JComboBox width

Question

I have created a jComboBox but it takes the full width of the frame. how to set the width fixed.

yes borderlayout for the frame and box layout for the panel. i am adding the code here:

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

public class Window8  {

    JFrame frame;
    JPanel panel;
    JComboBox combo;
    public void go(){

    String[] option = { "STUDENT", "TEACHER" };

    combo.setPreferredSize(new Dimension(1,25));
    combo = new JComboBox(option);
    menu.setSelectedIndex(0);

    frame = new JFrame("DELETION"); 
    frame.setLocationRelativeTo(null);
    frame.setSize(400, 300);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setVisible(true);

    panel = new JPanel();
    panel.setLayout(new BoxLayout(panel,BoxLayout.Y_AXIS));

    frame.getContentPane().add(BorderLayout.NORTH,panel);
    panel.add(combo);   
}

Sayre

i have added my code. please have a look at it. – Sayre

Reformatted code; copyedited; please revert if incorrect. – Anemochore

Answer 1

The width is automatically determined by the width of the largest item added to the combo box. You can control the display by using:

comboBox.setPrototypeDisplayValue("text here");

You might also consider using the Combo Box Popup to control the popup size.

Edit:

Since you added code that shows you are using a BoxLayout you can try the following:

comboBox.setMaximumSize( comboBox.getPreferredSize() );

Or you can do something like:

JPanel wrapper = new JPanel();
wrapper.add( comboBox );
panel.add( wrapper );

Read the section from the Swing tutorial on Using Layout Managers to understand how these suggestions work.

Korrie

Using setPrototypeDisplayValue with a sensitive option helps on properly resizing the JComboBox while allowing it to have a different size according to container definition. Thanks! – Fenrir

Answer 2

try comboBox.setPreferredWidth(200); or some other value to set the width

jzd is right. The actual API is setPreferredSize(new Dimension(...));

Gefell

i tried but gives this error. " The method setPreferredWidth(int) is undefined for the type JComboBox" – Sayre

Looking in the API, the exact method is: setPreferredSize(Dimension preferredSize) – Katlin

Answer 3

Use a different LayoutManager. Try FlowLayout.

Katlin

The width will be automatically determined based on the contents or use setPreferredSize() or camickr's suggestion. But if you put it in a layout that stretches it will not matter. – Katlin

Answer 4

Here is something you can do with box layout.

• Change axis to line axis, Add
• horizontal glue, Add rigid area,
• place the component

. code snippet below:

panel = new JPanel();
panel.setLayout(new BoxLayout(panel, BoxLayout.LINE_AXIS));
panel.add(Box.createHorizontalGlue());
panel.add(Box.createRigidArea(new Dimension(10, 0)));
panel.add(combo);
frame.getContentPane().add(BorderLayout.NORTH, panel);

Squinty

Answer 5

You might want to use setSize() method.

combo.setSize(200, combo.getPreferredSize().height);

Bloodstain

Answer 6

Don't use JCombobox<>() instead of that use Combobox<>() then width won't change, also if you set preferred size it won't change with Combobox so use this instead

Hildredhildreth

ComboBox is a heavyweight AWT component. AWT components and Swing components don't always play well together. – Gurgitation