Test

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

import javax.swing.DefaultComboBoxModel;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JTextField;

public class Test {

    private JFrame frame;
    private JTextField textField;

    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    Test window = new Test();
                    window.frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    /**
     * Create the application.
     */
    public Test() {
        initialize();
    }

    /**
     * Initialize the contents of the frame.
     */
    private void initialize() {
        frame = new JFrame();
        frame.setBounds(100, 100, 450, 300);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        String[][] items = {{"alias1", "select1..."}, {"alias2", "select2..."}, {"alias3", "select3..."}};
        String[] alias = new String[items.length];
        String[] select = new String[items.length];
        JComboBox comboBox = new JComboBox();
        comboBox.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                int i = comboBox.getSelectedIndex();
                textField.setText(select[i]);
//              System.out.println(select[i]);
            }
        });

        for (int i = 0; i < items.length; i++) {
            alias[i] = items[i][0];
        }

        for (int i = 0; i < items.length; i++) {
            select[i] = items[i][1];
        }

        comboBox.setModel(new DefaultComboBoxModel(alias));
        frame.getContentPane().add(comboBox, BorderLayout.CENTER);

        textField = new JTextField();
        frame.getContentPane().add(textField, BorderLayout.SOUTH);
        textField.setColumns(10);
    }

}