gistfile1.java

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.Font;
import java.time.Duration;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.time.temporal.ChronoUnit;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;

import javax.swing.JFrame;
import javax.swing.JLabel;

public class Countdown {
  private static final Duration TIMEPOINT = Duration.ofSeconds(7037);
  private static final LocalDateTime MIDNIGHT = LocalDate.now().atTime(LocalTime.of(23, 59, 59)).plus(2, ChronoUnit.SECONDS);

  private JLabel timeLabel = new JLabel("");
  private ScheduledExecutorService executor = Executors.newSingleThreadScheduledExecutor();

  /**
   * Create the GUI and show it. For thread safety, this method should be
   * invoked from the event-dispatching thread.
   */
  private Countdown() {
    // Create and set up the window.
    JFrame frame = new JFrame("FrameDemo");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.getContentPane().add(timeLabel, BorderLayout.CENTER);
    timeLabel.setPreferredSize(new Dimension(175, 100));
    
    Font labelFont = timeLabel.getFont();
    // Set the label's font size to the newly determined size.
    timeLabel.setFont(new Font(labelFont.getName(), Font.PLAIN, 48));
    // Display the window.
    frame.pack();
    frame.setVisible(true);
    executor.scheduleAtFixedRate(()->{
      javax.swing.SwingUtilities.invokeLater(()->{
        LocalDateTime now = LocalDateTime.now();
        long until = now.until(MIDNIGHT, ChronoUnit.SECONDS);
        Duration x = TIMEPOINT.minus(until, ChronoUnit.SECONDS);
        timeLabel.setText(formatTime(until) + "   \n" + formatTime(x.get(ChronoUnit.SECONDS)));
      });
    }, 100, 100, TimeUnit.MILLISECONDS);
  }

  public static String formatTime(long time) {
    long hours = 0, minutes = 0, seconds = 0;
    while (time >= 3600) {
      time -= 3600;
      ++hours;
    }
    while (time >= 60) {
      time -= 60;
      ++minutes;
    }
    seconds = time;
    return String.format("%02d:%02d:%02d", hours, minutes, seconds);
  }
  
  public static void main(String[] args) {
    // Schedule a job for the event-dispatching thread:
    // creating and showing this application's GUI.
    javax.swing.SwingUtilities.invokeLater(new Runnable() {
      @Override
      public void run() {
        new Countdown();
      }
    });
  }
}