Java JComboBox错误

我试图从Liang编写的“Java编程入门第9版”中编译以下程序。我在以下关于JComboBox的示例中发现一个错误：

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);
     }
}

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

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这是一个警告而不是错误。您缺少Java 1.7中引入的预期泛型类型。没有它，每次从

ComboBoxModel

将

字符串

类型添加到声明中以匹配模型数据

JComboBox<String> jcboColor = new JComboBox<>(new String[] { ... });

JComboBox jcboColor=newjcombobox（新字符串[]{…}）；

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阅读这篇来自泛型常见问题解答的有趣文章，到目前为止，Oracle的Swing教程中包含以下内容：

运行此命令会导致以下行抛出此警告：

JComboBox cb = new JComboBox(comboBoxItems);

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可能是因为代码自2008年以来就没有更新过？此解决方案帮助我清理了警告并顺利编译，因此值得称赞。

这是一个警告，不是错误，因为

imageComboBox=new JComboBox（names）；

再次运行该程序，它将正常工作

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您确定有错误吗？听起来像是关于类型安全的警告。如果确实是这样，那么您可以使用@SuppressWarnings（“未选中”），如下所述：