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EndUpdate

procedure EndUpdate;

Example​

procedure AddPairSafely(const Items: TStringList);
begin
  Items.BeginUpdate;
  try
    Items.Add('Code=100');
  finally
    Items.EndUpdate;
  end;
end;

Usage​

EndUpdate ends one TStrings update level and emits the string list's final update transition when the nesting count reaches zero.

  • Never call it speculatively. Pair it structurally in finally after a successful begin.
  • An exception from the final change event propagates with the count already zero.
  • Ending a batch does not commit or validate the mutations made within it.

Additional Technical Info​

EndUpdate is declared by hidden ancestor TStrings and is normally used through a concrete visible descendant such as TStringList. It must be called exactly once for each successful BeginUpdate.

Source-backed behaviour​

The installed RTL decrements the internal counter first. If the result is zero it calls virtual SetUpdateState(False); TStringList uses that transition to issue its final changed notification.

There is no balance guard. Calling EndUpdate at zero makes the count -1; later BeginUpdate sees a nonzero count, skips entry notification and increments back to zero, leaving the list outside the normal state sequence. Further mismatches can suppress notifications indefinitely.

BeginUpdate starts the nesting level. AddStrings, Exchange and Move already balance their own internal batches.

Official RTL references​

Created 2026-07-15