How to create JOptionPane with multiple list selections and extract all the choices?

Question

I am interested in creating a JOptionPane or any interactable pop-up Pane that contains multiple list selections. I also wish to extract the selections the user made.

The code below shows an MRE where I generate two different JOptionPanes with list selections and extract the choice from each. Essentially, I am trying to combine the two.

import javax.swing.JFrame;
import javax.swing.JOptionPane;

public class JOptionPaneTest {

  public static void main(String[] a) {
    
    JFrame frame = new JFrame();
    String bigList[] = new String[30];
    String smallList[] = new String[5];
    

    for (int i = 0; i < bigList.length; i++) {
      bigList[i] = Integer.toString(i);
    }
    
    for (int i = 0; i < smallList.length; i++) {
      smallList[i] = Integer.toString(i);
    }

    String choice = (String) JOptionPane.showInputDialog(frame, "Pick the first number", "Number 1", JOptionPane.QUESTION_MESSAGE,
        null, bigList, "Titan");
    
    String choice2 = (String) JOptionPane.showInputDialog(frame, "Pick the second number", "Number 2", JOptionPane.QUESTION_MESSAGE,
        null, smallList, "Titan");
    
    System.out.println(choice);
    System.out.println(choice2);

  }

}

What one of them looks like:

Answer 1

JOptionPane is actually very flexible. You could build a container containing any number of components and then use JOptionPane to display it, for example...

import java.awt.EventQueue;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import javax.swing.DefaultComboBoxModel;
import javax.swing.JComboBox;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;

public class Test {

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

    public Test() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                String bigList[] = new String[30];
                String smallList[] = new String[5];

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

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

                JComboBox<String> bigListComboBox = new JComboBox<>(new DefaultComboBoxModel<String>(bigList));
                JComboBox<String> smallListComboBox = new JComboBox<>(new DefaultComboBoxModel<String>(smallList));

                JPanel panel = new JPanel(new GridBagLayout());
                GridBagConstraints gbc = new GridBagConstraints();
                gbc.gridx = 0;
                gbc.gridy = 0;
                gbc.anchor = GridBagConstraints.LINE_END;
                gbc.insets = new Insets(4, 4, 4, 4);
                panel.add(new JLabel("Pick the first number"), gbc);
                gbc.gridy++;
                panel.add(new JLabel("Pick the second number"), gbc);

                gbc.gridx++;
                gbc.gridy = 0;
                gbc.anchor = GridBagConstraints.LINE_START;
                panel.add(bigListComboBox, gbc);
                gbc.gridy++;
                panel.add(smallListComboBox, gbc);

                JOptionPane.showMessageDialog(null, panel, "Pick two numbers", JOptionPane.QUESTION_MESSAGE);

                System.out.println("First number = " + bigListComboBox.getSelectedItem());
                System.out.println("Second number = " + smallListComboBox.getSelectedItem());
            }
        });
    }
}