我有一个AdapterView，它会显示一个列表和标题，用于分隔不同的列表类别。该列表由具有用户输入的SQLite数据库填充。到目前为止一切正常。
我想在标题类别中没有项目时删除标题。代码如下：
public View getView(int position, View convertView, ViewGroup parent)
{
int viewType = getItemViewType(position);
if (viewType == TYPE_NORMAL)
{
// If the convertView is a textview (group), ignore it
if (convertView instanceof TextView)
{
convertView = null;
}
final int mapCursorPos = getInteralItemPosition(position);
return super.getView(mapCursorPos, convertView, parent);
}
else
{
// Check if it's a text view
TextView text;
if (convertView == null || !(convertView instanceof TextView))
{
((ListView) parent).setDivider(null);
((ListView) parent).setDividerHeight(0);
text = (TextView) inflater.inflate(R.layout.main_list_group, parent, false);
}
else
{
text = (TextView) convertView;
}
final String group = groupsIndexer.get(position).getName(resources);
//Code to hide menu title.
text.setText(group);
text.setVisibility(View.INVISIBLE);
myCursor = getCursor();
initCols(myCursor);
myCursor.moveToFirst();
while (myCursor.isAfterLast() == false)
{
String groupCursor = getGroup(myCursor).getName(resources);
if (groupCursor == group)
{
text.setHeight(12);
text.setPadding(20, 10, 0, 10);
text.setVisibility(View.VISIBLE);
}
myCursor.moveToNext();
}
return text;
}
}
所以，正如你所看到的那样，我开始将文本设置为不可见，然后查询数据库以检查其特定类别中是否有任何项目，如果有，我将可见性设置为可见。
然而，当返回时，该方法似乎忽略了while循环中的任何内容。是不是可以通过这样的getView()单独格式化每个textview对象？
提前致谢。
答案 0 :(得分：1)
这应该会让你朝着正确的方向前进。
import java.util.ArrayList;
import java.util.Collections;
import android.content.Context;
import android.database.Cursor;
import android.database.DataSetObserver;
import android.graphics.Paint;
import android.text.format.DateUtils;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;
public class GroupedListAdapter extends BaseAdapter
{
private static final int TYPE_NORMAL = 0;
private static final int TYPE_GROUP = 1;
private static final int MAX_TYPES = 2;
private final Context mContext;
private final LayoutInflater mInflater;
private final ContactManager mContactManager;
private final ArrayList<GroupItem> mItems = new ArrayList<GroupItem>();
private final DataSetObserver mDataSetObserver = new MyDataSetObserver();
private boolean mDataValid = false;
private Cursor mCursor = null;
private int mIndexId;
private int mIndexSummary;
private int mIndexType;
private int mIndexSender;
private int mIndexReciever;
private int mIndexCompleted;
private int mIndexCompletedBy;
public GroupedListAdapter(Context context)
{
mContext = context;
mContactManager = new ContactManager(context);
mInflater = LayoutInflater.from(context);
}
public void changeCursor(Cursor newCursor)
{
if(newCursor == mCursor){
return;
}
Cursor oldCursor = mCursor;
if(oldCursor != null) {
if(mDataSetObserver != null){
oldCursor.unregisterDataSetObserver(mDataSetObserver);
}
}
mCursor = newCursor;
if(newCursor != null){
if(mDataSetObserver != null){
newCursor.registerDataSetObserver(mDataSetObserver);
}
mIndexId = newCursor.getColumnIndexOrThrow(DatabaseContract.Task.Columns._ID);
mIndexSummary = newCursor.getColumnIndexOrThrow(DatabaseContract.Task.Columns.SUMMARY);
mIndexType = newCursor.getColumnIndexOrThrow(DatabaseContract.Task.Columns.TYPE);
mIndexSender = newCursor.getColumnIndexOrThrow(DatabaseContract.Task.Columns.SENDER);
mIndexReciever = newCursor.getColumnIndexOrThrow(DatabaseContract.Task.Columns.RECIEVER);
mIndexCompleted = newCursor.getColumnIndexOrThrow(DatabaseContract.Task.Columns.COMPLETED);
mIndexCompletedBy = newCursor.getColumnIndexOrThrow(DatabaseContract.Task.Columns.COMPLETED_BY);
// calculate types and index mappings
/*
* 1. Sent (5)
* 2. Item 5
* 3. Item 6
* 4. Received (9)
* 5. Item 9
* 6. Today (1)
* 7. Item 1
* 8. Item 2
* 9. Item 3
*
*/
// allocate
int count = newCursor.getCount();
mItems.ensureCapacity(count);
if(newCursor.moveToFirst()){
int i = 0;
do{
mItems.add(new GroupItem(getGroupId(newCursor), i, TYPE_NORMAL));
i++;
}while(newCursor.moveToNext());
}
Collections.sort(mItems);
int lastGroupId = -1;
for(int i = 0; i < mItems.size(); i++){
final GroupItem item = mItems.get(i);
if(lastGroupId != item.group_id){
mItems.add(i, new GroupItem(item, TYPE_GROUP));
lastGroupId = item.group_id;
}
}
mDataValid = true;
// notify the observers about the new cursor
notifyDataSetChanged();
}
else{
mDataValid = false;
mIndexId = -1;
mIndexSummary = -1;
mIndexType = -1;
mIndexSender = -1;
mIndexReciever = -1;
mIndexCompleted = -1;
mIndexCompletedBy = -1;
mItems.clear();
// notify the observers about the lack of a data set
notifyDataSetInvalidated();
}
if(oldCursor != null) {
oldCursor.close();
}
}
@Override
public View getView(int position, View convertView, ViewGroup parent)
{
if(!mDataValid) {
throw new IllegalStateException("this should only be called when the cursor is valid");
}
GroupItem item = mItems.get(position);
if(!mCursor.moveToPosition(item.position)) {
throw new IllegalStateException("couldn't move cursor to position " + position);
}
final View view;
if(convertView == null) {
if(item.type == TYPE_GROUP){
view = mInflater.inflate(R.layout.main_list_group, parent, false);
}
else if(item.type == TYPE_NORMAL){
view = mInflater.inflate(R.layout.main_list_item, parent, false);
}
else{
throw new IllegalStateException("Bad TaskItem type");
}
}
else{
view = convertView;
}
if(item.type == TYPE_GROUP){
TextView textGroup = (TextView)view.findViewById(R.id.task_group);
textGroup.setText(mContext.getString(item.group_id));
}
else if(item.type == TYPE_NORMAL){
TextView textTitle = (TextView)view.findViewById(R.id.task_title);
TextView textDescr = (TextView)view.findViewById(R.id.task_description);
String desc;
String type = mCursor.getString(mIndexType);
if(type.equals(DatabaseContract.Task.TASK_TYPE_OWNER)){
desc = mContext.getString(R.string.desc_example);
}
else if(type.equals(DatabaseContract.Task.TASK_TYPE_RECEV)){
final String sender = mCursor.getString(mIndexSender);
final String name = mContactManager.getContactName(sender);
desc = (name != null) ? name : sender;
}
else{
final String receiver = mCursor.getString(mIndexReciever);
final String name = mContactManager.getContactName(receiver);
desc = (name != null) ? name : receiver;
}
textDescr.setText(desc);
String title = mCursor.getString(mIndexSummary);
textTitle.setText(Character.toUpperCase(title.charAt(0)) + title.substring(1));
if(mCursor.getInt(mIndexCompleted) != 0){
textTitle.setPaintFlags(textTitle.getPaintFlags() | Paint.STRIKE_THRU_TEXT_FLAG);
}
else{
textTitle.setPaintFlags(textTitle.getPaintFlags() & ~Paint.STRIKE_THRU_TEXT_FLAG);
}
}
return view;
}
@Override
public Cursor getItem(int position)
{
if(mDataValid && mCursor != null){
mCursor.moveToPosition(mItems.get(position).position);
return mCursor;
}
else{
return null;
}
}
@Override
public long getItemId(int position)
{
if(mDataValid && mCursor != null){
if(mCursor.moveToPosition(mItems.get(position).position)){
return mCursor.getLong(mIndexId);
}
else{
return 0;
}
}
else{
return 0;
}
}
@Override
public int getItemViewType(int position)
{
if(mDataValid && mCursor != null){
return mItems.get(position).type;
}
else{
return IGNORE_ITEM_VIEW_TYPE;
}
}
@Override
public int getViewTypeCount()
{
return MAX_TYPES;
}
@Override
public int getCount()
{
if(mDataValid && mCursor != null){
return mItems.size();
}
else{
return 0;
}
}
public Cursor getCursor()
{
return mCursor;
}
@Override
public boolean hasStableIds()
{
return true;
}
private int getGroupId(Cursor c)
{
if(c.getString(mIndexType).equals(DatabaseContract.Task.TASK_TYPE_SENT)){
return R.string.group_sent;
}
else if(c.getString(mIndexType).equals(DatabaseContract.Task.TASK_TYPE_RECEV)){
return R.string.group_received;
}
else{
long time = c.getLong(mIndexCompletedBy);
long delta = (time - System.currentTimeMillis());
if(delta <= DateUtils.HOUR_IN_MILLIS){
return R.string.group_asap;
}
else if(delta <= DateUtils.DAY_IN_MILLIS){
return R.string.group_today;
}
else if(delta <= (DateUtils.DAY_IN_MILLIS * 2)){
return R.string.group_tomorrow;
}
else if(delta <= DateUtils.WEEK_IN_MILLIS){
return R.string.group_this_week;
}
else if(delta <= (DateUtils.WEEK_IN_MILLIS * 2)){
return R.string.group_next_week;
}
else{
return R.string.group_someday;
}
}
}
private class MyDataSetObserver extends DataSetObserver
{
@Override
public void onChanged()
{
mDataValid = true;
notifyDataSetChanged();
}
@Override
public void onInvalidated()
{
mDataValid = false;
notifyDataSetInvalidated();
}
}
private static class GroupItem implements Comparable<GroupItem>
{
public int group_id;
public int position;
public int type;
public GroupItem(int group_id, int position, int type)
{
this.group_id = group_id;
this.position = position;
this.type = type;
}
public GroupItem(GroupItem item, int type)
{
this.group_id = item.group_id;
this.position = item.position;
this.type = type;
}
@Override
public int compareTo(GroupItem another)
{
return group_id < another.group_id ? -1 : (group_id == another.group_id ? 0 : 1);
}
}
}
答案 1 :(得分：0)
将groupCursor == group更改为groupCursor.equals(group)。
BTW我建议在另一个线程中加载数据，而不是在UI线程中，特别是在getView方法中，因为ListView可以调用很多次