从SQLite数据库加载数据到ListView
问题描述：
我想从Android中的SQLite数据库加载数据并将其值设置为ListView。问题是，当我在OnCreate中加载数据时，它不会显示任何内容，但是当我刷新应用程序时，它会显示数据。从SQLite数据库加载数据到ListView
请帮我解决这个问题！
负载任务的代码：
public void loadTasks() {
Cursor c = notesDb.rawQuery("SELECT * FROM notes", null);
int titleIndex = c.getColumnIndex("title");
int contentIndex = c.getColumnIndex("content");
int dateIndex = c.getColumnIndex("date");
int idIndex = c.getColumnIndex("object");
if (c.moveToFirst()) {
if (!titles.isEmpty()) {
titles.clear();
}
if (!content.isEmpty()) {
content.clear();
}
if (!dates.isEmpty()) {
dates.clear();
}
if (!objectId.isEmpty()) {
objectId.clear();
}
do {
titles.add(c.getString(titleIndex));
content.add(c.getString(contentIndex));
dates.add(c.getString(dateIndex));
objectId.add(c.getString(idIndex));
Log.i("Title", c.getString(titleIndex));
Log.i("Content", c.getString(contentIndex));
Log.i("Date", c.getString(dateIndex));
Log.i("Id", c.getString(idIndex));
} while (c.moveToNext());
tasksList.setAdapter(customAdapter);
loadingBar.setVisibility(View.INVISIBLE);
} else {
if (titles.size() > 0 || content.size() > 0) {
tasksList.setAdapter(customAdapter);
loadingBar.setVisibility(View.INVISIBLE);
} else {
titles.add("Welcome To App !");
content.add("Start taking notes by clicking the add button below !");
final Calendar c1 = Calendar.getInstance();
final String monthName = new SimpleDateFormat("MMMM").format(c1.getTime());
dates.add(String.valueOf(monthName + " " + c1.get(Calendar.DAY_OF_MONTH)) + " " + c1.get(Calendar.YEAR));
objectId.add("randomId");
tasksList.setAdapter(customAdapter);
loadingBar.setVisibility(View.INVISIBLE);
}
}
}
的OnCreate代码
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_dolt);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
loadTasks();
传递数据的OnCreate到适配器：
customAdapter = new CustomAdapter(DoltActivity.this, titles, content, dates);
定制适配器代码：
public class CustomAdapter extends BaseAdapter{
ArrayList<String> title;
ArrayList<String> contents;
ArrayList<String> dates;
Context context;
private static LayoutInflater inflater=null;
public CustomAdapter(DoltActivity mainActivity, ArrayList<String> titles, ArrayList<String> content, ArrayList<String> date) {
// TODO Auto-generated constructor stub
title=titles;
contents=content;
dates=date;
context=mainActivity;
inflater = (LayoutInflater)context.
getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
@Override
public int getCount() {
// TODO Auto-generated method stub
return title.size();
}
@Override
public Object getItem(int position) {
// TODO Auto-generated method stub
return position;
}
@Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return position;
}
@Override
public int getItemViewType(int position) {
return CustomAdapter.IGNORE_ITEM_VIEW_TYPE;
}
public static class Holder
{
TextView tv;
TextView content;
TextView date;
}
@Override
public View getView(final int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
Holder holder = new Holder();
View rowView = null;
rowView = inflater.inflate(R.layout.custom_row, null);
holder.tv = (TextView) rowView.findViewById(R.id.textView10);
holder.content = (TextView) rowView.findViewById(R.id.textView3);
holder.date = (TextView) rowView.findViewById(R.id.textView4);
holder.tv.setText(title.get(position));
holder.content.setText(contents.get(position));
holder.date.setText(dates.get(position));
rowView.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
DoltActivity.tapped = true;
DoltActivity.id = position;
Log.i("Position", String.valueOf(position));
}
});
rowView.setOnLongClickListener(new View.OnLongClickListener() {
@Override
public boolean onLongClick(View view) {
DoltActivity.longTapped = true;
DoltActivity.id = position;
Log.i("Long ", "Tapped");
return true;
}
});
return rowView;
}
}
刷新代码：
swipeRefresh.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
@Override
public void onRefresh() {
loadTasks();
swipeRefresh.setRefreshing(false);
}
});
提前感谢！
答
试试这个，
初始化您customAdapter的loadTask()内将其设置为ListView控件之前，即前
customAdapter = new CustomAdapter(getActivity(), titles, content, dates);
tasksList.setAdapter(customAdapter);
有看起来像你的代码的逻辑数据流错误，初始化customAdapter在拨打loadTask()但在loadTask()之内后，您正在使用该对象，但未使用标题的更新列表对其进行初始化,内容和日期。
+0
谢谢！它现在有效 –
答
更新阵列后创建适配器。移动你行：
customAdapter = new CustomAdapter(DoltActivity.this, titles, content, dates);
是前：
tasksList.setAdapter(customAdapter);
也，可以在下面的代码移动到外面你如果只是删除代码重复。您loadTask功能如下：
public void loadTasks() {
Cursor c = notesDb.rawQuery("SELECT * FROM notes", null);
int titleIndex = c.getColumnIndex("title");
int contentIndex = c.getColumnIndex("content");
int dateIndex = c.getColumnIndex("date");
int idIndex = c.getColumnIndex("object");
if (c.moveToFirst()) {
if (!titles.isEmpty()) {
titles.clear();
}
if (!content.isEmpty()) {
content.clear();
}
if (!dates.isEmpty()) {
dates.clear();
}
if (!objectId.isEmpty()) {
objectId.clear();
}
do {
titles.add(c.getString(titleIndex));
content.add(c.getString(contentIndex));
dates.add(c.getString(dateIndex));
objectId.add(c.getString(idIndex));
Log.i("Title", c.getString(titleIndex));
Log.i("Content", c.getString(contentIndex));
Log.i("Date", c.getString(dateIndex));
Log.i("Id", c.getString(idIndex));
} while (c.moveToNext());
} else {
if (titles.size() > 0 || content.size() > 0) {
} else {
titles.add("Welcome To App !");
content.add("Start taking notes by clicking the add button below !");
final Calendar c1 = Calendar.getInstance();
final String monthName = new SimpleDateFormat("MMMM").format(c1.getTime());
dates.add(String.valueOf(monthName + " " + c1.get(Calendar.DAY_OF_MONTH)) + " " + c1.get(Calendar.YEAR));
objectId.add("randomId");
}
}
customAdapter = new CustomAdapter(DoltActivity.this, titles, content, dates);
tasksList.setAdapter(customAdapter);
loadingBar.setVisibility(View.INVISIBLE);
}
哪里是你的customAdapter代码，以及如何通过你的光标customAdapter。 – shanyour
@shanyour我也添加了这些代码！谢谢你通知我！ –