JComboBox populated by string array(using for loop) not appearing

Question

I am trying to populate my JComboBox with numbers 25 to 50 and this is what I've done,

--at the variable declarations--

String[] val = new String[25];
JComboBox box1 = new JComboBox();

--and in the "main"--

for(int i=0; i==val.length; i++){
   val[i] = Integer.toString(i+25);
}

box1.setModel(new DefaultComboBoxModel(val));

but in the end, the JComboBox only displays blank 25 spaces but does not display the numbers that should be saved in the string array which is numbers 25 - 50. Please help.

score 4 · Answer 1 · answered Mar 12 '13 at 08:10

4

Try changing

for(int i=0; i==val.length; i++){

to

for(int i=0; i<val.length; i++){

answered Mar 12 '13 at 08:10

Matthew T. Staebler

4,756
19
21

score 2 · Answer 2 · answered Mar 12 '13 at 08:27

val[i] = Integer.toString(i+25);

use proper data type for JComboBox, use Integer for ComboBoxModel
for example (usage of Vector in code implemented in API simulating the same code for ComboBoxModel)

enter image description here

import java.awt.GridLayout;
import java.util.Vector;
import javax.swing.Icon;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;

public class ComboBoxIntegerModel {

    private JComboBox comboBoxDouble;
    private JComboBox comboBoxInteger;
    private JComboBox comboBoxBoolean;
    private JComboBox comboBoxIcon;
    private Vector<Double> doubleVector = new Vector<Double>();
    private Vector<Integer> integerVector = new Vector<Integer>();
    private Vector<Boolean> booleanVector = new Vector<Boolean>();
    private Vector<Icon> iconVector = new Vector<Icon>();
    private Icon icon1 = ((UIManager.getIcon("OptionPane.errorIcon")));
    private Icon icon2 = (UIManager.getIcon("OptionPane.informationIcon"));
    private Icon icon3 = (UIManager.getIcon("OptionPane.warningIcon"));
    private Icon icon4 = (UIManager.getIcon("OptionPane.questionIcon"));

    public ComboBoxIntegerModel() {
        doubleVector.addElement(1.001);
        doubleVector.addElement(10.00);
        doubleVector.addElement(0.95);
        doubleVector.addElement(4.2);
        comboBoxDouble = new JComboBox(doubleVector);
        integerVector.addElement(1);
        integerVector.addElement(2);
        integerVector.addElement(3);
        integerVector.addElement(4);
        comboBoxInteger = new JComboBox(integerVector);
        booleanVector.add(Boolean.TRUE);
        booleanVector.add(Boolean.FALSE);
        comboBoxBoolean = new JComboBox(booleanVector);
        iconVector.addElement(icon1);
        iconVector.addElement(icon2);
        iconVector.addElement(icon3);
        iconVector.addElement(icon4);
        comboBoxIcon = new JComboBox(iconVector);
        JFrame frame = new JFrame("");
        frame.setLayout(new GridLayout(2,2,5,5));
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(comboBoxDouble);
        frame.add(comboBoxInteger);
        frame.add(comboBoxBoolean);
        frame.add(comboBoxIcon);
        frame.setLocationRelativeTo(null);
        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                ComboBoxIntegerModel comboBoxModel = new ComboBoxIntegerModel();
            }
        });
    }
}

thank you very much it works. but I also wanted to do something like a JComboBox that displays at least a hundred years(elements) like 1950 - 2050, how can I do that without doing "vector.addElement()" one by one? of course, doing .addElement one by one is not recommended either way for long list of elements. — Malice Sloth, Mar 12 '13 at 09:20
maybe there isn't any reason to store data in array, put them directly to the ComboBoxModel, this model is the same array (prepared for GUI) for rest of Java application, [see possible short_cuts in comments by @MadProgrammer](http://stackoverflow.com/a/15355529/714968) — mKorbel, Mar 12 '13 at 09:24

JComboBox populated by string array(using for loop) not appearing

2 Answers2