I have a swing GUI with a JList inside a JScrollPane and I've populated it with Strings. I want to get the selected String from the list but everytime it returns -1. I had also made selection listeners which didn't work. Looked up other ones from posts here but the listener is never fired no matter how much I click. Single selection mode is selected. Here's the button method. Value is null, index is -1.
loadSongBtn.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
int index=list.getSelectedIndex();
System.out.println("test "+list.getSelectedValue());
String name=(String)list.getModel().getElementAt(index); //works if i put a number
}
});
Here's the initialization:
private void initList(){
String[] songNames = extractSongs();
JList songsList=new JList(songNames); //tried to see if the problem is here
this.list=songsList;
}
private void createUIComponents() {
initList();
songListPane = new JScrollPane(list);
list.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
}
Here's the SelectionListener just in case
list.addListSelectionListener(new ListSelectionListener() {
@Override
public void valueChanged(ListSelectionEvent e) {
if (!e.getValueIsAdjusting()) {
JList<String> lst = (JList<String>) e.getSource();
String selection = lst.getSelectedValue();
System.out.println(selection);//doesnt go into the method at all in debug
}
}
});
Putting everything together it's working, so you probably messed up some variables (maybe you initialize a JList and register listeners there, then overvrite it in method initList()). Here a working example:
package test;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.Box;
import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JList;
import javax.swing.JScrollPane;
import javax.swing.ListSelectionModel;
import javax.swing.event.ListSelectionEvent;
import javax.swing.event.ListSelectionListener;
public class TestJList {
protected JList<String> list;
protected JScrollPane songListPane;
protected JButton loadSongBtn;
private void initList(){
String[] songNames = new String[] { "abba", "dsst", "crvg" };
JList<String> songsList=new JList(songNames); //tried to see if the problem is here
this.list=songsList;
}
private void createUIComponents() {
initList();
loadSongBtn=new JButton("Load");
songListPane = new JScrollPane(list);
songListPane.setPreferredSize(new Dimension(200,400));
list.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
list.addListSelectionListener(new ListSelectionListener() {
@Override
public void valueChanged(ListSelectionEvent e) {
if (!e.getValueIsAdjusting()) {
JList<String> lst = (JList<String>) e.getSource();
String selection = lst.getSelectedValue();
System.out.println("SEL CHANGED "+selection);//doesnt go into the method at all in debug
}
}
});
loadSongBtn.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
int index=list.getSelectedIndex();
if (index<0) {
System.out.println("Nothing selected");
return;
}
System.out.println("BUTTON "+list.getSelectedValue());
String name=(String)list.getModel().getElementAt(index); //works if i put a number
}
});
}
public TestJList() {
initList();
createUIComponents();
JFrame frame=new JFrame("Test JList");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Box content=new Box(BoxLayout.Y_AXIS);
content.add(songListPane);
content.add(loadSongBtn);
frame.setContentPane(content);
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
new TestJList();
}
}