Question

I have the following structure in my UI

    <ScrollView
        android:id="@+id/vscroll"
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <TableLayout
            android:id="@+id/table"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" >
        </TableLayout>

    </ScrollView>

I fill the TableLayout with TableRows programmatically.

Sometimes I need to add rows at the top of the table (insert before child(0)).
And the problem is the ScrollView jumps up.
I can tell you that I Logged the ScrollY() position of the ScrollView before and after the row insertion. And it remains the same (!!)

This is what is causing the jump, because now I have some more rows and scroll position Y= 234 (for example) before was on row A and now the same position Y means row Q.

Row A was the (lt’s say) fifth row, and now after insertion row Q is the fifth row
So you see, from the ScrollView point of view nothing changed, but the View shows now a different Row.

If at this point you are not totally confused with my explanation, then maybe you can advise how can I insert rows at the top without changing what I see on screen.
In other words I want the insertion to go stealth without any influence on what the user sees.

If some code will help clear the picture, here is how I insert 5 rows at the top

table = (TableLayout) findViewById(R.id.table);
TableRow.LayoutParams params = new TableRow.LayoutParams(TableRow.LayoutParams.MATCH_PARENT, TableRow.LayoutParams.WRAP_CONTENT);
for(int i=0; i<5 ; i++) {   
    TableRow mr = new TableRow(getContext());
    // some stuff to set the row texts
    table.addView(mr, 0, params);
}

Before Insertion    After Insertion
Row 0               New Row 0
Row 1               New Row 1
Row 2               New Row 2
Row 3               New Row 3        <--- vscroll Y position stays the same
Row 4               New Row 4
Row 5               Old Row 0
Row 6               Old Row 1
Row 7               Old Row 2
Row 8               Old Row 3        (vscroll jumps up from here to new Row 3)
Row 9               Old Row 4
Row 10              Old Row 5
Row 11              Old Row 6

Answer 1

I haven’t tested it but you could try to post() a Runnable where you would get the newly inserted row’s height and then scroll the ScrollView by that amount so it stays at the same position:

final TableRow newRow = new TableRow(this);
        // add stuff to the row     
        tl.addView(newRow, 0, params);
        // sv is your ScrollView vscroll
        sv.post(new Runnable() {

            @Override
            public void run() {             
                int size = newRow.getHeight();              
                sv.scrollBy(0, size);
            }

        });