我正在尝试从 Liang 的“Java 编程简介第 9 版”中编译以下程序。以下关于 JComboBox 的示例出现错误：
import javax.swing.*;
public class GUIComponents
{
public static void main (String[] args)
{
JButton jbtOK = new JButton ("OK"); // Creates a button with test OK
JButton jbtCancel = new JButton ("Cancel"); // Creats a cancel button
JLabel jlblName = new JLabel ("Enter your name: "); // Creates a label with the respective text
JTextField jtfName = new JTextField ("Type Name Here"); // Creates a text field with the respective text
JCheckBox jchkBold = new JCheckBox ("Bold"); // Creates a check boc wth the text bold
JCheckBox jchkItalic = new JCheckBox ("Italic");
JRadioButton jrbYellow = new JRadioButton ("Yellow"); // Creates a radio button with text Yellow
JRadioButton jrbRed = new JRadioButton ("Red"); // Creates a radio Button with text Red
**JComboBox jcboColor = new JComboBox (new String[] {"Freshman", "Sophomore", "Junior", "Senior"});**
JPanel panel = new JPanel (); // Creates a panel to group components
panel.add (jbtOK); // Add the OK button to the panel
panel.add (jbtCancel); // Add the Cancel button to the panel
panel.add (jlblName); // Add the lable to the panel
panel.add (jtfName);
panel.add (jchkBold);
panel.add (jchkItalic);
panel.add (jrbRed);
panel.add (jrbYellow);
panel.add (jcboColor);
JFrame frame = new JFrame ();
frame.add (panel);
frame.setTitle ("Show GUI Components");
frame.setSize (450,100);
frame.setLocation (200, 100);
frame.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);
frame.setVisible (true);
}
}
正在产生的错误是：
warning: [unchecked] unchecked call to JComboBox(E[]) as a member of the raw type JComboBox
JcomboBox jcboColor = new JComboBox(new String[] {"Freshman", "Sophomore", "Junior", "Senior"});
Where E is a time-variable:
E extends Object Declared in class JComboBox
