本章目标;JLabel(标签);JLabel常用方法;JButton(按钮);JTextField(文本框);JTextArea(文本区域);JPasswordField(密码框) ;JCheckBox（复选框）;JRadioButton（单选按钮）;组合框JComboBox;组合框JComboBox—事件;public class Test4 extends JFrame implements ActionListener {
String[] items = { "篮球", "足球", "乒乓球" };
JComboBox<String> box = new JComboBox<String>(items);
Test4() {
box.addItem("排球");
this.setLayout(new FlowLayout());
this.add(box);
box.addActionListener(this);
}
public static void main(String[] args) {
new Test4().setVisible(true);
}
public
