即使清除后，java ListView也会显示内容

Question

这是我的代码。我只想根据所选类别显示子类别。 但它只是改变了第一行。

public void refreshSubCategoryHandle(ActionEvent E) throws Exception {
        this.listSubCategories.getItems().clear();
        ObservableList<SubCategory> olsc = FXCollections.observableArrayList();
        olsc.clear();
        Connection con = (Connection) ConnectionClass.getConnection();
        String Sql = new String();
        Sql = "SELECT * FROM subCategory WHERE catId = '"+listCategories.getSelectionModel().getSelectedItem().getCatId()+"'";
        Statement st = (Statement) con.createStatement();
        ResultSet rst = st.executeQuery(Sql);
        while(rst.next()) {
            System.out.println("SubCateGory : "+rst.getString("sCatName"));
            olsc.add(new SubCategory(rst.getInt("sCatId"), rst.getInt("catId") , rst.getString("sCatName"), rst.getString("sCatDescription"), rst.getInt("sCatRank"), rst.getString("sCatCreatedAt"), rst.getString("sCatUpdatedAt"), rst.getString("sCatAddedBy")));
            //SubCategoryList.add(ct);
        }
//      System.out.println(olsc.get(1));
//      observableSubCategories.addAll(SubCategoryList);
        this.listSubCategories.getItems().addAll(olsc);
    }

每次触发此功能时，它只应在列表视图中显示类别为1的子类别，但它也会显示其他列表的数据...（旧数据）

问题：它不会替换整个旧数据，而只会替换列表视图中的1行旧数据。