C#：为什么当我在数据网格视图中按下删除按钮时，它没有从 arraylist 中删除数据？

Question

When I click the delete button in the datagridview, it deletes the row but does not delete the array list.

ArrayList sepet = new ArrayList();
ArrayList sepetisim = new ArrayList();
ArrayList sepetkg = new ArrayList();
ArrayList sepetfiyat = new ArrayList();

private void guna2DataGridView3_CellClick(object sender, DataGridViewCellEventArgs e) {
    if (e.ColumnIndex == 4) {
        //For Delete
        if (MessageBox.Show("Silmek İster misin", "Soru", MessageBoxButtons.YesNo, MessageBoxIcon.Question) == DialogResult.Yes) {
            
            foreach (DataGridViewRow row in guna2DataGridView3.SelectedRows) {
                guna2DataGridView3.Rows.RemoveAt(row.Index);
                sepet.Remove(guna2DataGridView3.Rows[e.RowIndex].Cells[0].Value);
                sepetisim.Remove(guna2DataGridView3.Rows[e.RowIndex].Cells[1].Value);
                sepetkg.Remove(guna2DataGridView1.Rows[e.RowIndex].Cells[2].Value);
                sepetfiyat.Remove(guna2DataGridView1.Rows[e.RowIndex].Cells[3].Value);
            }
        }
        return;
    }
}

Answer 1

ArrayList is a collection that's non-generic . The method Remove determine equality by calling object.equals , and it's a leaner operation O(N) if you want to constantly look things up by value I suggest using a different collection like HashSet or Dictionary , also, I'd use generic collection to avoid things like boxing it hurts the performance of the application and it introduces unnecessary memory allocations .

As to the issue in question, two possibilities:

1. You are removing the row and the trying to access its columns and removing their values that does not exists anymore
2. You are trying to remove not a primitive type, that a call object.equals becomes a reference comparison which is going to never be true.