CODEWITHSUNDEEP
javaswingcombobox
fucorogu
fucorogu

Reputation: 43

JComboBox ActionListener doesn't work

I'd like to get back every second elements of an array (so in this case 2. and 4.). 

import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;


public class tester2 extends JFrame{
    /**
     * 
     */
    private static final long serialVersionUID = 1L;

    JFrame f = new JFrame();
    String [] corps = {"IBM", "Apple", "Oracle", "Google"};
    JComboBox <String> cb = new JComboBox <> ();

    JLabel l1 = new JLabel();

    public tester2() {
        f.setSize(500, 300);
        f.setLayout(new BorderLayout());
        f.setVisible(true);
        f.setTitle("Tester 2");
        f.setLocationRelativeTo(null);

        f.add(cb, BorderLayout.NORTH);
        f.add(l1);

        // Combo
        cb.removeAllItems();
        cb.addActionListener(new ActionListener() {

            public void actionPerformed(ActionEvent e) {
                for (int i = 1; i < corps.length; i=+2) {
                     String tempRes = corps[i];
                     System.out.println(tempRes);
                     cb.addItem(tempRes);
                }

            }
        });


    }


    public static void main(String[] args) {  
        new tester2();  
    } 
}

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Thanks

Upvotes: 0

Views: 1562

Answers (1)

Arnaud
Arnaud

Reputation: 17534

You aren't seeing anything because ActionEvent for a JComboBox is only fired when an item is selected.

Since your combobox is empty, this doesn't happen.

You could put a default value so that your ActionListener gets called.

Also it is probably better to put removeAllItems() in the actionPerformed method, so that you clear the combobox just before populating it .

One last note : the change from i = +2 to i += 2, because i = +2 means i=2, and you go into an infinite loop with index 2 .

    // Combo
    cb.addItem("--filler--");

    cb.addActionListener(new ActionListener() {

        public void actionPerformed(final ActionEvent e) {

            cb.removeAllItems();

            for (int i = 1; i < corps.length; i += 2) {
                String tempRes = corps[i];
                System.out.println(tempRes);
                cb.addItem(tempRes);
            }

        }
    });

Upvotes: 2

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