Question

I need to create an application where I need to get a user input from a radio button and then use the selected filename in a different class.I’m not sure how to implement this, beacuse everytime I try to place a getString() method in the MyAction class it gives me a null value. thanks!!

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.io.File;

public class SelectRadioButton{

    public SelectRadioButton(){

      // Directory path here
      String path = "W:\\materials"; 

      JFrame frame = new JFrame("Material Selection");
      JPanel panel = new JPanel(new GridLayout(0, 4));
      ButtonGroup bg = new ButtonGroup();

      String files;
      File folder = new File(path);
      File[] listOfFiles = folder.listFiles(); 
      JRadioButton  first;

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

       if (listOfFiles[i].isFile()) 
       {
       files = listOfFiles[i].getName();
           if (files.endsWith(".mtl") || files.endsWith(".MTL"))
           {

              first = new JRadioButton(files);
              panel.add(first,BorderLayout.CENTER);
              panel.revalidate(); 

              bg.add(first);
              first.addActionListener(new MyAction);
            }
         }
      }

       frame.add(panel, BorderLayout.NORTH);
       frame.getContentPane().add(new JScrollPane(panel), BorderLayout.CENTER);
       frame.setSize(1000, 400);
       frame.setVisible(true);
       frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
   }

  public class MyAction implements ActionListener{
        //String m;
      public void actionPerformed(ActionEvent e){
      String m =e.getActionCommand();
      String[] split = m.split("\\.");
      m=split[0];
      JOptionPane.showMessageDialog(null,"Your Selection is"+m+" radio button.");
   }
        /*
        public String getString(){
               return m;
        }
        */
   }
 }

Answer 1

Obviously, the m variable only will be set when the specific radio button receive a click event.
If you don’t want to change your code so much, do something like this:

public class MyAction implements ActionListener{
    String m;

    public MyAction(String radioButtonLabel){
        m = radioButtonLabel;
    }
    public void actionPerformed(ActionEvent e){
        JOptionPane.showMessageDialog(null,
                "Your Selection is"+m+" radio button.");
    }
    public String getString(){
        return m;
    }
}

And replace the:

first.addActionListener(new MyAction());

by:

first.addActionListener(new MyAction(files));

And improve the names of your variables… it is a little bit confusing!
Hope it helps.

UPDATE

To get the selected radio button:

public static JRadioButton getSelection(ButtonGroup group) {
    for (Enumeration e = group.getElements(); e.hasMoreElements();) {
        JRadioButton b = (JRadioButton) e.nextElement();
        if (b.getModel() == group.getSelection()) {
            return b;
        }
    }
    return null;
}