模擬時鐘與不同的時區

Question

我想建立一個模擬時鐘與不同的時區，但我收到錯誤。 我不知道我是否可以像我現在使用的方式使用我的iListener。我想通過更改當前時間的添加或減少來獲得不同的時區。可能嗎？ 這裏是我的代碼：

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

import java.util.Date; 

public class SimpleAnalogClock extends JPanel 
{ 

int centerPointX; 
int centerPointY; 

int xs; 
    int ys; 

Font quartzFont; 

Date currentDate; 
private JCheckBox Turkey, England; 

public SimpleAnalogClock() 
{ 
    setBackground(new Color(0,0,0)); 

    JFrame frame=new JFrame("Simple Analog Clock"); 
    Turkey = new JCheckBox("Turkey"); 
    England = new JCheckBox ("England"); 
    add(Turkey); 
    add(England); 
    iListener listener = new iListener(); 
    Turkey.addItemListener(listener); 
    England.addI 

    frame.add(this); 
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
    frame.setSize(450,450); 
    frame.setLocationRelativeTo(null); 
    frame.setVisible(true); 


    //LOOP THAT WILL UPDATE CLOCK 
    while(true) 
    { 
     repaint(); 
     try 
     { 
      Thread.sleep(900); 
     } 
     catch(Exception exception) 
     { 
      exception.printStackTrace(); 
     } 
    } 
} 

public iListener implements ItemListener 
{ 
    public void itemStateChanged (ItemEvent e) 
    { 
     if(Turkey.isSelected()) 
     { 
        /**Information that i mean here is 
      *coordinate for second pointer's corner. 
      *You can try change value 5 in xsm,ysm,xsa and ysa. 
      *After that, try compile and execute this program. 
      **/ 
      int s=currentDate.getSeconds(); 

      int s_minus_five=s-5; 
      int s_add_five=s+5; 

      xs = (int) (Math.cos(s * Math.PI/30 - Math.PI/2) * 170 + centerPointX); 
      ys = (int) (Math.sin(s * Math.PI/30 - Math.PI/2) * 170 + centerPointY); 

      int xsm=(int) (Math.cos(s_minus_five * Math.PI/30 - Math.PI/2) * 5 + centerPointX); 
      int ysm=(int) (Math.sin(s_minus_five * Math.PI/30 - Math.PI/2) * 5 + centerPointY); 

      int xsa=(int) (Math.cos(s_add_five * Math.PI/30 - Math.PI/2) * 5 + centerPointX); 
      int ysa=(int) (Math.sin(s_add_five * Math.PI/30 - Math.PI/2) * 5 + centerPointY); 
      //************GET CURRENT SECOND AND ALL INFORMATION TO DRAW SECOND POINTER************** 

      //************GET CURRENT MINUTE AND ALL INFORMATION TO DRAW MINUTE POINTER************** 
      /**Information that i mean here is 
      *coordinate for minute pointer's corner. 
      *You can try change value 10 in xmm,ymm,xma and yma. 
      *After that, try compile and execute this program. 
      **/ 
      int m=currentDate.getMinutes(); 

      int m_minus_ten=m-10; 
      int m_add_ten=m+10; 

      int xm = (int) (Math.cos(m * Math.PI/30 - Math.PI/2) * 170 + centerPointX); 
      int ym = (int) (Math.sin(m * Math.PI/30 - Math.PI/2) * 170 + centerPointY); 

      int xmm=(int) (Math.cos(m_minus_ten * Math.PI/30 - Math.PI/2) * 10 + centerPointX); 
      int ymm=(int) (Math.sin(m_minus_ten * Math.PI/30 - Math.PI/2) * 10 + centerPointY); 

      int xma=(int) (Math.cos(m_add_ten * Math.PI/30 - Math.PI/2) * 10 + centerPointX); 
      int yma=(int) (Math.sin(m_add_ten * Math.PI/30 - Math.PI/2) * 10 + centerPointY); 
      //************GET CURRENT MINUTE AND ALL INFORMATION TO DRAW MINUTE POINTER************** 

      //************GET CURRENT HOUR AND ALL INFORMATION TO DRAW HOUR POINTER************** 
      /**Information that i mean here is 
      *coordinate for hour pointer's corner. 
      *You can try change value 10 in xhm,yhm,xha and yha. 
      *After that, try compile and execute this program. 
      **/ 
      int h=currentDate.getHours(); 

      int h_minus_ten=h-10; 
      int h_add_ten=h+10; 

      int xh = (int) (Math.cos(h * Math.PI/6 - Math.PI/2) * 100 + centerPointX); 
      int yh = (int) (Math.sin(h * Math.PI/6 - Math.PI/2) * 100 + centerPointY); 

      int xhm=(int) (Math.cos(h_minus_ten * Math.PI/6 - Math.PI/2) * 10 + centerPointX); 
      int yhm=(int) (Math.sin(h_minus_ten * Math.PI/6 - Math.PI/2) * 10 + centerPointY); 

      int xha=(int) (Math.cos(h_add_ten * Math.PI/6 - Math.PI/2) * 10 + centerPointX); 
      int yha=(int) (Math.sin(h_add_ten * Math.PI/6 - Math.PI/2) * 10 + centerPointY);  
     } 
      if(England.isSelected()) 
     { 
        /**Information that i mean here is 
      *coordinate for second pointer's corner. 
      *You can try change value 5 in xsm,ysm,xsa and ysa. 
      *After that, try compile and execute this program. 
      **/ 
      int s=currentDate.getSeconds(); 

      int s_minus_five=s-5; 
      int s_add_five=s+5; 

      xs = (int) (Math.cos(s * Math.PI/30 - Math.PI/2) * 170 + centerPointX); 
      ys = (int) (Math.sin(s * Math.PI/30 - Math.PI/2) * 170 + centerPointY); 

      int xsm=(int) (Math.cos(s_minus_five * Math.PI/30 - Math.PI/2) * 5 + centerPointX); 
      int ysm=(int) (Math.sin(s_minus_five * Math.PI/30 - Math.PI/2) * 5 + centerPointY); 

      int xsa=(int) (Math.cos(s_add_five * Math.PI/30 - Math.PI/2) * 5 + centerPointX); 
      int ysa=(int) (Math.sin(s_add_five * Math.PI/30 - Math.PI/2) * 5 + centerPointY); 
      //************GET CURRENT SECOND AND ALL INFORMATION TO DRAW SECOND POINTER************** 

      //************GET CURRENT MINUTE AND ALL INFORMATION TO DRAW MINUTE POINTER************** 
      /**Information that i mean here is 
      *coordinate for minute pointer's corner. 
      *You can try change value 10 in xmm,ymm,xma and yma. 
      *After that, try compile and execute this program. 
      **/ 
      int m=currentDate.getMinutes(); 

      int m_minus_ten=m-10; 
      int m_add_ten=m+10; 

      int xm = (int) (Math.cos(m * Math.PI/30 - Math.PI/2) * 170 + centerPointX); 
      int ym = (int) (Math.sin(m * Math.PI/30 - Math.PI/2) * 170 + centerPointY); 

      int xmm=(int) (Math.cos(m_minus_ten * Math.PI/30 - Math.PI/2) * 10 + centerPointX); 
      int ymm=(int) (Math.sin(m_minus_ten * Math.PI/30 - Math.PI/2) * 10 + centerPointY); 

      int xma=(int) (Math.cos(m_add_ten * Math.PI/30 - Math.PI/2) * 10 + centerPointX); 
      int yma=(int) (Math.sin(m_add_ten * Math.PI/30 - Math.PI/2) * 10 + centerPointY); 
      //************GET CURRENT MINUTE AND ALL INFORMATION TO DRAW MINUTE POINTER************** 

      //************GET CURRENT HOUR AND ALL INFORMATION TO DRAW HOUR POINTER************** 
      /**Information that i mean here is 
      *coordinate for hour pointer's corner. 
      *You can try change value 10 in xhm,yhm,xha and yha. 
      *After that, try compile and execute this program. 
      **/ 
      int h=currentDate.getHours() - 2; 

      int h_minus_ten=h-10; 
      int h_add_ten=h+10; 

      int xh = (int) (Math.cos(h * Math.PI/6 - Math.PI/2) * 100 + centerPointX); 
      int yh = (int) (Math.sin(h * Math.PI/6 - Math.PI/2) * 100 + centerPointY); 

      int xhm=(int) (Math.cos(h_minus_ten * Math.PI/6 - Math.PI/2) * 10 + centerPointX); 
      int yhm=(int) (Math.sin(h_minus_ten * Math.PI/6 - Math.PI/2) * 10 + centerPointY); 

      int xha=(int) (Math.cos(h_add_ten * Math.PI/6 - Math.PI/2) * 10 + centerPointX); 
      int yha=(int) (Math.sin(h_add_ten * Math.PI/6 - Math.PI/2) * 10 + centerPointY);  
     } 
    } 
} 

public void paint(Graphics g) 
{ 
    centerPointX=getSize().width/2; 
    centerPointY=getSize().height/2; 

    currentDate=new Date(); 

    //************GET CURRENT SECOND AND ALL INFORMATION TO DRAW SECOND POINTER************** 

    //************GET CURRENT HOUR AND ALL INFORMATION TO DRAW HOUR POINTER************** 

    //OVAL THAT MAKE CLOCK CIRCLE 
    int ovalWidth=400; 
    int ovalHeight=400; 
    //OVAL THAT MAKE CLOCK CIRCLE 

    Graphics2D g2d=(Graphics2D)g; 

    super.paint(g2d); 

    //PEN COLOR TO DRAW : White 
    Color penColor=new Color(255,255,255); 

    //PEN COLOR TO DRAW : Black 
    Color penColor2=new Color(0,0,0); 

    //Clock circle background color 
    g2d.setColor(penColor); 
    g2d.fillOval(((getSize().width)/2)-(ovalWidth/2),((getSize().height)/2)-(ovalHeight/2),ovalWidth,ovalHeight); 

    //Draw "Quartz" text 
    g2d.setColor(penColor2); 
    quartzFont=new Font("Verdana",Font.BOLD,20); 
    g2d.setFont(quartzFont); 
    g2d.drawString("Quartz",centerPointX-30,centerPointY-100); 

    //Draw number 12,3,6 and 9 
    quartzFont=new Font("Verdana",Font.BOLD,50); 
    g2d.setFont(quartzFont); 
    g2d.drawString("12",centerPointX-30,centerPointY-120); 
    g2d.drawString("6",centerPointX-18,centerPointY+170); 
    g2d.drawString("3",centerPointX+140,centerPointY+13); 
    g2d.drawString("9",centerPointX-170,centerPointY+13); 

    //*************DRAW SECOND POINTER********* 
    int[]coordinateXs={centerPointX,xsm,xs,xsa}; 
    int[]coordinateYs={centerPointY,ysm,ys,ysa}; 
    g2d.fillPolygon(coordinateXs,coordinateYs,4); 
    //*************DRAW SECOND POINTER********* 

    //*************DRAW MINUTE POINTER********* 
    int[]coordinateXm={centerPointX,xmm,xm,xma}; 
    int[]coordinateYm={centerPointY,ymm,ym,yma}; 
    g2d.fillPolygon(coordinateXm,coordinateYm,4); 
    //*************DRAW MINUTE POINTER********* 

    //*************DRAW HOUR POINTER********* 
    int[]coordinateXh={centerPointX,xhm,xh,xha}; 
    int[]coordinateYh={centerPointY,yhm,yh,yha}; 
    g2d.fillPolygon(coordinateXh,coordinateYh,4); 
    //*************DRAW HOUR POINTER********* 

    //*************DRAW LINE TICK******************* 
    //Line tick that i mean here is, short line to indicate second. 
    //I hope you understand what i mean. 
    for(int i=1; i<=360; i++) 
    { 
     int tickX; 
     int tickY; 

     int tickXb; 
     int tickYb; 

     tickX=(int) (Math.cos(i * Math.PI/30 - Math.PI/2)* 180 + centerPointX); 
     tickY=(int) (Math.sin(i * Math.PI/30 - Math.PI/2)* 180 + centerPointY); 

     tickXb=(int) (Math.cos(i * Math.PI/30 - Math.PI/2) * 300 + centerPointX); 
     tickYb=(int) (Math.sin(i * Math.PI/30 - Math.PI/2) * 300 + centerPointY); 

     g2d.drawLine(tickXb,tickYb,tickX,tickY); 
    } 
    //*************DRAW LINE TICK******************* 
} 

public static void main(String[]args) 
{ 
    SimpleAnalogClock sac=new SimpleAnalogClock(); 
} 

}

Answer 1

http://itechnobuzzz.blogspot.in/2013/09/make-analog-clock-using-java.html 從上面的鏈接u必須在Java中模擬時鐘的答案..

Answer 2

HI這是我用一個模擬時鐘代碼下拉菜單選擇國家。

這是一個java代碼。 如果在運行代碼或編譯代碼時出現任何問題，請與我聯繫。

package clock; 
import java.awt.event.*; 
import javax.swing.*; 
import java.text.*; 
import java.util.*; 
import java.awt.*; 

public class Clock extends JPanel implements Runnable,ActionListener { 
    public static JMenu jMenu1=new JMenu(); 
    public static JMenu jMenu2=new JMenu(); 
    public static JMenu jMenu3=new JMenu(); 
    public static JMenuBar jMenuBar1=new JMenuBar(); 
    public static JMenuItem jMenuItem1=new JMenuItem(); 
    public static JMenuItem jMenuItem2=new JMenuItem(); 
    public static JMenuItem jMenuItem3=new JMenuItem(); 
    public static JMenuItem jMenuItem4=new JMenuItem(); 
    public static JMenuItem jMenuItem5=new JMenuItem(); 
    public static JMenuItem jMenuItem6=new JMenuItem(); 
    public static JMenuItem jMenuItem7=new JMenuItem(); 
    public static JMenuItem jMenuItem8=new JMenuItem(); 
    public static JMenuItem jMenuItem9=new JMenuItem(); 
    public static String [] array = {"Europe/Copenhagen","US/Michigan","Asia/Istanbul","Iran","Asia/Singapore","Australia/LHI"}; 
    public static JComboBox dropdown = new JComboBox(array); 
    public static JLabel label = new JLabel("Label"); 

    public static int seconds,minutes,hours; 
    public static String timezone = "Europe/Copenhagen"; 
    Thread thread = null; 
    SimpleDateFormat formatter = new SimpleDateFormat("s", Locale.getDefault()); 
    Date currentDate; 
    int xcenter = 175, ycenter = 175, lastxs = 0, lastys = 0, lastxm = 0, lastym = 0, lastxh = 0,lastyh = 0; 

    private void drawStructure(Graphics g) 
    { 
     Color customColor = new Color(240,240,240); 
     g.setColor(customColor); 
     g.drawRect(10, 0, 600, 600); 
     g.fillRect(0, 0, 600, 600); 
     g.setFont(new Font("TimesRoman", Font.BOLD, 20)); 
     g.setColor(Color.WHITE); 
     g.fillOval(xcenter - 170, ycenter - 170, 300, 300); 
     g.setColor(Color.BLACK); 
     g.drawString("12", xcenter - 30, ycenter - 150); 
     g.drawString(".",xcenter + 50,ycenter - 140); 
     g.drawString(".",xcenter + 100, ycenter - 90); 
     g.drawString("3", xcenter + 115, ycenter - 20); 
     g.drawString(".",xcenter + 100, ycenter + 50); 
     g.drawString(".", xcenter + 50, ycenter + 100); 
     g.drawString("6", xcenter - 30, ycenter + 125); 
     g.drawString(".",xcenter - 90, ycenter + 100); 
     g.drawString(".",xcenter - 140,ycenter +50); 
     g.drawString("9", xcenter - 165, ycenter -20); 
     g.drawString(".", xcenter - 140, ycenter -90); 
     g.drawString(".",xcenter - 90,ycenter -140); 
    } 

    public void paint(Graphics g) 
    { 
     int xhour, yhour, xminute, yminute, xsecond, ysecond, second, minute, hour; 
     drawStructure(g); 
     currentDate = offsetTimeZone(new Date(), "Asia/Kolkata", timezone); 
     //System.out.println("date:"+currentDate); 
     formatter.applyPattern("s"); 
     second = Integer.parseInt(formatter.format(currentDate)); 
     formatter.applyPattern("m"); 
     minute = Integer.parseInt(formatter.format(currentDate)); 
     formatter.applyPattern("h"); 
     hour = Integer.parseInt(formatter.format(currentDate)); 
     //System.out.println("second="+second+",minute="+minute+",hour="+hour); 
     seconds = second; 
     minutes = minute; 
     hours = hour; 
     this.label.setBackground(Color.red); 
     label.setText(hours+" : "+minutes+" : "+seconds); 
     this.label.setBackground(Color.red); 
     xsecond = (int) (Math.cos(second * 3.14f/30 - 3.14f/2) * 120 + xcenter-20); 
     ysecond = (int) (Math.sin(second * 3.14f/30 - 3.14f/2) * 120 + ycenter-20); 
     xminute = (int) (Math.cos(minute * 3.14f/30 - 3.14f/2) * 100 + xcenter-20); 
     yminute = (int) (Math.sin(minute * 3.14f/30 - 3.14f/2) * 100 + ycenter-20); 
     xhour = (int) (Math.cos((hour * 30 + minute/2) * 3.14f/180 - 3.14f/2) * 80 + xcenter-20); 
     yhour = (int) (Math.sin((hour * 30 + minute/2) * 3.14f/180 - 3.14f/2) * 80 + ycenter-20); 
     // Erase if necessary, and redraw 
     g.setColor(Color.magenta); 
     if (xsecond != lastxs || ysecond != lastys) 
      g.drawLine(xcenter-20, ycenter-20, lastxs, lastys); 
     if (xminute != lastxm || yminute != lastym) 
     { 
      g.drawLine(xcenter-20, ycenter - 21, lastxm, lastym); 
      g.drawLine(xcenter - 21, ycenter-20, lastxm, lastym); 
     } 
     if (xhour != lastxh || yhour != lastyh) 
     { 
      g.drawLine(xcenter-20, ycenter - 21, lastxh, lastyh); 
      g.drawLine(xcenter - 21, ycenter-20, lastxh, lastyh); 
     } 
     g.setColor(Color.black); 
     g.drawLine(xcenter-20, ycenter-20, xsecond, ysecond); 
     g.setColor(Color.BLACK); 
     g.drawLine(xcenter-20, ycenter - 21, xminute, yminute); 
     g.drawLine(xcenter - 21, ycenter-20, xminute, yminute); 
     g.setColor(Color.BLACK); 
     g.drawLine(xcenter-20, ycenter - 21, xhour, yhour); 
     g.drawLine(xcenter - 21, ycenter-20, xhour, yhour); 
     lastxs = xsecond; 
     lastys = ysecond; 
     lastxm = xminute; 
     lastym = yminute; 
     lastxh = xhour; 
     lastyh = yhour; 
    } 

    public void start() 
    { 
     if (thread == null) 
     { 
      thread = new Thread(this); 
      thread.start(); 
     } 
    } 

    public void stop() 
    { 
     thread = null; 
    } 

    public void run() 
    { 
     while (thread != null) 
     { 
      try 
      { 
       Thread.sleep(100); 
      } 
      catch (InterruptedException e){} 
      repaint(); 
     } 
     thread = null; 
    } 

    public void update(Graphics g) 
    { 
     paint(g); 
    } 

    private static Date offsetTimeZone(Date date, String fromTZ, String toTZ) 
    { 
     // Construct FROM and TO TimeZone instances 
     TimeZone fromTimeZone = TimeZone.getTimeZone(fromTZ); 
     TimeZone toTimeZone = TimeZone.getTimeZone(toTZ); 

     // Get a Calendar instance using the default time zone and locale. 
     Calendar calendar = Calendar.getInstance(); 

     // Set the calendar's time with the given date 
     calendar.setTimeZone(fromTimeZone); 
     calendar.setTime(date); 

     //System.out.println("Input: " + calendar.getTime() + " in " + fromTimeZone.getDisplayName()); 

     // FROM TimeZone to UTC 
     calendar.add(Calendar.MILLISECOND, fromTimeZone.getRawOffset() * -1); 

     if (fromTimeZone.inDaylightTime(calendar.getTime())) 
      calendar.add(Calendar.MILLISECOND, calendar.getTimeZone().getDSTSavings() * -1); 

     // UTC to TO TimeZone 
     calendar.add(Calendar.MILLISECOND, toTimeZone.getRawOffset()); 

     if (toTimeZone.inDaylightTime(calendar.getTime())) 
      calendar.add(Calendar.MILLISECOND, toTimeZone.getDSTSavings()); 

     return calendar.getTime(); 
    } 

    public static void main(String[] args) { 
     // TODO code application logic here 
     JFrame window = new JFrame(); 
     window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
     window.setSize(350, 500); 
     window.setLayout(new GridBagLayout()); 
     Clock clock = new Clock(); 
     GridBagConstraints c = new GridBagConstraints(); 
     c.fill = GridBagConstraints.HORIZONTAL; 
    c.ipady = 20;  //make this component tall 
    //c.weightx = 0.0; 
    //c.gridwidth = 100; 
     c.ipadx=190; 
    c.gridx = 0; 
    c.gridy = 0; 
    window.setJMenuBar(jMenuBar1); 
     window.add(dropdown,c); 
     //window.add(Constants.p1); 
     //label.setSize(500, 100); 
//  label.setBackground(Color.black); 
//  Constants.p1.add(dropdown); 
//  Constants.p1.add(label); 
     c.fill = GridBagConstraints.HORIZONTAL; 
    c.ipady = 20;  //make this component tall 
    //c.weightx = 0.0; 
    //c.gridwidth = 100; 
    c.gridx = 0; 
    c.gridy = 1; 
     window.add(label,c); 
     c.fill = GridBagConstraints.HORIZONTAL; 
    c.ipady = 300;  //make this component tall 
     c.ipadx=300; 
    //c.weightx = 0.0; 
    c.gridwidth = 1000; 
    c.gridx = 0; 
    c.gridy = 2; 
     //window.add(dropdown,c); 
     window.add(clock,c); 
     //window.add(p2); 
     window.setVisible(true); 
     clock.start(); 
    } 

    public Clock() 
    { 
     //Constants.p1.setSize(new Dimension(500, 500)); 
     jMenu1.setText("View"); 
     jMenu1.setToolTipText(""); 
     jMenu1.setFont(new java.awt.Font("Segoe UI", 1, 12)); // NOI18N 
     jMenuItem1.setAccelerator(javax.swing.KeyStroke.getKeyStroke(java.awt.event.KeyEvent.VK_1, java.awt.event.InputEvent.ALT_MASK)); 
     jMenuItem1.setText("Tax Caculator"); 
     jMenu1.add(jMenuItem1); 

     jMenuItem2.setAccelerator(javax.swing.KeyStroke.getKeyStroke(java.awt.event.KeyEvent.VK_2, java.awt.event.InputEvent.ALT_MASK)); 
     jMenuItem2.setText("Length Calculator"); 
     jMenu1.add(jMenuItem2); 
     jMenuItem3.setAccelerator(javax.swing.KeyStroke.getKeyStroke(java.awt.event.KeyEvent.VK_3, java.awt.event.InputEvent.ALT_MASK)); 
     jMenuItem3.setText("Currency Calculator"); 
     jMenu1.add(jMenuItem3); 
     jMenuItem4.setAccelerator(javax.swing.KeyStroke.getKeyStroke(java.awt.event.KeyEvent.VK_4, java.awt.event.InputEvent.ALT_MASK)); 
     jMenuItem4.setText("Time Calculator"); 
     jMenu1.add(jMenuItem4); 

     jMenuBar1.add(jMenu1); 

     jMenu2.setText("Edit"); 
     jMenuItem5.setAccelerator(javax.swing.KeyStroke.getKeyStroke(java.awt.event.KeyEvent.VK_X, java.awt.event.InputEvent.CTRL_MASK)); 
     jMenuItem5.setText("Cut"); 
     jMenu2.add(jMenuItem5); 
     jMenuItem6.setAccelerator(javax.swing.KeyStroke.getKeyStroke(java.awt.event.KeyEvent.VK_C, java.awt.event.InputEvent.CTRL_MASK)); 
     jMenuItem6.setText("Copy"); 
     jMenu2.add(jMenuItem6); 
     jMenuItem7.setAccelerator(javax.swing.KeyStroke.getKeyStroke(java.awt.event.KeyEvent.VK_V, java.awt.event.InputEvent.CTRL_MASK)); 
     jMenuItem7.setText("Paste"); 
     jMenu2.add(jMenuItem7); 
     jMenuBar1.add(jMenu2); 

     jMenu3.setText("Help"); 
     jMenuItem8.setAccelerator(javax.swing.KeyStroke.getKeyStroke(java.awt.event.KeyEvent.VK_F1, 0)); 
     jMenuItem8.setText("Help"); 
     jMenu3.add(jMenuItem8); 
     jMenuItem9.setText("About Calculator"); 
     jMenu3.add(jMenuItem9); 
     jMenuBar1.add(jMenu3); 

     dropdown.addActionListener(this); 
    } 

    @Override 
    public void actionPerformed(ActionEvent e) 
    { 
     Object instance = dropdown.getSelectedItem(); 
     timezone = instance.toString(); 
     //System.out.println(timezone); 
     repaint(); 
    } 
}