Android Cursor.Movetonext()

android cursor.moveToNext()?

For clarity a complete example would be as follows which I trust is of interest. As code comments indicated we essentially iterate over database rows and then columns to form a table of data as per database.

    Cursor cursor = getActivity().getContentResolver().query(uri, projection, null, null,
            null);

    //if the cursor isnt null we will essentially iterate over rows and then columns
    //to form a table of data as per database.
    if (cursor != null) {

        //more to the first row
        cursor.moveToFirst();

        //iterate over rows
        for (int i = 0; i < cursor.getCount(); i++) {

            //iterate over the columns
            for(int j = 0; j < cursor.getColumnNames().length; j++){ 

                //append the column value to the string builder and delimit by a pipe symbol
                stringBuilder.append(cursor.getString(j) + "|"); 
            }
            //add a new line carriage return
            stringBuilder.append("\n");

            //move to the next row
            cursor.moveToNext();
        }
        //close the cursor
        cursor.close();
    }

Is Android Cursor.moveToNext() Documentation Correct?

Verbatim from the API:

Returns:
whether the move succeeded.

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So, it means that:

Cursor in first row -> moveToNext() -> cursor in second row -> there's no second row -> return false

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If you want the details, go to the source: http://grepcode.com/file/repository.grepcode.com/java/ext/com.google.android/android/2.3.3_r1/android/database/AbstractCursor.java#AbstractCursor.moveToNext%28%29

public final boolean moveToNext() {
  return moveToPosition(mPos + 1);
}

public final boolean moveToPosition(int position) {
    // Make sure position isn't past the end of the cursor
    final int count = getCount();
    if (position >= count) {
        mPos = count;
        return false;
    }

Never entering in cursor.moveToNext() in Android SQLite

What you are doing with this:

String[] selectionArgs = {"'" + personCellString + "'"};

is searching for the string value of personCellString enclosed inside single quotes and not for the actual value of the string personCellString.

Remove the single quotes:

String[] selectionArgs = {personCellString};

You don't have to worry about the string representation of personCellString in the final sql statement that will be constructed and executed which will contain them without explicitly setting them.

while (cursor.moveToNext()) runs only once in android studio

If you want to loop over the cursor result set again, you need to rewind the cursor back to beginning. Replace the

while (cursor.moveToNext()) {
    ...
}

with

if (cursor.moveToFirst()) {
    do {
        ...
    } while (cursor.moveToNext());
}

and remove the cursor.close() as you're not yet done with your cursor.

Cursor.moveToNext error

You appear to be making a fairly large query: at least 1127 rows, and for all possible columns (despite the fact that you are only using two of them). And, during your work with that Cursor, you are doing disk I/O and/or IPC back to the ContentProvider, assuming that UsefulDocumentFile is related to Android's DocumentFile.

As Prakash notes, the Cursor that you get back may contain only a subset of the information. As soon as you try advancing past that point, the Cursor needs to go back to the data source and get the next window of results. I can see you running into this sort of problem if there has been a substantial change in the data while this work has been going on (e.g., there are now fewer than 1127 rows).

I suggest that you:

• Constrain the columns that you get back to the subset that you need, and

• Avoid the I/O during the loop (e.g., spin through the Cursor to build up an ArrayList<Pair> or something, close the Cursor, then iterate over the list)

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