Question

I am on a project to capture the interval time in hh:mm.
I have 2 buttons named btnTimeOut & btnTimeIn both capturing the system time when clicked.
The requirement is to get the interval between the btnTimeOut & btnTime in hh:mm, etc. 12:30 – 10:00 = 02:30 (hh:mm).

Currently I used the following codes for the interval but it returns as minutes, etc. 12:30 – 10:00 = 150 minutes.

  String timeOut = lblTimeOut.getText();
  String timeIn = lblTimeIn2.getText();

  SimpleDateFormat format = new SimpleDateFormat("hh:mm");

  Date d1 = null;
  Date d2 = null;

  try {
      d1 = format.parse(timeOut);
      d2 = format.parse(timeIn);
  } 
  catch (Exception e){
      e.printStackTrace();
  }

  long diff = d2.getTime() - d1.getTime();
  long diffMinutes = diff / (60 * 1000);         
  long diffHours = diff / (60 * 60 * 1000);  

  lblSurface.setText(String.valueOf(diffMinutes)); 

How to get the duration in the form hh:mm?

I used Joda time and return with Invalid format: “12:19” is malformed at “:19”.
As for my other buttons which trigger the display time.

DateFormat timeFormat = new SimpleDateFormat("hh:mm");
Date date = new Date();  
String time = timeFormat.format(date);  
lblTimeIn2.setText(time);

Timer timer = new Timer(1000, timerListener);  
    // to make sure it doesn't wait one second at the start  
timer.setInitialDelay(0);  
timer.start();   
}         

I’ve no idea what is wrong, do I need to use joda time for displaying time for my other label too?

Answer 1

I, personally, would use JodaTime as it takes into account things like difference between days (ie the difference between 23:30-02:30) and has nice inbuilt formatters

public class TestJodaTime {

    public static void main(String[] args) {

        DateTime start = new DateTime(2012, 11, 11, 23, 30, 0, 0);
        DateTime end = new DateTime(2012, 11, 12, 1, 30, 0, 0);
        Interval interval = new Interval(start, end);
        Period toPeriod = interval.toPeriod();

        PeriodFormatter dateFormat = new PeriodFormatterBuilder()
                        .printZeroAlways().minimumPrintedDigits(2)
            .appendHours().minimumPrintedDigits(2)
            .appendSeparator(":")
            .appendMinutes().minimumPrintedDigits(2)
            .toFormatter();        
        System.out.println(toPeriod.toString(dateFormat));
    }
}

Which will output 02:00

Extended example

public class TestJodaTime {

    public static void main(String[] args) {
        new TestJodaTime();
    }

    public TestJodaTime() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException ex) {
                } catch (InstantiationException ex) {
                } catch (IllegalAccessException ex) {
                } catch (UnsupportedLookAndFeelException ex) {
                }

                JFrame frame = new JFrame("Test");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setLayout(new BorderLayout());
                frame.add(new JodaPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }

        });
    }

    public class JodaPane extends JPanel {

        private JTextField startHour;
        private JTextField startMin;
        private JTextField endHour;
        private JTextField endMin;
        private JButton diffButton;
        private JLabel lblDiff;
        private JButton markStart;
        private JButton markEnd;
        private Timer timer;
        private JLabel realTime;

        public JodaPane() {

            markStart = new JButton("Mark");
            markEnd = new JButton("Mark");

            startHour = new JTextField(2);
            startMin = new JTextField(2);
            endHour = new JTextField(2);
            endMin = new JTextField(2);
            diffButton = new JButton("=");
            lblDiff = new JLabel("00:00");
            realTime = new JLabel("00:00.00");

            setLayout(new GridBagLayout());
            GridBagConstraints gbc = new GridBagConstraints();
            gbc.gridx = 0;
            gbc.gridy = 0;
            gbc.anchor = GridBagConstraints.WEST;
            add(new JLabel("From"), gbc);
            gbc.gridx++;
            add(startHour, gbc);
            gbc.gridx++;
            add(new JLabel(":"), gbc);
            gbc.gridx++;
            add(startMin, gbc);
            gbc.gridx++;
            add(markStart, gbc);
            gbc.gridx++;
            add(new JLabel(" to "), gbc);
            gbc.gridx++;
            add(endHour, gbc);
            gbc.gridx++;
            add(new JLabel(":"), gbc);
            gbc.gridx++;
            add(endMin, gbc);
            gbc.gridx++;
            add(markEnd, gbc);
            gbc.gridx++;
            add(diffButton, gbc);
            gbc.gridx++;
            add(lblDiff, gbc);

            gbc.gridy++;
            add(realTime, gbc);

            diffButton.addActionListener(new ActionListener() {
                public boolean isValid(JTextField field) {
                    return field.getText() != null && field.getText().length() > 0;
                }
                @Override
                public void actionPerformed(ActionEvent ae) {
                    if (isValid(startHour) && isValid(startMin)
                                    && isValid(endHour) && isValid(endMin)) {
                        int hourStart = Integer.parseInt(startHour.getText());
                        int minStart = Integer.parseInt(startMin.getText());
                        int hourEnd = Integer.parseInt(endHour.getText());
                        int minEnd = Integer.parseInt(endMin.getText());

                        String prefix = "";
                        if (hourEnd < hourStart) {
                            int tmp = hourStart;
                            hourStart = hourEnd;
                            hourEnd = tmp;
                            prefix = "-";
                        }

                        System.out.println("Start = " + hourStart + ":" + minStart);
                        System.out.println("End = " + hourEnd + ":" + minEnd);

                        DateTime start = new DateTime(0, 1, 1, hourStart, minStart, 0, 0);
                        DateTime end = new DateTime(0, 1, 1, hourEnd, minEnd, 0, 0);
                        Interval interval = new Interval(start, end);
                        Period toPeriod = interval.toPeriod();

                        PeriodFormatter dateFormat = new PeriodFormatterBuilder()
                                        .printZeroAlways().minimumPrintedDigits(2)
                                        .appendHours().minimumPrintedDigits(2)
                                        .appendSeparator(":")
                                        .appendMinutes().minimumPrintedDigits(2)
                                        .toFormatter();
                        lblDiff.setText(prefix + dateFormat.print(toPeriod));
                    }
                }

            });

            markStart.addActionListener(new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent ae) {
                    Calendar cal = Calendar.getInstance();
                    startHour.setText(Integer.toString(cal.get(Calendar.HOUR_OF_DAY)));
                    startMin.setText(Integer.toString(cal.get(Calendar.MINUTE)));
                    diffButton.doClick();
                }

            });
            markEnd.addActionListener(new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent ae) {
                    Calendar cal = Calendar.getInstance();
                    endHour.setText(Integer.toString(cal.get(Calendar.HOUR_OF_DAY)));
                    endMin.setText(Integer.toString(cal.get(Calendar.MINUTE)));
                    diffButton.doClick();
                }

            });

            timer = new Timer(500, new ActionListener() {
                private SimpleDateFormat sdf = new SimpleDateFormat("HH:mm.ss");
                @Override
                public void actionPerformed(ActionEvent ae) {
                    realTime.setText(sdf.format(new Date()));
                }
            });
            timer.setRepeats(true);
            timer.setCoalesce(true);
            timer.start();


        }

    }

}

Your questions a little vague, so I’ve done a wide example. Mark, basically auto fills the fields with the current time.

There is little validation 😉