B4J Question B4XTable Crashes with 8 Columns But Not With 7

cklester · Nov 29, 2021

If you run the attached B4XPages project, the app will crash when you attempt to search the B4XTable.

If you comment out line 30, reducing the table column count from 8 to 7, you can search just fine. No problem.

I also tried with 9 and 999 rows. The number of rows does not seem to matter.

emexes · Nov 29, 2021

You've probably already tried this but, in the programming fog-of-war, sometimes things slip by ? :

is it possible, when you set the table to 8 columns, that B4XTable1.SetData is expecting newrow()s of 8 strings, not 7 ?

B4X:

Private newrow(7) As String
...
B4XTable1.SetData(randList)

cklester · Nov 29, 2021

emexes said:
is it possible, when you set the table to 8 columns, that B4XTable1.SetData is expecting newrow()s of 8 strings, not 7 ?

B4X:

Private newrow(7) As String ... B4XTable1.SetData(randList)

It's seemingly irrelevant, as both are receiving only newrows() of 4 strings.

In both cases, I am passing fewer-than-expected columns of data. Only the table with 8 columns crashes.

LucaMs · Nov 29, 2021

cklester said:
Only the table with 8 columns crashes.

It is not so. The size of the array must match the number of columns.

Try so, commenting/uncommenting some AddColumn lines.

B4X:

    Private randList As List
    randList.Initialize
    Private i As Int
    For i = 0 To 99
        Private newrow(B4XTable1.Columns.Size) As String
        Private x As Int
        For x = 0 To B4XTable1.Columns.Size - 1
            newrow(x) = RandomString(3)
        Next
        randList.Add(newrow)
    Next

    B4XTable1.SetData(randList)

emexes · Nov 29, 2021

cklester said:
Only the table with 8 columns crashes.

Try 8 table columns with:

B4X:

Private newrow(8) As String

cklester · Nov 29, 2021

LucaMs said:
The size of the array must match the number of columns.

If this were true, why does the table with 7 columns not crash?

Answer: Given @emexes answer above, it seems it is the size of the array with SetData() that matters. I didn't notice that before.

cklester · Nov 29, 2021

emexes said:
Try 8 table columns with:

B4X:

Private newrow(8) As String

Ah! That must be it.

As long as the array is of sufficient size, it doesn't matter what you put into it.

Thank you!

cklester · Nov 29, 2021

I wonder, then, if an error message should be produced when trying to use SetData() with a list of arrays that aren't enough.

B4J Question B4XTable Crashes with 8 Columns But Not With 7

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