Java编译器使用JComboBox发出"未经检查或不安全的操作"警告

Question

基本上我是一个相当开始的Java学生,我必须创建一个包含JComboBox的简单GUI.该窗口看起来像这样:http://i.imgur.com/Jg7j4XD.jpg

当我编译代码(如下所示)时,它确实编译但我在jGRASP中收到以下警告:

Note: Lab6.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.

这是我的代码.我知道这意味着我必须指定涉及数据类型的东西(对吗？)但我认为我已经指定了足够的东西.感谢任何能提供帮助的人.

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

public class Lab6 extends JFrame
{
    private String[] choices = {"Hello", "Good-Bye"};

    public Lab6()
    {
        super("218 Lab 6");
        setSize(450,200);
        setVisible(true);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        setLayout(new BorderLayout());

        JPanel panelNorth = new JPanel();
            panelNorth.add(new JLabel("Welcome Class 218!"));

            JComboBox comboBox = new JComboBox(choices);
            panelNorth.add(comboBox);

            add(panelNorth,BorderLayout.NORTH);
    }

    public static void main(String[] args)
    {
        new Lab6();
    }
}

Answer 1

从Java 7开始,JComboBox需要泛型来描述它所拥有的数据:

JComboBox<String> comboBox = new JComboBox<>(choices);

不指定这些将产生显示的编译器警告.