Erro na hora de preencher campos do comboBox

import java.awt.BorderLayout;
import java.awt.EventQueue;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javax.swing.JLabel;
import javax.swing.JTextField;
import java.awt.Font;
import javax.swing.JComboBox;
import javax.swing.DefaultComboBoxModel;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;


public class CadastroChamado extends JFrame {

	private JPanel contentPane;
	private JTextField textField;

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

	/**
	 * Create the frame.
	 */
	public CadastroChamado() {
		setTitle("Cadastro Chamados");
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		setBounds(100, 100, 450, 300);
		contentPane = new JPanel();
		contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
		setContentPane(contentPane);
		contentPane.setLayout(null);
		
		JLabel lblNewLabel = new JLabel("Solicitante:");
		lblNewLabel.setFont(new Font("Tahoma", Font.PLAIN, 11));
		lblNewLabel.setBounds(10, 54, 65, 14);
		contentPane.add(lblNewLabel);
		
		textField = new JTextField();
		textField.setFont(new Font("Tahoma", Font.PLAIN, 11));
		textField.setBounds(75, 52, 101, 17);
		contentPane.add(textField);
		textField.setColumns(10);
		
		JComboBox comboBox = new JComboBox();
		comboBox.setFont(new Font("Tahoma", Font.PLAIN, 11));
		comboBox.setBounds(10, 79, 304, 20);
		contentPane.add(comboBox);
		
		JComboBox comboBox_1 = new JComboBox();
		comboBox_1.setFont(new Font("Tahoma", Font.PLAIN, 11));
		comboBox_1.setModel(new DefaultComboBoxModel(new String[] {"-Produto-", "Service Desk"}));
		comboBox_1.setBounds(10, 110, 208, 20);
		contentPane.add(comboBox_1);
		
		final JComboBox comboBox_2 = new JComboBox();
		comboBox_2.setFont(new Font("Tahoma", Font.PLAIN, 11));
		comboBox_2.setModel(new DefaultComboBoxModel(new String[] {"-Selecione a Categoria-", "Infraestrutura", "Sistema", "Credencias de acessos"}));
		comboBox_2.setBounds(10, 141, 208, 20);
		contentPane.add(comboBox_2);
		
		JComboBox comboBox_3 = new JComboBox();
		comboBox_3.setFont(new Font("Tahoma", Font.PLAIN, 11));
		comboBox_3.setBounds(10, 172, 208, 20);
		contentPane.add(comboBox_3);
		
		
		comboBox_3.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				if(comboBox_2.getSelectedObjects().equals("Infraestrutura")){
					comboBox_3.setModel(new DefaultComboBoxModel(new String[] {"Clarity","Email","Instalação/ Configuração de HardWare","Instalação/ Atualização de Software","Manutenção de Hardware","Reserva de Equipamento","Servidor","Telefonia"}));
				}
			}
		});
		
		
	}
}