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我想在我的應用程序中創建ExpandableListView。它有兩組：第一組是顏色，第二組是符號。第一組點擊工作正常。然而，第二組顯示來自第一組的行（如果第二組中有更多項目，那麼'額外'項目將是正確的）。如何使用Viewholder和ExpandableListView？
例如，讓我們說的「顏色」是白色，黑色，紅色和藍色，而符號「/」和「」。
如果我開始活動並單擊顏色，則它們顯示正確。如果我點擊'符號'，我會看到白色和黑色。
如果我點擊「符號」第一，那麼，我認爲「/」和「‘但是當我然後點擊顏色我看到‘/’，’。」，紅，藍。
我在網上搜索，並建立了我需要使用ViewHolders，以避免重複使用相同的看法時，我改變組。儘管如此，我還是無法實現它。起初它沒有任何區別，當我點擊第二組時，當前版本崩潰了。我認爲問題的一部分是我爲每個組別設置了不同的子佈局（即符號顯示與顏色不同）。
目前這裏是我已（我已經證明我的想法是相關的位;如果我漏掉了什麼重要的東西，我可以將它添加）：
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;
}
}
佈局父（ 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>
佈局的顏色行（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>
和用於符號行（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>
如果單擊「顏色」第一組，然後將「符號」基團，它崩潰出來就行：symbolviewholder =（SymbolViewHolder）行.getTag（）;
我真的很感激任何幫助。謝謝！
您能添加一部分異常的堆棧跟蹤嗎？ –
嘗試每次都使用新的行視圖，不要檢查如果row == null並且每次都創建新行並檢查 – Vickyexpert
@Vickyexpert每次創建一個新行都會禁用視圖回收，這是不好的。它也使ViewHolders無用。 – BladeCoder