如果SQLite游标没有结果,应用程序崩溃

Question

我有一个使用游标运行SQlite查询的应用程序.

    public Cursor totaltrips(){
    Cursor cursor = database.rawQuery("SELECT * AS TTotal FROM " + DatabaseHelper.TABLE_NAME, null);
    return cursor;
}

结果存储到最多5个值的Arraylist.如果数据库中没有记录,则应用程序崩溃.如果我有一个或多个数据库条目,它工作正常.有没有人知道如何在没有数据库条目时阻止它崩溃？

 // get column value
    if (Distance.moveToNext())
        result = String.valueOf(Distance.getDouble(Distance.getColumnIndex("myTotal")));

    tnmView.setText(result);

    List<String> distancearray = new ArrayList<String>();
    Cursor cursor =  dbManager.totaldistance();


    do{
        distancearray.add(cursor.getString(1));
    }while ((cursor.moveToNext()));
    ttrips = cursor.getCount();
    Log.i("Graph", "TTRIPS = " + ttrips);

    // Be sure here to have at least the 5 desired elements into the list
    while(distancearray.size() < 5){
        distancearray.add("0");
    }

该应用程序因错误而崩溃

android.database.CursorIndexOutOfBoundsException: Index 0 requested, with a size of 0

在线上

do{
        distancearray.add(cursor.getString(1));
    }while ((cursor.moveToNext()));

Answer 1

检查光标是否确实有结果,尝试这样的例子:

int numResults = cursor.getCount();
if (numResults > 0) {
    do {
        distancearray.add(cursor.getString(1));
    } while ((cursor.moveToNext()));
}