如何在jComboBox中检索绑定到数据库表中的对象并将其存储到另一个表

Question

I had created a table named "model" and "item" in my database. And created classes Model() and Item(). For table "model", it has the following fields :model_ID and model_description. For table "item" : item_ID, item_description, model_ID.

Through binding the table "model" and jComboBox using Netbeans 8.2, I was able to display the model_description in jComboBox.

Now what I want to do is to store the selected item in jComboBox into my "item" table.

I have tried this code:

Session session = NewHibernateUtil.getSessionFactory.openSession();
Transaction transaction = session.beginTransaction();
Model model = (Model) session.get(Model.class, jComboBox.getSelectedIndex+1);
Item item = new Item();
item.setDescription(description);
item.setModel(model);
session.save(item);
transaction.commit();
session.close();

The problem of this code is that what if I will sort the display of model_description in my jComboBox in ascending/descending order, it will not return the right object.

Is there any way to store directly as model object the selected item in jComboBox?

Thank you for help!

Answer 1

Through binding the table "model" and jComboBox using Netbeans 8.2, I was able to display the model_description in jComboBox.

I have no idea what the Netbeans binding does, but that doesn't seem to be a good solution to me. What if you ever move from the Netbeans platform how will your code work or how will you be able to do this in the future?

Instead I would suggest you can store a custom object in the JComboBox. So you can store your Item object in the combo box and then create a custom renderer to display the "description" in the combo box.

The when you want the seledcted item you just use:

comboBox.getSelectedItem() 

and you have access to your Item object an all its properties.

A custom renderer would look something like:

class FooRenderer extends BasicComboBoxRenderer
{
    public Component getListCellRendererComponent(
        JList list, Object value, int index, boolean isSelected, boolean cellHasFocus)
    {
        super.getListCellRendererComponent(list, value, index, isSelected, cellHasFocus);

        if (value instanceof Foo)
        {
            Foo foo = (Foo)value;
            setText( foo.getDescription() );
        }

        return this;
    }
}

Replace the "Foo" object with your "Item" object.

However, when you use a custom renderer you will break the combo box as you will no longer be able to select the item using the keyboard by typing the first character of the item description. See Combo Box With Custom Renderer for more information on this problem and a solution.