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

public class Exemplo0908 extends JFrame implements ActionListener,ItemListener
{
 JLabel l1;
 JTextField t1,t2,t3;
 JComboBox combo;
 JButton b1,b2,b3,b4,b5,b6,b7,b8;

 public static void main(String args[])
 {
  JFrame Janela = new Exemplo0908();
  Janela.show();
  WindowListener x = new WindowAdapter()
  { public void windowClosing(WindowEvent e) {System.exit(0); } };
  Janela.addWindowListener(x);
 }

 Exemplo0908()
 {
  setTitle("Uso do ComboBox");
  setSize(400,170);
  getContentPane().setBackground(new Color(190,190,190));
  l1 = new JLabel("Conteudo");
  l1.setForeground(Color.blue);
  l1.setFont(new Font("Arial",Font.BOLD,15));
  b1 = new JButton("Mostra Texto");
  b1.addActionListener(this);
  b2 = new JButton("Mostra Indice");
  b2.addActionListener(this);
  b3 = new JButton("Adiciona Item");
  b3.addActionListener(this);
  b4 = new JButton("Remove Item");
  b4.addActionListener(this);
  b5 = new JButton("Remove Todos");
  b5.addActionListener(this);
  b6 = new JButton("Quant.Itens");
  b6.addActionListener(this);
  t1 = new JTextField();
  t2 = new JTextField();
  String[] cores = {"Branco","Vermelho","Azul","Verde"};
  combo = new JComboBox(cores);
  combo.addItemListener(this);
  getContentPane().setLayout(new GridLayout(5,2));
  getContentPane().add(l1);
  getContentPane().add(combo);
  getContentPane().add(b1);
  getContentPane().add(b4);
  getContentPane().add(b2);
  getContentPane().add(b5);
  getContentPane().add(b3);
  getContentPane().add(t1);
  getContentPane().add(b6);
  getContentPane().add(t2);
 }

 public void actionPerformed(ActionEvent e)
 {
  if (e.getSource()==b1)
  { l1.setText("Texto: "+combo.getSelectedItem()); }
  if (e.getSource()==b2)
  { l1.setText("Indice: "+combo.getSelectedIndex()); }
  if (e.getSource()==b3)
  {
   if (t1.getText().length()!=0)
   {
    combo.addItem(t1.getText());
    t1.setText("");
   }
  }
  if (e.getSource()==b4)
   combo.removeItemAt(combo.getSelectedIndex());
  if (e.getSource()==b5)
   combo.removeAllItems();
  if (e.getSource()==b6)
   t2.setText(""+combo.getItemCount());
 }
 public void itemStateChanged(ItemEvent e)
 {
  t1.setText(""+combo.getSelectedItem());
 }
}