【发布时间】：2010-07-26 20:21:28
【问题描述】：
我正在制作一个时间表程序，用户可以在其中输入他的出拳和出拳。我有一个从日历对象数组填充的 ListView。我希望每一行都显示日期和日期，然后在新的一行显示时间，但我只想显示与前一个元素不同的日期和日期。
目前，我根据使用 position 与 position-1 的比较（用作数组的索引）在 BaseAdapter 中设置可见性。这仅在整个列表适合屏幕时才有效。如果它超出屏幕并且用户滚动，结果是不可预测的。
为了进一步混淆，我根据位置设置时间的颜色，在绿色和红色（输入/输出）之间交替，它可以按预期工作，滚动与否。
Android 如何在滚动时处理 ListView 位置，或者我可以采取哪些不同的方式来显示/隐藏日期和日期？
public class TimeSheetActivity extends Activity {
SQLiteDatabase timesDatabase;
Cursor punchCursor;
private static Calendar[] allPunches;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.timesheet);
} //end onCreate()
@Override
public void onResume() {
super.onResume();
//Open database
timesDatabase = openOrCreateDatabase(
"times_database.db",
SQLiteDatabase.CREATE_IF_NECESSARY,
null);
timesDatabase.setLocale(Locale.getDefault());
timesDatabase.setLockingEnabled(true);
timesDatabase.setVersion(1);
punchCursor = timesDatabase.query("Timepunches", null, null, null, null, null, "punch ASC;");
updateTimeSheet();
} //end onResume()
@Override
public void onPause() {
super.onPause();
timesDatabase.close();
} //end onResume()
private static class EfficientAdapter extends BaseAdapter {
private LayoutInflater mInflater;
public EfficientAdapter(Context context) {
mInflater = LayoutInflater.from(context);
}
public int getCount() {
return allPunches.length;
}
public Object getItem(int position) {
return position;
}
public long getItemId(int position) {
return position;
}
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder;
if (convertView == null) {
convertView = mInflater.inflate(R.layout.time_list_row, null);
holder = new ViewHolder();
holder.text1 = (TextView) convertView.findViewById(R.id.day_textview);
holder.text2 = (TextView) convertView.findViewById(R.id.date_textview);
holder.text3 = (TextView) convertView.findViewById(R.id.times_this_day_textview);
convertView.setTag(holder);
}
else {
holder = (ViewHolder) convertView.getTag();
}
String dayNames[] = new DateFormatSymbols().getWeekdays();
//Initialize first list element
if (position < 1) {
holder.text1.setText(dayNames[allPunches[position].get(Calendar.DAY_OF_WEEK)]);
holder.text2.setText(formatDate(allPunches[position]));
}
else {
holder.text1.setText(dayNames[allPunches[position].get(Calendar.DAY_OF_WEEK)]);
holder.text2.setText(formatDate(allPunches[position]));
holder.text1.setVisibility(View.VISIBLE);
holder.text2.setVisibility(View.VISIBLE);
//Hide day and date if same as last
if (formatDate(allPunches[position]).contentEquals(formatDate(allPunches[position-1]))) {
holder.text1.setVisibility(View.GONE);
holder.text2.setVisibility(View.GONE);
}
}
holder.text3.setText(formatTime(allPunches[position], true) + " " + position);
//Color in/out punches
if (position%2 == 0) {
holder.text3.setTextColor(Color.GREEN);
}
else {
holder.text3.setTextColor(Color.RED);
}
return convertView;
} //end getView()
static class ViewHolder {
public TextView text1;
TextView text2;
TextView text3;
}
} //end EfficientAdapter
public void updateTimeSheet() {
punchCursor = timesDatabase.query("Timepunches", null, null, null, null, null, "punch ASC;");
allPunches = new Calendar[punchCursor.getCount()];
int i = 0; //for indexing allPunches
Calendar nextDay = Calendar.getInstance();
nextDay.setLenient(true);
//populate allPunches
for (punchCursor.moveToFirst(); !punchCursor.isAfterLast(); punchCursor.moveToNext()) {
allPunches[i] = Calendar.getInstance();
allPunches[i].setTimeInMillis(punchCursor.getLong(0));
++i;
} //end for
final ListView timeSheetListView = (ListView)findViewById(R.id.timesheet_listview);
timeSheetListView.setAdapter(new EfficientAdapter(this));
timeSheetListView.setOnItemClickListener(new OnItemClickListener() {...}); //end click listener for list item
} //end updateTimeSheet()
public static String formatTime(Calendar thisTime, boolean showAMPM) {...}
public static String formatDate(Calendar thisDate) {
String formattedDate = "";
formattedDate += thisDate.get(Calendar.MONTH) +"-"+ thisDate.get(Calendar.DAY_OF_MONTH) +"-"+ thisDate.get(Calendar.YEAR);
return formattedDate;
} //end formatDate()
} //结束时间表活动
【问题讨论】：