我正在尝试在我的应用中创建ExpandableListView。它有两组：第一组是颜色，第二组是符号。点击的第一组工作正常。但是，第二组显示第一组中的行（如果第二组中有更多项，那么'额外'将是正确的。）
例如，假设“颜色”为白色，黑色，红色和蓝色，符号为“/”和“。”。
如果我启动活动并单击颜色，则它们会正确显示。如果我点击“符号”，我会看到白色和黑色。
如果我先点击'符号'，那么我会看到'/'和'。'，但是当我点击颜色时，我会看到'/'，'。'，红色，蓝色。
我在线搜索并确定我需要使用ViewHolders以避免在我更改组时重复使用相同的视图。我虽然无法实现它。起初它没有任何区别，当我点击第二组时，当前版本崩溃了。我认为问题的一部分是每个组都有不同的子布局（即符号与颜色不同）。
目前这就是我所拥有的（我已经展示了我认为的相关内容;如果我遗漏了任何重要内容，我可以添加它）：
public class ColourSymbolKeyAdapter extends BaseExpandableListAdapter {
private Context context;
private HashMap<String, List<KeyItem>> childDataSource;
private List<String> parentDataSource;
public ColourSymbolKeyAdapter(Context context,
List<String> childParent,
HashMap<String, List<KeyItem>> child) {
this.context = context;
this.parentDataSource = childParent;
this.childDataSource = child;
}
... Left out various override functions ...
@Override
public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {
View v = convertView;
GroupViewHolder holder;
if(v == null) {
LayoutInflater inflater =
(LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
v = inflater.inflate(R.layout.expandablelist_parent, parent, false);
holder = new GroupViewHolder();
holder.mGroupName = (TextView) v.findViewById(R.id.textViewParent);
v.setTag(holder);
}else {
holder = (GroupViewHolder) v.getTag();
}
String parentHeader = (String) getGroup(groupPosition);
holder.mGroupName.setText(parentHeader);
return v;
}
@Override
public View getChildView(int groupPosition, int childPosition, boolean isLastChild, View convertView, ViewGroup parent) {
View row = convertView;
KeyItem childItem = (KeyItem) getChild(groupPosition, childPosition);
ColourViewHolder colourviewholder;
SymbolViewHolder symbolviewholder;
LayoutInflater inflater =
(LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
if(childItem.getPatternColour() == null) { // This is a symbol row
if(row == null) {
symbolviewholder = new SymbolViewHolder();
row = inflater.inflate(R.layout.expandablelist_child_symbol, parent, false);
symbolviewholder.mChildName = (TextView) row.findViewById(R.id.symbol_desc);
symbolviewholder.mSymbolCell = (SymbolCell) row.findViewById(R.id.symbol_cell);
row.setTag(symbolviewholder);
}else {
symbolviewholder = (SymbolViewHolder) row.getTag();
}
String drawableName = childItem.getPatternSymbol().getDrawable();
final int resourceId = context.getResources().getIdentifier(drawableName, "drawable", context.getPackageName());
Drawable drawable;
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
drawable = context.getResources().getDrawable(resourceId, context.getTheme());
} else {
drawable = context.getResources().getDrawable(resourceId);
}
symbolviewholder.mSymbolCell.setDrawable(drawable);
symbolviewholder.mChildName.setText(childItem.getPatternSymbol().getSymbolDescription());
}else { // This is a colour row
if(row == null) {
colourviewholder = new ColourViewHolder();
row = inflater.inflate(R.layout.expandablelist_child_colour, parent, false);
colourviewholder.mChildName = (TextView) row.findViewById(R.id.colour_name);
colourviewholder.mChildDesc = (TextView) row.findViewById(R.id.colour_desc);
colourviewholder.mColourCell = (ColourCell) row.findViewById(R.id.colour_cell);
row.setTag(colourviewholder);
}else {
colourviewholder = (ColourViewHolder) row.getTag();
}
colourviewholder.mColourCell.setColour(childItem.getPatternColour());
colourviewholder.mChildName.setText(childItem.getPatternColour().getName());
colourviewholder.mChildDesc.setText(childItem.getPatternColour().getDescription());
}
return row;
}
public final class GroupViewHolder {
TextView mGroupName;
}
public final class ColourViewHolder {
ColourCell mColourCell;
TextView mChildName, mChildDesc;
}
public final class SymbolViewHolder {
SymbolCell mSymbolCell;
TextView mChildName;
}
}
父级布局（expandablelist_parent.xml）：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/parentView">
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/textViewParent"
android:textColor="#000000"
android:textAppearance="@style/ParagraphBold">
</TextView>
</LinearLayout>
颜色行的布局（expandablelist_child_colour.xml）：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="@dimen/small_padding"
android:id="@+id/childViewColour"
android:orientation="horizontal">
<com.myname.appname.ColourCell xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="@dimen/grid_cell_column_width"
android:layout_height="@dimen/grid_cell_column_width"
android:id="@+id/colour_cell"
android:layout_marginRight="@dimen/small_padding" />
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textAppearance="@style/ParagraphBold"
android:textColor="@color/colorPrimaryDark"
android:id="@+id/colour_name">
</TextView>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textAppearance="@style/Paragraph"
android:textColor="@color/colorPrimaryDark"
android:id="@+id/colour_desc">
</TextView>
</LinearLayout>
</LinearLayout>
和符号行（expandablelist_child_symbol.xml）：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/childViewSymbol"
android:padding="@dimen/small_padding">
<com.myname.appname.SymbolCell xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="@dimen/grid_cell_column_width"
android:layout_height="@dimen/grid_cell_column_width"
android:textAppearance="@style/Paragraph"
android:id="@+id/symbol_cell"
android:layout_marginRight="@dimen/small_padding" />
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:textColor="@color/colorPrimaryDark"
android:id="@+id/symbol_desc">
</TextView>
</LinearLayout>
如果我先点击'颜色'组，然后点击'符号'组，它就会崩溃：symbolviewholder = (SymbolViewHolder) row.getTag()。
答案 0 :(得分：2)
由于您有2个不同的子布局，因此需要覆盖getChildTypeCount()和getChildType()，以便适配器将接收正确的视图类型以供重用。否则，在某些情况下，在尝试检索ViewHolder时会出现 ClassCastException 。
@Override
public int getChildTypeCount() {
return 2;
}
@Override
public int getChildType(int groupPosition, int childPosition) {
KeyItem childItem = (KeyItem) getChild(groupPosition, childPosition);
return (childItem.getPatternColour() == null) ? 0 : 1;
}
有关详细信息，请参阅HeterogeneousExpandableList文档。
答案 1 :(得分：1)
我认为使用Expendable Recyclerview使用自定义viewholder解决您的问题会更好。有关详细信息，请参阅链接。 https://guides.codepath.com/android/Heterogenous-Layouts-inside-RecyclerView
答案 2 :(得分：1)
您可以使用此library轻松实现此功能，有一个完整示例here。
基本上，您将项目分组为：
class MySection extends StatelessSection {
String header;
List<String> list;
boolean expanded = true;
public MySection(String header, List<String> list) {
// call constructor with layout resources for this Section header and items
super(R.layout.section_header, R.layout.section_item);
this.myHeader = header;
this.myList = list;
}
@Override
public int getContentItemsTotal() {
return expanded? list.size() : 0;
}
@Override
public RecyclerView.ViewHolder getHeaderViewHolder(View view) {
return new HeaderViewHolder(view);
}
@Override
public void onBindHeaderViewHolder(RecyclerView.ViewHolder holder) {
final HeaderViewHolder headerHolder = (HeaderViewHolder) holder;
headerHolder.tvTitle.setText(title);
headerHolder.rootView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
expanded = !expanded;
headerHolder.imgArrow.setImageResource(
expanded ? R.drawable.ic_keyboard_arrow_up_black_18dp : R.drawable.ic_keyboard_arrow_down_black_18dp
);
sectionAdapter.notifyDataSetChanged();
}
});
}
@Override
public RecyclerView.ViewHolder getItemViewHolder(View view) {
// return a custom instance of ViewHolder for the items of this section
return new MyItemViewHolder(view);
}
@Override
public void onBindItemViewHolder(RecyclerView.ViewHolder holder, int position) {
MyItemViewHolder itemHolder = (MyItemViewHolder) holder;
// bind your view here
itemHolder.tvItem.setText(list.get(position));
}
}
然后创建部分的实例并设置适配器：
// Create an instance of SectionedRecyclerViewAdapter
SectionedRecyclerViewAdapter sectionAdapter = new SectionedRecyclerViewAdapter();
// Add your Sections
sectionAdapter.addSection(new MySection("Colours", Arrays.asList(new String[] {"white", "red", "black", "blue" })));
sectionAdapter.addSection(new MySection("Symbols", Arrays.asList(new String[] {"/", "." })));
// Set up your RecyclerView with the SectionedRecyclerViewAdapter
RecyclerView recyclerView = (RecyclerView) findViewById(R.id.recyclerview);
recyclerView.setLayoutManager(new LinearLayoutManager(getContext()));
recyclerView.setAdapter(sectionAdapter);
答案 3 :(得分：1)
试试这个library。您可以用它重新ExpandableListView