如何在 jTable 顶部显示最后添加的行

Question

Hello I have a question I want to know if is there a way to display the last added row at the top of jTable in runtime I updated the select statement "SELECT * FROM table ORDER BY ID DESC" which fills my table but the recent added row show up at the bottom of the table till I close the program and I open it again then it shows up at the top

TableItemsModel:

public class TableItemsModel extends AbstractTableModel{
    
    ItemsDao itemDao = new ItemsDao();
    private List<Items> items;

    public TableItemsModel() throws Exception {
        this.items = (ArrayList<Items>)itemDao.getItemsList();
    }   
    
    private DateFormat df = new SimpleDateFormat("dd-MM-yyyy");
    
    @Override
    public int getRowCount() {
        return items.size();
    }

    @Override
    public int getColumnCount() {
        return 3;
    }

    @Override
    public Object getValueAt(int rowIndex, int columnIndex) {
        Items item = items.get(rowIndex);
        switch(columnIndex){

            case 0: return p.getProductName();
            case 1: return p.getProductCategory();
            case 2: return p.getProductPrice();
            default: return "";
                
        }
    }
    
    public String getColumnName(int column){
        switch(column){

            case 0: return "PRODUCT NAME";
            case 1: return "PRODUCT CATEGORY";
            case 2: return "PRICE";
            default: return "";
        }
    }
    
    public void addRow(Items item){
        items.add(item);
        fireTableRowsInserted(items.size()-1, items.size()-1);
    }
    
    public void deleteRow(Items item){
        items.remove(item);
        fireTableRowsInserted(items.size()-1, items.size()-1);
    }  
}

jFrame:

private final TableItemsModel model;

    public Products() throws Exception {

        this.model = new TableItemsModel();

 private void btnAddItemActionPerformed(java.awt.event.ActionEvent evt) {
    
        String productName = txtProductName.getText();
        String productCategory = txtProductCategory.getText();
        int productPrice = Integer.valueOf(txtPrice.getText());
        
        try {
            int count = ItemsDao.getInstance().insert(itemDao);
            if (count == 1) {
                model.addRow(Items);
    
                JOptionPane.showMessageDialog(null,"item successfully added");
            } else {
                JOptionPane.showMessageDialog(null, "Cannot Add Item");
            }
        } catch (Exception ex) {
            Logger.getLogger(AddNewPatient.class.getName()).log(Level.SEVERE, null, ex);
        }
   } 
}

Answer 1

First of all why are you calling your custom object Items . That is plural. Objects should be given the singular version of the name. So a better name would be Item or maybe even Product , since you use "product" in all you method names. Be consistent.

can you tell me how to include the method insertRow into my code please

You are using a List to hold the data. Read the List API and you will see that there are two add(...) methods. One method adds the element at the end of the List and the other method inserts the element at the specified index of the List .

So to add an Item at the beginning of the List you would specify 0 as the index.

To do this you copy the logic of your addRow(...) method except you want two parameters:

public void insertRow(int index, Item item)

Then you change the logic in the method to:

1. insert the Item at the specified index of the List.
2. invoke the fireTableRowsInserted(..) method at the specified index.

By passing in the index you make the method very flexible. You can insert an Item at the start or in the middle (if required).