我正在使用此library制作可扩展的RecyclerView 我制作了自己的版本，所以我可以定义标题，但它给了我，我认为我做错了，因为它给了我this错误。
我想要的是：
我的ExpandableRecyclerView版本：
public class ExpandableRecyclerView extends RecyclerView {
public ExpandableRecyclerView(Context context) {
super(context, null);
initRecycler();
}
public ExpandableRecyclerView(Context context, AttributeSet attrs) {
super(context, attrs);
initRecycler();
}
public ExpandableRecyclerView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
initRecycler();
}
private void initRecycler() {
setClipToPadding(false);
setItemAnimator(new DefaultItemAnimator());
}
@Override
public Parcelable onSaveInstanceState() {
//begin boilerplate code that allows parent classes to save state
Parcelable superState = super.onSaveInstanceState();
SavedState ss = new SavedState(superState);
//end
if (getAdapter() != null)
ss.stateToSave = ((Adapter) this.getAdapter()).getExpandedGroups();
return ss;
}
@Override
public void onRestoreInstanceState(Parcelable state) {
//begin boilerplate code so parent classes can restore state
if (!(state instanceof SavedState)) // if state is not instance of out SaveState just restore in reg way
{
super.onRestoreInstanceState(state);
return;
}
// else if cast him to SavedState
SavedState ss = (SavedState) state;
super.onRestoreInstanceState(ss.getSuperState());
//end
if (getAdapter() != null)
((Adapter) getAdapter()).setExpandedGroups(ss.stateToSave);
}
@Override
public void setAdapter(RecyclerView.Adapter adapter) {
if (!(adapter instanceof Adapter))
throw new IllegalArgumentException("adapter has to be of type ExpandableRecyclerView.Adapter");
super.setAdapter(adapter);
}
public interface OnChildItemClickedListener {
void onChildItemClicked(int group, int position);
}
static class SavedState implements Parcelable {
public static final SavedState EMPTY_STATE = new SavedState() {
};
//required field that makes Parcelables from a Parcel
public static final Creator<SavedState> CREATOR =
new Creator<SavedState>() {
public SavedState createFromParcel(Parcel in) {
return new SavedState(in);
}
public SavedState[] newArray(int size) {
return new SavedState[size];
}
};
SparseBooleanArray stateToSave;
Parcelable superState;
SavedState() {
superState = null;
}
SavedState(Parcelable superState) {
this.superState = superState != EMPTY_STATE ? superState : null;
}
private SavedState(Parcel in) {
Parcelable superState = in.readParcelable(ExpandableRecyclerView.class.getClassLoader());
this.superState = superState != null ? superState : EMPTY_STATE;
this.stateToSave = in.readSparseBooleanArray();
}
@Override
public int describeContents() {
return 0;
}
@Override
public void writeToParcel(@NonNull Parcel out, int flags) {
out.writeParcelable(superState, flags);
out.writeSparseBooleanArray(this.stateToSave);
}
public Parcelable getSuperState() {
return superState;
}
}
public static abstract class Adapter<CVH extends ViewHolder, GVH extends ViewHolder, C, G> extends RecyclerView.Adapter<ViewHolder> {
private static final int TYPE_HEADER = 0;
SparseBooleanArray expanded = new SparseBooleanArray();
private OnChildItemClickedListener onChildItemClickedListener;
public Adapter() {
}
boolean isExpanded(int group) {
return expanded.get(group);
}
SparseBooleanArray getExpandedGroups() {
return expanded;
}
public void setExpandedGroups(SparseBooleanArray expanded) {
this.expanded = expanded;
}
public void expand(int group) {
if (isExpanded(group))
return;
// this lines of code calculate number of shown item in recycler view. also group is counting .
int position = 0;
for (int i = 0; i < group; i++) {
position++;
if (isExpanded(i))
position += getChildItemCount(i);
}
position++; // this for percent group
notifyItemRangeInserted(position, getChildItemCount(group)); // notify recycler view for expanding
expanded.put(group, true); // save expanding in sparce array
}
public void collapse(int group) {
if (!isExpanded(group)) // if is not expanded . so nothing to collapse.
return;
int position = 0;
for (int i = 0; i < group; i++) {
position++;
if (isExpanded(i))
position += getChildItemCount(i); // item
}
position++;
notifyItemRangeRemoved(position, getChildItemCount(group));
expanded.put(group, false);
}
public abstract int getGroupItemCount();
public abstract int getChildItemCount(int group);
@Override
public int getItemCount() {
int count = 0;
for (int i = 0; i <= getGroupItemCount(); i++) {
count += isExpanded(i) ? getChildItemCount(i) + 1 : 1;
}
return count;
}
public abstract G getGroupItem(int position);
public abstract C getChildItem(int group, int position);
public Object getItem(int i) {
int group = 0;
while (group <= getGroupItemCount()) {
if (i > 0 && !isExpanded(group)) {
i--;
group++;
continue;
}
if (i > 0 && isExpanded(group)) {
i--;
if (i < getChildItemCount(group))
return getChildItem(group, i);
i -= getChildItemCount(group);
group++;
continue;
}
if (i == 0)
return getGroupItem(group);
}
throw new IndexOutOfBoundsException();
}
@Override
public void onBindViewHolder(ViewHolder holder, int i) {
int group = 0;
while (group <= getGroupItemCount()) {
if (i > 0 && !isExpanded(group)) {
i--;
group++;
continue;
}
if (i > 0 && isExpanded(group)) {
i--;
if (i < getChildItemCount(group)) {
onBindChildViewHolder((CVH) holder, group, i);
return;
}
i -= getChildItemCount(group);
group++;
continue;
}
if (i == 0) {
onBindGroupViewHolder((GVH) holder, group);
return;
}
}
throw new IndexOutOfBoundsException();
}
@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
return viewType == TYPE_HEADER ? onCreateGroupViewHolder(parent) : onCreateChildViewHolder(parent, viewType);
}
protected abstract GVH onCreateGroupViewHolder(ViewGroup parent);
protected abstract CVH onCreateChildViewHolder(ViewGroup parent, int viewType);
public abstract int getChildItemViewType(int group, int position);
@Override
public int getItemViewType(int i) {
int group = 0;
while (group <= getGroupItemCount()) {
if (i > 0 && !isExpanded(group)) {
i--;
group++;
continue;
}
if (i > 0 && isExpanded(group)) {
i--;
if (i < getChildItemCount(group))
return getChildItemViewType(group, i);
i -= getChildItemCount(group);
group++;
continue;
}
if (i == 0)
return TYPE_HEADER;
}
throw new IndexOutOfBoundsException();
}
public void setOnChildItemClickedListener(OnChildItemClickedListener onItemClickedListener) {
this.onChildItemClickedListener = onItemClickedListener;
}
public void onBindChildViewHolder(CVH holder, final int group, final int position) {
holder.itemView.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
if (Adapter.this.onChildItemClickedListener != null) {
Adapter.this.onChildItemClickedListener.onChildItemClicked(group, position);
}
}
});
}
public void onBindGroupViewHolder(final GVH holder, final int group) {
if (holder instanceof GroupViewHolder)
((GroupViewHolder) holder).setExpanded(isExpanded(group));
holder.itemView.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
if (isExpanded(group)) {
collapse(group);
if (holder instanceof GroupViewHolder)
((GroupViewHolder) holder).collapse();
} else {
expand(group);
if (holder instanceof GroupViewHolder)
((GroupViewHolder) holder).expand();
}
}
});
}
}
public static abstract class GroupViewHolder extends ViewHolder {
public GroupViewHolder(View itemView) {
super(itemView);
}
public abstract void expand();
public abstract void collapse();
public abstract boolean isExpanded();
public abstract void setExpanded(boolean expanded);
}
public static class SimpleGroupViewHolder extends GroupViewHolder {
ImageView expandedIndicator;
TextView text;
private boolean expanded;
public SimpleGroupViewHolder(Context context) {
super(View.inflate(context, R.layout.group_header, null));
itemView.setLayoutParams(new LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT));
expandedIndicator = (ImageView) itemView.findViewById(R.id.carbon_groupExpandedIndicator);
text = (TextView) itemView.findViewById(R.id.carbon_groupText);
}
public SimpleGroupViewHolder(Context context, int layout) {
super(View.inflate(context, layout, null));
itemView.setLayoutParams(new LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT));
expandedIndicator = (ImageView) itemView.findViewById(R.id.carbon_groupExpandedIndicator);
text = (TextView) itemView.findViewById(R.id.carbon_groupText);
}
public void expand() {
ValueAnimator animator = ValueAnimator.ofFloat(0, 1);
animator.setInterpolator(new DecelerateInterpolator());
animator.setDuration(200);
animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
@Override
public void onAnimationUpdate(ValueAnimator animation) {
ViewHelper.setRotation(expandedIndicator, 180 * (float) (animation.getAnimatedValue()));
expandedIndicator.postInvalidate();
}
});
animator.start();
expanded = true;
}
public void collapse() {
ValueAnimator animator = ValueAnimator.ofFloat(1, 0);
animator.setInterpolator(new DecelerateInterpolator());
animator.setDuration(200);
animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
@Override
public void onAnimationUpdate(ValueAnimator animation) {
ViewHelper.setRotation(expandedIndicator, 180 * (float) (animation.getAnimatedValue()));
expandedIndicator.postInvalidate();
}
});
animator.start();
expanded = false;
}
@Override
public boolean isExpanded() {
return expanded;
}
public void setExpanded(boolean expanded) {
ViewHelper.setRotation(expandedIndicator, expanded ? 180 : 0);
this.expanded = expanded;
}
public String getText() {
return text.getText().toString();
}
public void setText(String t) {
text.setText(t);
}
}
}
答案 0 :(得分：1)
我得到了这些问题的答案：
- 如何在我打开活动时将我的一个或多个项目设置为展开。
在为RecyclerView设置适配器之前，我使用了expand（）方法，如下所示：
RecyclerView rv = (RecyclerView) findViewById(R.id.rv);
MyAdapter adapter = new MyAdapter(getContext(), R.layout.group_header);
adapter.expand(0); // 0 will expand the first Item.
rv.setAdapter(adapter);
- 一种制作我自己的标题布局的方法。
您需要做的就是创建自己的组头，如下所示：
static class GroupViewHolder extends ExpandableRecyclerView.GroupViewHolder {
ImageView expandedIndicator;
TextView text1;
TextView text2;
private boolean expanded;
GroupViewHolder(Context context, int layout) {
super(View.inflate(context, layout, null));
itemView.setLayoutParams(new RecyclerView.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT));
expandedIndicator = (ImageView) itemView.findViewById(R.id.groupExpandedIndicator);
text1 = (TextView) itemView.findViewById(R.id.text1);
text2 = (TextView) itemView.findViewById(R.id.text2);
}
public void expand() {
ValueAnimator animator = ValueAnimator.ofFloat(0, 1);
animator.setInterpolator(new DecelerateInterpolator());
animator.setDuration(200);
animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
@Override
public void onAnimationUpdate(ValueAnimator animation) {
ViewHelper.setRotation(expandedIndicator, 180 * (float) (animation.getAnimatedValue()));
expandedIndicator.postInvalidate();
}
});
animator.start();
expanded = true;
}
public void collapse() {
ValueAnimator animator = ValueAnimator.ofFloat(1, 0);
animator.setInterpolator(new DecelerateInterpolator());
animator.setDuration(200);
animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
@Override
public void onAnimationUpdate(ValueAnimator animation) {
ViewHelper.setRotation(expandedIndicator, 180 * (float) (animation.getAnimatedValue()));
expandedIndicator.postInvalidate();
}
});
animator.start();
expanded = false;
}
@Override
public boolean isExpanded() {
return expanded;
}
public void setExpanded(boolean expanded) {
ViewHelper.setRotation(expandedIndicator, expanded ? 180 : 0);
this.expanded = expanded;
}
void setText1(String t) {
text1.setText(t);
}
void setText2(String t) {
text2.setText(t);
}
}