CODEWITHSUNDEEP
javacomboboxdefaultreset
user3600952
user3600952

Reputation:

Resetting a combobox to the first item

I've created and populated a combobox by querying a database. When I have performed a few other functions in the program, I want to reset the combobox to the original value, i.e. a blank space. When I do this, I get an exception being thrown by the program.

The code is as follows:

to create the combo box: 

    tableNumberJComboBox = new JComboBox(); 
    tableNumberJComboBox.setBounds( 168, 26, 80, 20 );        
    tableNumberJComboBox.setFont(new Font("Serif", Font.PLAIN, 12)); 
    tableNumberJComboBox.addItem("");
    waiterJPanel.add(tableNumberJComboBox);

and then to populate it: 

private void loadTableNumbers()
{
    try 
    {   
        myStatement = null; 
        myResultSet = null; 
        myStatement = myConnection.createStatement(); 

        myResultSet = myStatement.executeQuery("SELECT tableNumber FROM restauranttables");
        while (myResultSet.next()) 
        {
            tableNumberJComboBox.addItem(myResultSet.getInt(1));
        }
        myResultSet.close(); 
    }
    catch(SQLException sqlexception) 
    {
        sqlexception.printStackTrace(); 
    }
} // end method loadTableNumbers

and then to reset the table number to a blank space: 

    tableNumberJComboBox.setSelectedItem("");

and the exception is:

Exception in thread "AWT-EventQueue-0" java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Integer

I've tried setSelectedItem(0), but this didnt work. How do I set this back to the original white space?

Thanks in advance.

Upvotes: 0

Views: 6403

Answers (3)

Milton
Milton

Reputation: 1

I faced the same problem, you could use:

tableNumberJComboBox.getSelectionModel().select(-1);

In my case (JavaFX), it helped!!! Hope it will help you too...

Upvotes: 0

camickr
camickr

Reputation: 324118

Don't create a new JComboBox, just use the existing combo box an reload the data:

Maybe something like:

tableNumberJComboBox.removeAllItems();
loadTableNumbers();

Edit:

The above suggestion works fine for me:

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class SSCCE extends JPanel
{
    private JComboBox<Integer> comboBox = new JComboBox<Integer>();
    private int value = 10;

    public SSCCE()
    {
        add( comboBox );
        addItems();

        JButton reset = new JButton( "Reset" );
        reset.addActionListener( new ActionListener()
        {
            public void actionPerformed(ActionEvent e)
            {
                comboBox.removeAllItems();
                addItems();
            }
        });
        add( reset );
    }

    private void addItems()
    {
        for (int i = 0; i < 5; i++)
            comboBox.addItem( new Integer(value++) );
    }

    private static void createAndShowUI()
    {
        JLabel label = new JLabel(new ImageIcon("mong.jpg"));

        JFrame frame = new JFrame("SSCCE");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add( new SSCCE() );
        frame.setLocationByPlatform( true );
        frame.pack();
        frame.setVisible( true );
    }

    public static void main(String[] args)
    {
        EventQueue.invokeLater(new Runnable()
        {
            public void run()
            {
                createAndShowUI();
            }
        });
    }
}

If this doesn't help then post a proper SSCCE of your own. And we don't have access to your database so you SSCCE should not include the database logic.

Upvotes: 0

TheTechWolf
TheTechWolf

Reputation: 2144

You could use tableNumberJComboBox.setSelectedItem(-1); , if white space means that you did not selected anything. Is that what you wish to do?

Upvotes: 1

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