Icons not appearing in JComboBox and how to resize?

Question

The objective is to have images appear within the ComobBox.

When using ImageIcon and the basic calls all work except the icons are very large. Not sure if the combobox uses the icon to set the size and if that can be altered.

When using a custom class that extends ImageIcon, no icons appear which is the main objective to address.

import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.util.ArrayList;

import javax.swing.ImageIcon;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JPanel;


public class JComboBoxWithIcons  extends JFrame {

private static final long serialVersionUID = 1L;

private final ImageIcon ICON1a  = new ImageIcon("c:\\Downloads\\Images\\Image1.jpg");
private final ImageIcon ICON2a  = new ImageIcon("c:\\Downloads\\Images\\Image2.jpg");
private final ImageIcon ICON3a  = new ImageIcon("c:\\Downloads\\Images\\Image3.jpg");

private final MyImageIconObject ICON1b  = new MyImageIconObject("c:\\Downloads\\Images\\Image1.jpg");
private final MyImageIconObject ICON2b  = new MyImageIconObject("c:\\Downloads\\Images\\Image2.jpg");
private final MyImageIconObject ICON3b  = new MyImageIconObject("c:\\Downloads\\Images\\Image3.jpg");

private JComboBox comboBox1;
private JComboBox comboBox2;

private JPanel    topPanel;

public JComboBoxWithIcons () {}

public void createGUI(){

    setMinimumSize(new Dimension(400,400));
    setTitle("Demo");
    setLocation(200, 200);

    topPanel = new JPanel();
    getContentPane().add(topPanel, BorderLayout.CENTER);

    ArrayList<ImageIcon> iconsA = new ArrayList<ImageIcon>();
    iconsA.add(ICON1a); 
    iconsA.add(ICON2a); 
    iconsA.add(ICON3a);

    ArrayList<MyImageIconObject> iconsB = new ArrayList<MyImageIconObject>();
    iconsB.add(ICON1b); 
    iconsB.add(ICON2b); 
    iconsB.add(ICON3b);
    
    comboBox1 = new JComboBox();
    comboBox2 = new JComboBox();

    for(ImageIcon val : iconsA){
        comboBox1.addItem(val);
    }

    for(MyImageIconObject val : iconsB){
        comboBox2.addItem(val);
    }
    
    topPanel.add(comboBox1);
    topPanel.add(comboBox2);

    super.addWindowListener(new WindowAdapter() {           
        public void windowClosing(WindowEvent e) {              
            dispose();          
        }           
    }); 
}

public static void main(String[] args)  
{

    JComboBoxWithIcons T = new JComboBoxWithIcons();
    T.createGUI();
    T.setVisible(true);        
}


    class MyImageIconObject extends ImageIcon
    {
        float x;
        ImageIcon ic;
        public MyImageIconObject(String iconLocation)
        {
            this.ic = new ImageIcon(iconLocation); 
        }
    
        @Override
        public void paintIcon(Component c, Graphics g, int x, int y)
        {
            super.paintIcon(c, g, x, y);
//          Graphics2D g2d = (Graphics2D) g;
//          ic.paintIcon(c, g2d, x, y);
            System.out.println("Painting 2");
        }
    }
    
}

When the above code is executed, it produces the following :

The example creates 2 ComboBoxes with the same icons.

ComboBox1 - displays the icons, but they are large.

ComboBox2 - uses the custom class and overrides the paintIcon() as I plan to do additional modifications to the icons but first need them to appear.

Question 1 (more of a curiosity question) - to resize the icons will a renderer be required?

Question 2 (main objective) - for ComboBox 2, why are the icons not appearing?

score 1 · Accepted Answer · answered Sep 16 '20 at 12:23

1

Your MyImageIconObject class extends ImageIcon but you don't call the constructor of the parent class you just instantiate an ImageIcon object. So when you call the paintIcon method the parent class will have no idea about your ImageIcon object and refer to a null.

Here is an example how you can fix your icon not showing problem

class MyImageIconObject extends ImageIcon
    {
        float x;
        public MyImageIconObject(String iconLocation)
        {
            super(iconLocation); 
        }
    
        @Override
        public void paintIcon(Component c, Graphics g, int x, int y)
        {
            super.paintIcon(c, g, x, y);
//          Graphics2D g2d = (Graphics2D) g;
//          ic.paintIcon(c, g2d, x, y);
            System.out.println("Painting 2");
        }
    }

answered Sep 16 '20 at 12:23

Attila jáger

86
4

Thanks, adding that 1 line fixed it. With regards to the sizing issue, would that have to be addressed via a Renderer? – Unhandled Exception Sep 16 '20 at 12:31
I'm not sure exactly, but if you can you might be able to resize the image locally or use an approach like [this](https://stackoverflow.com/questions/6714045/how-to-resize-jlabel-imageicon) – Attila jáger Sep 16 '20 at 12:37
Try it with MSpaint. Change the resolution to the desired one. – Attila jáger Sep 16 '20 at 12:40
Thanks. I figured, it may be related to actual image size. Will research the code in the link. – Unhandled Exception Sep 16 '20 at 12:44

Icons not appearing in JComboBox and how to resize?

1 Answers1