Passar o item de um combo como parÂmetro

import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JFrame;
import javax.swing.JComboBox;
import java.awt.Rectangle;
import javax.swing.JButton;

public class TesteCombo extends JFrame {

	private static final long serialVersionUID = 1L;

	private JPanel jContentPane = null;

	private JComboBox jComboBox = null;

	private JButton jButton = null;

	/**
	 * This is the default constructor
	 */
	public TesteCombo() {
		super();
		initialize();
	}

	/**
	 * This method initializes this
	 * 
	 * @return void
	 */
	private void initialize() {
		this.setSize(300, 200);
		this.setContentPane(getJContentPane());
		this.setTitle("JFrame");
	}

	/**
	 * This method initializes jContentPane
	 * 
	 * @return javax.swing.JPanel
	 */
	private JPanel getJContentPane() {
		if (jContentPane == null) {
			jContentPane = new JPanel();
			jContentPane.setLayout(null);
			jContentPane.add(getJComboBox(), null);
			jContentPane.add(getJButton(), null);
		}
		return jContentPane;
	}

	/**
	 * This method initializes jComboBox	
	 * 	
	 * @return javax.swing.JComboBox	
	 */
	private JComboBox getJComboBox() {
		if (jComboBox == null) {
			jComboBox = new JComboBox();
			jComboBox.setBounds(new Rectangle(33, 57, 230, 30));
			toFillJComboBox();
		}
		return jComboBox;
	}
	
	private void toFillJComboBox(){
		
		getJComboBox().addItem("Teste 1");
		getJComboBox().addItem("Teste 2");
		getJComboBox().addItem("Teste 3");
		getJComboBox().addItem("Teste 4");
		getJComboBox().addItem("Teste 5");
		getJComboBox().addItem("Teste 6");
		
	}
	
	/**
	 * This method initializes jButton	
	 * 	
	 * @return javax.swing.JButton	
	 */
	private JButton getJButton() {
		if (jButton == null) {
			jButton = new JButton();
			jButton.setBounds(new Rectangle(94, 116, 96, 35));
			jButton.setText("Item");
			jButton.addActionListener(new java.awt.event.ActionListener() {
				public void actionPerformed(java.awt.event.ActionEvent e) {

					JOptionPane.showMessageDialog(null, getJComboBox().getSelectedItem());
					
				}
			});
		}
		return jButton;
	}

	public static void main(String args[]){
		
		TesteCombo testeCombo = new TesteCombo();
		testeCombo.setVisible(true);
		testeCombo.setDefaultCloseOperation(EXIT_ON_CLOSE);
	}

}