【发布时间】：2014-04-22 11:08:41
【问题描述】：
从数据库中以列表视图的形式显示的数据（这里列表视图的标题禁用了标题的onClick）。
我试图显示来自position 的getView() 的所选项目的描述。该列表非常大，因此它会在滚动时动态分配视图，而position 在滚动后会给出错误的值
我观看了Google I/O 2010 - The world of ListView 视频和it states these things。
所以我想我需要实现 notifyDataSetChanged() 或 onScroll() ， onScrollStateChanged() 方法。
但是怎么做呢？
代码：
public class MainActivity1 extends ListActivity implements OnTouchListener{
private MyCustomAdapter mAdapter;
Activity temp = this;
String []s = new String[500];
ArrayList<GS> q = new ArrayList<GS>();
CustomAdapter adapter;
ListView lv;
int c=1;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
DBAdapter db = DBAdapter.getDBAdapter(getApplicationContext());
if (!db.checkDatabase())
{
db.createDatabase(getApplicationContext());
}
db.openDatabase();
q = db.getData();
mAdapter = new MyCustomAdapter();
mAdapter.addSeparatorItem(q.get(0).getA_name());
mAdapter.addItem(q.get(0).getAS_name());
for (int i = 1; i < 460; i++) {
if (!(q.get(i).getA_name().trim().equals(q.get(i-1).getA_name().trim()))) {
mAdapter.addSeparatorItem(q.get(i).getA_name());
c++;
}
mAdapter.addItem(q.get(i).getAS_name());
}
setListAdapter(mAdapter);
}
//Adapter Class
private class MyCustomAdapter extends BaseAdapter {
private static final int TYPE_ITEM = 0;
private static final int TYPE_SEPARATOR = 1;
private static final int TYPE_MAX_COUNT = TYPE_SEPARATOR + 1;
private ArrayList<String> mData = new ArrayList<String>();
private LayoutInflater mInflater;
private TreeSet<Integer> mSeparatorsSet = new TreeSet<Integer>();
public MyCustomAdapter() {
mInflater = (LayoutInflater)getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
public void addItem(final String item) {
mData.add(item);
notifyDataSetChanged();
}
public void addSeparatorItem(final String item) {
mData.add(item);
// save separator position
mSeparatorsSet.add(mData.size() - 1);
notifyDataSetChanged();
}
@Override
public int getItemViewType(int position) {
return mSeparatorsSet.contains(position) ? TYPE_SEPARATOR : TYPE_ITEM;
}
@Override
public int getViewTypeCount() {
return TYPE_MAX_COUNT;
}
public int getCount() {
return mData.size();
}
public String getItem(int position) {
return mData.get(position);
}
public long getItemId(int position) {
Log.v("getItemId Position", ""+position);
return position;
}
public View getView(final int position, View convertView, ViewGroup parent) {
ViewHolder holder = null;
int type = getItemViewType(position);
// System.out.println("getView " + position + " " + convertView + " type = " + type);
if (convertView == null) {
holder = new ViewHolder();
switch (type) {
case TYPE_ITEM:
convertView = mInflater.inflate(R.layout.activity_main1, null);
holder.textView = (TextView)convertView.findViewById(R.id.text);
break;
case TYPE_SEPARATOR:
convertView = mInflater.inflate(R.layout.activity_main2, null);
holder.textView = (TextView)convertView.findViewById(R.id.textSeparator);
count++;
break;
}
convertView.setTag(holder);
} else {
holder = (ViewHolder)convertView.getTag();
}
holder.textView.setText(mData.get(position));
// We set the OnClickListener here because it is unique to every
// item. Although views can be recycled & reused, an OnClickListener cannot be.
if (type == TYPE_ITEM) {
holder.textView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
AlertDialog.Builder x = new AlertDialog.Builder(
temp);
Log.v("position",""+position);
x.setIcon(R.drawable.ic_launcher)
.setTitle(q.get(position-count).getAS_name())
.setMessage(q.get(position-count).getDesc_art())
.setCancelable(true)
.setPositiveButton("OK",
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface arg,
int arg1) {
}
});
AlertDialog a = x.create();
a.show();
}
});
} else {
holder.textView.setOnClickListener(null);
count++;
}
return convertView;
}
}
public static class ViewHolder {
public TextView textView;
}
public boolean onTouch(View v, MotionEvent event) {
// TODO Auto-generated method stub
return false;
}
}
所以，我试图在单击TYPE_ITEM 时在 Alertdialog 中显示所选项目的描述。每个 TYPE_ITEM 的描述按顺序存储在数据库中。因此，我需要跟踪 TYPE_ITEM 的位置（意味着索引）以从数据库中获取数据。我希望你现在明白我的问题了！
顺便说一句，我尝试在getView() 中使用计数变量，但是如果我们再次向上滚动会怎样（在这种情况下，count 应该递减）。我希望你现在明白这个问题，我认为我们应该实现 notifyDataSetChanged 或 onScroll、onScrollStateChanged 方法。
如果问题不清楚，可以在cmets问我
请帮忙！
【问题讨论】：
标签： android listview android-listview arraylist baseadapter