好吧，就这么简单，无法实现单例模式，代码我网上找的，自己修改了下，具体的自己不太懂
求高人解答
- Java code
import java.awt.Color;import java.awt.event.ItemEvent;import java.awt.event.ItemListener;import java.util.HashMap;import java.util.Map;import javax.swing.JButton;import javax.swing.JCheckBox;import javax.swing.JComboBox;import javax.swing.JFrame;import javax.swing.JLabel;import javax.swing.JMenu;import javax.swing.JMenuBar;import javax.swing.JMenuItem;import javax.swing.JPanel;import javax.swing.JTextField;import javax.swing.border.TitledBorder;public class ColorTest extends JFrame implements ItemListener { private static final long serialVersionUID = 1L; //菜单栏 private JMenuBar menubar = new JMenuBar(); private JMenu fileMenu = new JMenu("基本信息设置"); private JMenuItem newMenuItem = new JMenuItem("客户信息设置"); private JMenuItem openMenuItem = new JMenuItem("货运方式设置"); private JMenuItem saveMenuItem = new JMenuItem("联系人设置"); private JMenuItem saveAsMenuItem = new JMenuItem("设备信息设置"); private JMenuItem exitMenuItem = new JMenuItem("员工管理"); private JMenuItem goodsStyle = new JMenuItem("货单类型"); private JMenuItem extraSetting = new JMenuItem("附件设置"); private JMenu configMenu = new JMenu("编辑打印报表"); private JMenuItem backgroudMusicMenu=new JMenuItem("编辑收发货单"); private JMenuItem backColorMenu = new JMenuItem("编辑维修单"); //第一个Jpanel里的内容 JLabel jl1=new JLabel("客户名称"); JCheckBox jcb1=new JCheckBox("查询"); //客户名称 JTextField jt=new JTextField(10); String str[]={"AAA","BBB","CCC"}; JComboBox JCB=new JComboBox(str); //客户地址 JLabel jl2=new JLabel("客户地址"); JTextField jf1=new JTextField(); //联系人 JLabel jl3=new JLabel("联系人"); String str2[]={"AAA","BBB","CCC"}; JComboBox JCB2=new JComboBox(str); //手机 JLabel jl4=new JLabel("手机"); JTextField jtf2=new JTextField(); //联系电话 JLabel jl5=new JLabel("联系电话"); JTextField jtf3=new JTextField(); //功能按钮 JButton jb1=new JButton("清空客户信息"); JButton jb2=new JButton("创建客户"); //单例模式代码 private static Map<String,ColorTest> map = new HashMap<String,ColorTest>(); static{ ColorTest single = new ColorTest(); map.put(single.getClass().getName(), single); } public static void main(String args[]) { try { ColorTest single3 = ColorTest.getInstance(null); } catch (Exception e) { e.printStackTrace(); } } /** * Create the frame */ /** * */protected ColorTest() { super("维修单收发货程序"); getContentPane().setLayout(null); setBounds(40, 40, 900, 660); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); final JPanel panel = new JPanel(); panel.setBorder(new TitledBorder(null, "客户信息", TitledBorder.DEFAULT_JUSTIFICATION, TitledBorder.DEFAULT_POSITION, null, Color.BLUE)); panel.setLayout(null); panel.setBounds(30, 25, 800, 155); getContentPane().add(panel); final JButton button = new JButton(); button.setBounds(84, 74, 106, 28); button.setText("New JButton"); //panel.add(button); //上面的Jpanel内容添加 jl1.setBounds(22,10,55,40); panel.add(jl1); jcb1.setBounds(85,10,55,40); panel.add(jcb1); //菜单栏添加代码 this.setJMenuBar(menubar); menubar.add(fileMenu); menubar.add(configMenu); fileMenu.add(newMenuItem); fileMenu.add(openMenuItem); fileMenu.add(saveMenuItem); fileMenu.add(saveAsMenuItem); fileMenu.add(exitMenuItem); fileMenu.add(goodsStyle); fileMenu.add(extraSetting); configMenu.add(backgroudMusicMenu); configMenu.add(backColorMenu); //下拉菜单1（JPanel） JCB.setMaximumRowCount(3); JCB.addItemListener(this); JCB.setLayout(null); JCB.setBounds(22,50,200,20); panel.add(JCB); //文本框1 jl2.setLayout(null); jl2.setBounds(260,10,53,43); panel.add(jl2); jf1.setLayout(null); jf1.setBounds(260,50,370,22); panel.add(jf1); //下拉菜单3 jl3.setLayout(null); jl3.setBounds(22,80,53,22); panel.add(jl3); JCB2.setMaximumRowCount(3); JCB2.addItemListener(this); JCB2.setLayout(null); JCB2.setBounds(22,110,198,20); panel.add(JCB2); //文本框2 jl4.setLayout(null); jl4.setBounds(260,70,50,50); panel.add(jl4); jtf2.setLayout(null); jtf2.setBounds(260,110,140,20); panel.add(jtf2); //文本框3 jl5.setLayout(null); jl5.setBounds(445,70,70,50); panel.add(jl5); jtf3.setLayout(null); jtf3.setBounds(445,110,185,20); panel.add(jtf3); //第一个JPanel的右边2个按钮 jb1.setLayout(null); jb1.setBounds(650,70,130,30); panel.add(jb1); this.setResizable(false); this.setVisible(true); }//单例模式代码public static ColorTest getInstance(String name) { if(name == null) { name = ColorTest.class.getName(); System.out.println("name == null"+"--->name="+name); } if(map.get(name) == null) { try { map.put(name, (ColorTest) Class.forName(name).newInstance()); } catch (InstantiationException e) { e.printStackTrace(); } catch (IllegalAccessException e) { e.printStackTrace(); } catch (ClassNotFoundException e) { e.printStackTrace(); } } return map.get(name); }@Overridepublic void itemStateChanged(ItemEvent e) { // TODO Auto-generated method stub }}