Java Data Type How to - Do date math in Timezone

Question

We would like to know how to do date math in Timezone.
Answer

import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.TimeZone;
// w  ww.  j  a v  a  2s .  co  m
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JSpinner;
import javax.swing.SpinnerDateModel;
import javax.swing.SwingUtilities;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;

public class Main {

  public static void main(String[] args) {
    SwingUtilities.invokeLater(new Runnable() {

      @Override
      public void run() {
        new TimeZoneSpinners().makeUI();
      }
    });
  }
}
class TimeZoneSpinners {
  public void makeUI() {
    String[] zones = { "Asia/Tokyo", "Asia/Hong_Kong",
        "Asia/Calcutta", "Europe/Paris", "Europe/London", "America/New_York",
        "America/Los_Angeles" };
    JLabel[] labels = new JLabel[zones.length];
    SimpleDateFormat[] formats = new SimpleDateFormat[zones.length];
    JFrame frame = new JFrame();

    Calendar cal = Calendar.getInstance();
    Date date = cal.getTime();
    SpinnerDateModel model = new SpinnerDateModel();
    model.setValue(date);
    JSpinner spinner = new JSpinner(model);
    spinner.addChangeListener(new ChangeListener() {

      @Override
      public void stateChanged(ChangeEvent e) {
        Date date = (Date) ((JSpinner) e.getSource()).getValue();
        for (int i = 0; i < labels.length; i++) {
          labels[i].setText(formats[i].format(date));
        }
      }
    });
    SimpleDateFormat format = ((JSpinner.DateEditor) spinner.getEditor()).getFormat();
    format.setTimeZone(TimeZone.getTimeZone(zones[0]));
    format.applyPattern("yyyy-MM-dd HH:mm:ss");
    JPanel panel = new JPanel(new GridLayout(zones.length, 2, 10, 10));
    for (int i = 0; i < zones.length; i++) {
      formats[i] = new SimpleDateFormat("yyyy-MMM-dd HH:mm:ss");
      formats[i].setTimeZone(TimeZone.getTimeZone(zones[i]));
      JLabel label = new JLabel(zones[i]);
      labels[i] = new JLabel(formats[i].format(date));
      panel.add(label);
      panel.add(labels[i]);
    }
    frame.setLayout(new BorderLayout());
    frame.add(spinner, BorderLayout.NORTH);
    frame.add(panel, BorderLayout.CENTER);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.pack();
    frame.setVisible(true);
  }
}