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);
}
@Override
public int getItemViewType(int position) {
return mAdapterData.get(position).first;
}
@NonNull
@Override
public 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 last
if (adapterPosition < expandPosition + count) {
break;
}
count += getChildList(expandPosition).size();
//check this
if (adapterPosition <= expandPosition + count) {
return expandPosition;
}
}
// find 绝对位置
return adapterPosition - count;
}
@Override
public 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 = rAdapter
this.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