Повторно заполнить модель JComboBox, сохранив текущий выбор. ⇐ JAVA

[Anonymous]

I am new to Java and Java Swing but it is what I inherited. I am trying to figure out the best way to keep a combobox up to date with a changing list. If the user has already selected an item and that item is still in the new list I want to keep it selected. The following code seems to work but I'm looking for suggestions o make it better, cleaner, etc. especially in the "done" method of the swing worker. Currently I am dealing with the combobox and the model (I thought the model alone would be enough).

In my example the list of cars will be the same first 4 and the last 5-7 are randomly added or removed.
class CBItem { private int id; private String description; public CBItem(int id, String description) { this.id = id; this.description = description; } public int getId() { return id; } public String getDescription() { return description; } @Override public String toString() { return description; } @Override public boolean equals(Object o) { boolean equal = true; if (!(o instanceof CBItem)) { equal = false; } else { CBItem other = (CBItem)o; equal = other.description.equals(this.description); } return equal; } } import java.awt.BorderLayout; import java.awt.EventQueue; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.util.ArrayList; import java.util.List; import java.util.Random; import javax.swing.DefaultComboBoxModel; import javax.swing.JComboBox; import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.SwingWorker; import javax.swing.Timer; public class JComboBoxFiller extends JFrame { private static final long serialVersionUID = 1L; JPanel pnlMain; DefaultComboBoxModel mdlCars = new DefaultComboBoxModel(); List lstCurrentCars = new ArrayList(); JComboBox cbxCars; final String[] arrCarNames = new String[] {"Audi", "BMW", "Chevrolet", "Dodge", "Ford", "Hyundai", "Jaguar"}; public JComboBoxFiller() { setTitle("ComboBox Filler Demo"); setBounds(100, 100, 400, 200); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); pnlMain = new JPanel(new BorderLayout()); setContentPane(pnlMain); cbxCars = new JComboBox(mdlCars); JPanel pnlCenter = new JPanel(); pnlCenter.add(cbxCars, BorderLayout.CENTER); pnlMain.add(pnlCenter, BorderLayout.CENTER); setVisible(true); // Every 5 seconds repopulate the list of cars Timer timer = new Timer(3000, new ActionListener() { @Override public void actionPerformed(ActionEvent e) { new RepopulateCarsWorker().execute(); } }); timer.start(); } // This will be called every 5 seconds. It populates a list of 4 to 7 cars (CBItems) // then updates the combobox (cbxCars) with the new values. // It needs to keep the current car selected (if one was and still exists) private class RepopulateCarsWorker extends SwingWorker { ArrayList lstNewCars = new ArrayList(); protected ArrayList doInBackground() { Random rand = new Random(); int lastCar = 4 + rand.nextInt(3); for (int c = 0; c < lastCar; c++) { lstNewCars.add(new CBItem(c, arrCarNames[c])); } return lstNewCars; } protected void done() { try { ArrayList lstNewCars = get(); // If list stayed the same, nothing to do if (lstNewCars.equals(lstCurrentCars)) { return; } // Save the current selection so it can be reselected CBItem cbCurrentSelection = (CBItem) mdlCars.getSelectedItem(); mdlCars.removeAllElements(); mdlCars.addAll(lstNewCars); // Reselect if there was a selected item and it still exists // Question: Why do I have to deal with the combobox? // I thought model would be enough... mdlCars.setSelectedItem(cbCurrentSelection); cbxCars.setSelectedIndex(mdlCars.getIndexOf(cbCurrentSelection)); // Update current list for next comparison lstCurrentCars = lstNewCars; } catch (Exception e) { e.printStackTrace(); } } } public static void main(String[] args) { EventQueue.invokeLater(new Runnable() { public void run() { try { JComboBoxFiller frame = new JComboBoxFiller(); frame.setVisible(true); } catch (Exception e) { e.printStackTrace(); } } }); } }

Источник: https://stackoverflow.com/questions/780 ... -selection