childPosition: Int) {"click $parentPosition $childPosition ".shortToast()}override fun onParentClick(holder: RecyclerView.ViewHolder, parentPosition: Int) {"click $parentPosition ".shortToast()}override fun onBindChildViewHolder(holder: RecyclerView.ViewHolder, data: Child?) {data?.let {(holder.itemView as TextView).text = "parentId${data.parentId} selfId:${data.id} ${holder.javaClass.simpleName}"}}override fun onBindParentViewHolder(holder: RecyclerView.ViewHolder, data: Parent?) {data?.let {(holder.itemView as TextView).text = "selfId:${data.id} ${holder.javaClass.simpleName}"}}override fun onSupportParentExpand(parentPosition: Int, nextExpandStatus: Boolean): Boolean {return true}override fun onParentViewHolder(parent: ViewGroup): RecyclerView.ViewHolder {return ParentViewHolder(TextView(parent.context))}override fun onChildViewHolder(parent: ViewGroup): RecyclerView.ViewHolder {return ChildViewHolder(TextView(parent.context))}}}data class Parent(val id: Int)
data class Child(val id: Int, val parentId: Int)class ParentViewHolder(val view: View) : RecyclerView.ViewHolder(view)
class ChildViewHolder(val view: View) : RecyclerView.ViewHolder(view)

效果如下：

可折叠列表