高级极客。
我想请求一个简单但完全有效的示例，说明如何实现ExpandableListView，同时从BaseExpandableListAdapter扩展，从Sqlite数据库中读取数据。
我已经对这个问题进行了研究和实验（参见here），但是我能够在标题中显示一些数据的成功率很低，尽管它对所有组标题都重复相同的值。儿童用品也不显示。
使用BaseExpandableListAdapter进行扩展的原因是为组头设置了自定义布局。 SQLite访问的原因很自然，因为我的数据存储在那里。
到目前为止在网上搜索的所有示例都使用SimpleCursorTreeAdapter或CursorTreeAdapter作为基于数据库的应用程序中的扩展程序，或者当使用数据时使用BaseExpandableListAdapter在ArrayLists中。
以下是迄今为止的实验。 （使用此代码，只有组头标题一遍又一遍地填充相同的数字。不显示Childitems）
public class ExpandableListViewAdapterCustom extends BaseExpandableListAdapter {
protected Activity currentActivity;
public ExpandableListViewAdapterCustom(Activity callingActivity){
this.currentActivity = callingActivity;
}
private Cursor mGroupsCursorLocal ;
private Cursor mChildCursor;
private Context ctx;
private int groupItem;
private int childItem;
private String[] fieldsToUseFromGroupCursor;
private int[] screenTextsToMapGroupDataTo;
private String[] fieldsToUseFromChildCursor;
private int[] screenTextsToMapChildDataTo;
public ArrayList<String> tempChild;
public LayoutInflater minflater;
public Activity activity;
public int intGroupTotal;
public void setCurrentActivity(Activity activity) {
this.activity = activity;
}
public void setCtx(Context ctx) {
this.ctx = ctx;
}
public void setGroupItem(int groupItem) {
this.groupItem = groupItem;
}
public void setChildItem(int childItem) {
this.childItem = childItem;
}
public Activity getCurrentActivity() {
return currentActivity;
}
public Cursor getmGroupsCursorLocal() {
return mGroupsCursorLocal;
}
public Context getCtx() {
return currentActivity.getBaseContext();
}
public void setmGroupsCursorLocal(Cursor mGroupsCursor) {
this.mGroupsCursorLocal = mGroupsCursor;
}
public ExpandableListViewAdapterCustom(Cursor mGroupsCursor,
Activity activity,
int groupItem,
int childItem,
String[] fieldsToUseFromGroupCursor,
int[] screenTextsToMapGroupDataTo,
String[] fieldsToUseFromChildCursor,
int[] screenTextsToMapChildDataTo) {
DatabaseRoutines db = new DatabaseRoutines(activity);
setmGroupsCursorLocal(mGroupsCursor);
mGroupsCursorLocal = db.fetchGroup();
activity.startManagingCursor (mGroupsCursor);
mGroupsCursorLocal.moveToFirst();
mChildCursor=db.fetchChildren(mGroupsCursorLocal.getColumnIndex("Year"));
mChildCursor.moveToFirst();
activity.startManagingCursor(mChildCursor);
setCtx(activity);
setCurrentActivity(activity);
}
public void setInflater(LayoutInflater mInflater, Activity act) {
this.minflater = mInflater;
activity = act;
}
@Override
public Object getChild(int groupPosition, int childPosition) {
return null;
}
@Override
public long getChildId(int groupPosition, int childPosition) {
return 0;
}
@Override
public View getChildView(int groupPosition,
int childPosition,boolean
isLastChild,
View convertView,
ViewGroup parent) {
View v = convertView;
if (v == null)
{
LayoutInflater inflater =
(LayoutInflater) ctx.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
v = inflater.inflate(R.layout.exp_listview_childrow, parent, false);
}
TextView txtMonth = (TextView) v.findViewById(R.id.txtMonth);
TextView txtMonthAmountSent = (TextView)
v.findViewById(R.id.txtMonthAmountSentValue);
TextView txtMonthReceived = (TextView)
v.findViewById(R.id.txtMonthAmountReceivedValue);
txtMonth.setText(mChildCursor.getString(mChildCursor.getColumnIndex("Month")));
txtMonthAmountSent.setText
(mChildCursor.getString(mChildCursor.getColumnIndex("TotalSent")));
txtMonthReceived.setText
(mChildCursor.getString(mChildCursor.getColumnIndex("TotalReceived")));
return v;
}
@Override
public int getChildrenCount(int groupPosition) {
return (mChildCursor.getCount());
}
@Override
public Object getGroup(int groupPosition) {
return null;
}
@Override
public int getGroupCount() {
return mGroupsCursorLocal.getCount();
}
@Override
public void onGroupCollapsed(int groupPosition) {
super.onGroupCollapsed(groupPosition);
}
@Override
public void onGroupExpanded(int groupPosition) {
super.onGroupExpanded(groupPosition);
}
@Override
public long getGroupId(int groupPosition) {
return 0;
}
@Override
public View getGroupView(
int groupPosition,
boolean isExpanded,
View convertView,
ViewGroup parent)
{
View v = convertView;
if (v == null) {
LayoutInflater inflater =
(LayoutInflater) ctx.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
v = inflater.inflate(R.layout.exp_listview_groupheader, parent, false);
}
TextView txtYear = (TextView) v.findViewById(R.id.txtYearValue);
TextView txtAmountSent = (TextView) v.findViewById(R.id.txtAmountSentValue);
TextView txtAmountRecieved = (TextView)
v.findViewById(R.id.txtAmountReceivedValue);
txtYear.setText(mGroupsCursorLocal.getString(
mGroupsCursorLocal.getColumnIndex("Year")));
txtAmountSent.setText(
mGroupsCursorLocal.getString(mGroupsCursorLocal.getColumnIndex("TotalSent")));
txtAmountRecieved.setText(
GroupsCursorLocal.getString(mGroupsCursorLocal.getColumnIndex("TotalReceived")));
return v;
}
@Override
public boolean hasStableIds() {
return true;
}
@Override
public boolean isChildSelectable(int groupPosition, int childPosition) {
return false;
}
}
数据库代码是这样的
public Cursor fetchGroup() {
SQLiteDatabase db = this.getReadableDatabase(); //if memory leaks check here
String query = "SELECT DISTINCT MIN(ID) AS id,
Year, SUM(SentAmount) AS TotalSent, SUM(ReceivedAmount) AS TotalReceived
FROM MyTbl GROUP BY Year ORDER BY Year DESC ";
return db.rawQuery(query, null);}
public Cursor fetchChildren(int Yr) {
SQLiteDatabase db = this.getReadableDatabase(); //if memory leaks check here
String query = "SELECT MIN(ID) AS id,
Year, Month, SUM(SentAmount) AS TotalSent,
SUM(ReceivedAmount) AS TotalReceived
FROM MyTbl Where Year= "+ Yr +" GROUP BY Year,
Month ORDER BY Year DESC, Month DESC";
return db.rawQuery(query, null);
}
使用以下
从主要活动调用代码 ExpandableListView elv = (ExpandableListView)
findViewById(R.id.expandableListView);
ExpandableListAdapter mAdapter = new
ExpandableListViewAdapterCustom(mGroupsCursor,
MyActivity.this,
R.layout.exp_listview_groupheader,// Your row layout for a group
R.layout.exp_listview_childrow, // Your row layout for a child
new String[] { "Year",
"TotalSent",
"TotalReceived" },// Field(s) to use from group cursor
new int[] {R.id.txtYearValue,
R.id.txtAmountSentValue,
R.id.txtAmountReceivedValue },// Widget ids to put group data
into new String[] { "Year","Month",
"TotalSent",
"TotalReceived" }, // Field(s) to use from child cursors new
int[] {R.id.txtMonthValue,
R.id.txtMonthAmountSentValue,
R.id.txtMonthAmountReceivedValue});// Widget ids to put child d
data into
elv.setClickable(true);
elv.setAdapter(mAdapter); // set the
答案 0 :(得分：0)
经过近两周没有回答，我决定只使用一个使用ArrayLists的ExpandableListView示例并对其进行修改，以便ArrayLists由来自数据库的数据填充。它不是我想要的，但它的工作原理。我真的很惊讶，现在网上有一个使用ExpandableListview扩展形式BaseAdapter的例子，但是使用say cursorTreeAdapter或SimpleCursorAdapter从SQlite读取。 以下是我如何做到这一点，以防它将来帮助某人。显示的代码是从DB
填充ArrayList的位public ArrayList<ExpandListGroup> SetStandardGroups() {
ArrayList<ExpandListGroup> list = new ArrayList<ExpandListGroup>();
ArrayList<ExpandListChild> list2 = new ArrayList<ExpandListChild>();
int intMonthNum;
ExpandListGroup grp;
ExpandListChild chld;
//initialize db code here
DatabaseRoutines db = new DatabaseRoutines(this);
//create the Groups retreival cursor;
Cursor mGroupsCursor = db.fetchGroup();
//---the database call is done using this code which is in my
//---custom db class which implements the sqlhelper methods etc
//------start of db code snippet-------------------------------
//---public Cursor fetchGroup() {
//---SQLiteDatabase db = this.getReadableDatabase();
//--- String query = "SELECT DISTINCT MIN(ID) AS id, Year,
//--- SUM(SentAmount) AS TotalSent,
//--- SUM(ReceivedAmount) AS TotalReceived
//--- FROM Tbl GROUP BY Year ORDER BY Year DESC ";
//--- return db.rawQuery(query, null);}
//------end of db code snippet-------------------------------
mGroupsCursor.moveToFirst();
//method is depreciated from api14 but i'm targeting Gingerbread (api10) so i need to use it.
startManagingCursor(mGroupsCursor);
int intYear;
int intHeaderCounter = 0;
int intChildCounter = 0;
int intChildTotalCount = 0;
int intHeaderTotalGroupCount = mGroupsCursor.getCount();
//set the starting Year for the loop, if there is data;
if (intHeaderTotalGroupCount > 0) {
//get the first year
//intYear = mGroupsCursor.getInt(mGroupsCursor.getColumnIndex("Year"));
for (intHeaderCounter = 0; intHeaderCounter < intHeaderTotalGroupCount; intHeaderCounter++) {
grp = new ExpandListGroup();
intYear = mGroupsCursor.getInt(mGroupsCursor.getColumnIndex("Year"));
grp.setYear(intYear);
grp.setYearAmountReceived(mGroupsCursor.getDouble(mGroupsCursor.getColumnIndex("TotalReceived")));
grp.setYearAmountSent(mGroupsCursor.getDouble(mGroupsCursor.getColumnIndex("TotalSent")));
grp.setTag(mGroupsCursor.getString(mGroupsCursor.getColumnIndex("id")));
//Prepare counters for inner loop for child items of each
Cursor mChildCursor = db.fetchChildren(intYear);
mChildCursor.moveToFirst();
intChildTotalCount = mChildCursor.getCount();
//populate child items
for (intChildCounter = 0; intChildCounter < intChildTotalCount; intChildCounter++) {
chld = new ExpandListChild();
intMonthNum = mChildCursor.getInt(mChildCursor.getColumnIndex("Month"));
chld.setMonthNumber(intMonthNum);
chld.setTotalReceivedMonth(mChildCursor.getInt(mChildCursor.getColumnIndex("TotalReceived")));
chld.setTotalSentMonth(mChildCursor.getInt(mChildCursor.getColumnIndex("TotalSent")));
chld.setTag(mGroupsCursor.getString(mGroupsCursor.getColumnIndex("id")).toString());
list2.add(chld);
//grp.setItems(list2);
//move to next child record;
mChildCursor.moveToNext();
}
grp.setItems(list2);
list.add(grp);
list2 = new ArrayList<ExpandListChild>();
//move to next parent record;
mGroupsCursor.moveToNext();
}
} else {
log.d( "yourdebugtag_here", "Sorry, No Transactions Found.");
}
//db.close();
return list;
}