Netbeans Combobox

[Bartosz Emas]

Hello All ! I am designing a very simple program in Netbeans. What I wish to achieve is when I select item from a Jcombobox for example, Item 1, in a JtextField will appear an integer. Is there any simple way to achieve this ? thank you for any response.

[Campbell Ritchie]

Welcome to the Ranch

Have you been through the Java Tutorials? About 11 pages down, you will find a page about combo boxes.

[Bartosz Emas]

I have went through it, however I did not find appropriate solution. Thank you for quick respond!!

[Campbell Ritchie]

It is exactly the same whether you use NetBeans, text editors, or whatever.

final JComboBox<Integer> combo = new JComboBox<Integer>(new Integer[]{1, 2, 3, 4});
...
final JTextArea textArea = ...;
...
combo.addActionListener(new ActionListener()
{
@Override actionPerformed(ActionEvent ev)
{
textArea.setText(combo.getSelectedItem().toString());
}
});

Note that a combo box implements ActionListener itself, but the API says not to use its own action performed method,

[Bartosz Emas]

I have created in NetBeans JForm and appended a few jComboBoxes and jTextFields. I have found the following code on the internet:

import java.awt.FlowLayout;
import java.awt.event.*;
import javax.swing.*;
public class MyWind extends JFrame{
public MyWind() {
initialize();
}
private void initialize() {
setSize(300, 300);
setLayout(new FlowLayout(FlowLayout.LEFT));
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
final JTextField field = new JTextField();
field.setSize(200, 50);
field.setText(" ");
JComboBox comboBox = new JComboBox();
comboBox.setEditable(true);
comboBox.addItem("item1");
comboBox.addItem("item2");
//
// Create an ActionListener for the JComboBox component.
//
comboBox.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent event) {
//
// Get the source of the component, which is our combo
// box.
//
JComboBox comboBox = (JComboBox) event.getSource();
Object selected = comboBox.getSelectedItem();
if(selected.toString().equals("item1"))
field.setText("30");
else if(selected.toString().equals("item2"))
field.setText("40");
}
});
getContentPane().add(comboBox);
getContentPane().add(field);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
new MyWind().setVisible(true);
}
});
}
}

However when I am typing into my program it does not work.

Any idea where this code should go ?

[Campbell Ritchie]

Yes, I can tell you where that code should go: recycle bin
Always tell us where you get code or quotes from, in case there is a copyright problem or similar. Always use code tags, which I have added for you, and you can see how much better it looks

I don't think flow layout is any good. I also don't like extending frames; that creates a class which tries to combine display (=V in MVC) and data (M) in one class. Did you notice the non‑OO design in the Listener? A load of if‑elses which will cease to work correctly if you add "item3" to the combo box, or write anything else not it is editable. And the assumption that the source is a combo box. It may be very old code; it has not been necessary to use getContentPane().add(...) for over 9 years. You can simply write add(...).

Please tell us what is going wrong. When I executed the code you posted, it put 30 or 40 in the text field, but failed to do anything when I edited the combo box, which is exactly what I would have expected. The code I posted yesterday would have put 1 2 3 or 4 in the text area if you had expanded it to a full class.