JAVA使用了未经检查或不安全操作

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

public class TickeWindow extends JFrame
{
JComboBox comBox,comBox1,comBox2; //下拉
JButton button_check,sale1,sale2,exit; //按钮
JTextArea area; //文本区
JTextField text1,text2; //文本框
JLabel title;

public TickeWindow()
{
    init();
    setVisible(true);
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}

void init()
{
    setLayout(new FlowLayout());
    title = new JLabel("网上售票系统");
    title.setSize(20,20);
    add(title);
    add(new JLabel("选择路线"));
    comBox = new JComboBox();
    comBox.addItem("和平->广州");
    comBox.addItem("广州->江门");
    comBox.addItem("江门->广州");
    comBox.addItem("广州->和平");
    add(comBox);
    button_check = new JButton("查询");
    add(button_check);
    area = new JTextArea(5,4);
    add(new JScrollPane(area));
    add(new JLabel("班次"));
    comBox1 = new JComboBox();
    comBox1.addItem("2001");
    comBox1.addItem("2002");
    comBox1.addItem("2003");
    comBox1.addItem("2004");
    add(new JLabel("票数"));
    text1 = new JTextField(2);
    add(text1);
    sale1 = new JButton("1号窗购买");
    add(sale1);
    add(new JLabel("班次"));
    comBox2 = new JComboBox();
    comBox2.addItem("2001");
    comBox2.addItem("2002");
    comBox2.addItem("2003");
    comBox2.addItem("2004");
    add(new JLabel("票数"));
    text2 = new JTextField(2);
    add(text2);
    sale2 = new JButton("2号窗购买");
    add(sale2);
    exit = new JButton("退出");
    add(exit);
}

}
这段代码提示不安全操作

http://www.cnblogs.com/jianbo-su/p/5864198.html