getting the time in milliseconds

[sean beacham]

why is it when i set this:

	Calendar now = Calendar.getInstance();
			System.out.println(now.getTimeInMillis());

The date starts from 1970???

my last reading in milli seconds was this 1302647947945 which turns out to be 41 years!!

i just want the specific time of the day in milliseconds

[Bear Bibeault]

Time is stored as number of milliseconds since Jan 1, 1970. If you want the milliseconds within the current day, you'll need to do some math.

[sean beacham]

what kind of equation surely there must be a statement for get current time in milliseconds for the day? :\
i know :\
1 hour = 3600000

[Paul Clapham]

sean beacham wrote:surely there must be a statement for get current time in milliseconds for the day? :\

Well, actually, no, there isn't. You say that as if it's a common thing to need the number of milliseconds since midnight, but I don't think it is.

So before we get into the calculations for finding that number (which are more complicated than you might think), can you tell us why you think you need that number?

[Campbell Ritchie]

If you need the milliseconds since midnight, you can get the hour, minute and second and multiply them.
Note the millisecond method is not precise; some computers used to work to the nearest 0.1s, so milliseconds were only precise to the nearest 100.

[Jesper de Jong]

Another way:

Get a Calendar object, set it to today, and set the hours, minutes, seconds and milliseconds to 0. Call getTimeInMillis() on it.

Call System.currentTimeMillis() to get the current time in milliseconds. Subtract the value that you got above from it, and you have the number of milliseconds since midnight.

[sean beacham]

Jesper de Jong wrote:Another way:

Get a Calendar object, set it to today, and set the hours, minutes, seconds and milliseconds to 0. Call getTimeInMillis() on it.

Call System.currentTimeMillis() to get the current time in milliseconds. Subtract the value that you got above from it, and you have the number of milliseconds since midnight.

will that refresh for every day?

what im trying to do is this.... https://coderanch.com/t/534155/GUI/java/Swing-Calender-ComboBox-timer-questions

i have explained it there im at witts end with it right now :\

[Jesper de Jong]

sean beacham wrote:will that refresh for every day?

I'm not sure what you mean by that. When you call System.currentTimeMillis(), you get the time at the moment you're calling it.

[sean beacham]

ok what i mean is

the user has set the timer for continous use until the timer is reprogrammed therefore i want it to check the time constantly and when the time corresponding time arrives Turn On & Off the boiler sets the variable to switch off? do you understand what i mean? So obviously it needs to know when to turn on and off so its comparing the time the user has set to the time on the pc.

[Jesper de Jong]

Have a look at class java.util.Timer, which will let you schedule a task to be executed at a particular date and time.

[sean beacham]

i changed my mind about getting time in milliseconds im now using gregorian calender which gets the current hour and minute

but right now im getting a silly error, all elements in this statement are ints now i dont get why its being a pain!

The operator && is undefined for the argument type(s) int, boolean

for this specific line:

if (hourOn && minOn == timerhour24 && timermin)

the full code is here:

	public void boilertimer() {
		frame4 = new JFrame();
		frame4.setTitle("my Thermostat Boiler Timer");
		frame4.setSize(300, 200);

		//sets up panel
		panel4 = new JPanel();
		panel4.setBackground(Color.WHITE);
		panel4.setLayout(null);
		frame4.getContentPane().add(panel4);
		frame4.setVisible(true);
		panel4.setVisible(true);

		Calendar cal = new GregorianCalendar();

		//Get the components of the time
		final int timerhour24 = cal.get(Calendar.HOUR_OF_DAY);     // 0..23
		final int timermin = cal.get(Calendar.MINUTE);             // 0..59

		System.out.println(timerhour24 + ":" + timermin);

		String[] hourStrings = { "00", "01", "02", "03", "04", "05", "06", "07", "08",
                                                            "09", "10", "11", "12", "13", "14", "15", "16" , "17",
                                                            "18", "19", "20", "21", "22", "23"};
		String[] minuteStrings = { "00", "01", "02", "03", "04", "05", "06", "07", "08",
                                                                "09", "10", "11", "12", "13", "14", "15", "16" , "17",
                                                                "18", "19", "20", "21", "22", "23","24", "25", "26" ,
                                                                "27", "28", "29", "30", "40", "41", "42", "43", "44", 
                                                                "45", "46" , "47", "48", "49", "50", "51", "52", "53",
                                                               "54", "55", "56" , "57", "58", "59"};

		String[] hourStringsoff = { "00", "01", "02", "03", "04", "05", "06", "07", "08", "09", "10", "11",
                                                                "12", "13", "14", "15", "16" , "17", "18", "19", "20", "21", "22", "23"};
		String[] minuteStringsoff = { "00", "01", "02", "03", "04", "05", "06", "07", "08", "09", "10", "11",
                                                                     "12", "13", "14", "15", "16" , "17", "18", "19", "20", "21", "22", "23",
                                                                    "24", "25", "26" , "27", "28", "29", "30", "40", "41", "42", "43", "44", 
                                                                    "45", "46" , "47", "48", "49", "50", "51", "52", "53","54", "55", "56" , 
                                                                    "57", "58", "59"};

		BoilerOn = new JLabel("Boiler Switch On");
		BoilerOn.setBounds(10,10,100,50);
		panel4.add(BoilerOn);

		BoilerOff = new JLabel("Boiler Switch Off");
		BoilerOff.setBounds(140,10,125,50);
		panel4.add(BoilerOff);

		final JComboBox hour = new JComboBox(hourStrings);
		hour.setBounds(10,50,45,25);
		panel4.add(hour);
		hour.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				String hor = (String)hour.getSelectedItem();
				int hourOn = Integer.parseInt(hor);
				System.out.print(hourOn);
			}
		});

		final JComboBox minute = new JComboBox(minuteStrings);
		minute.setBounds(60,50,45,25);
		panel4.add(minute);
		minute.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				String min = (String)minute.getSelectedItem();
				int minOn = Integer.parseInt(min);
				System.out.print(minOn);
			}
		});

		final JComboBox houroff = new JComboBox(hourStringsoff);
		houroff.setBounds(140,50,45,25);
		panel4.add(houroff);
		houroff.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				String hor = (String)houroff.getSelectedItem();
				int hourOff = Integer.parseInt(hor);
				System.out.print(hourOff);
			}
		});

		final JComboBox minuteoff = new JComboBox(minuteStringsoff);
		minuteoff.setBounds(190,50,45,25);
		panel4.add(minuteoff);
		minuteoff.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				String min = (String)minuteoff.getSelectedItem();
				int minOff = Integer.parseInt(min);
				System.out.print(minOff);
			}
		});

		timerset = new JButton("Confirm");
		timerset.setBounds(155,115,80,40);
		panel4.add(timerset);
		timerset.addActionListener(new ActionListener()
		{public void actionPerformed(ActionEvent event) 
		{
			if (hourOn && minOn == timerhour24 && timermin){

				System.out.print("Boiler is On");
			}

		}});


	}

[Campbell Ritchie]

You can't use the && operator like that. I am not quite sure what that means, but do you mean you want a particular turn-on time? You would probably want if (min == minOn && hour == HourOn) . . .
By the way: there is a better way to fill your arrays, which I edited to shorten the lines.

public static final int MINUTES_IN_HOUR = 60;
 . . .
String[] minutesStrings = new String[MINUTES_IN_HOUR];
for (int i = 0; i < minuteStrings.length; i++)
{
   minutesStrings[i] = String.format("%02d", i);
}

I am not sure why you need those String arrays at all. You can print out the numbers with the %d tag and not use Strings.

[sean beacham]

Campbell Ritchie wrote:You can't use the && operator like that. I am not quite sure what that means, but do you mean you want a particular turn-on time? You would probably want if (min == minOn && hour == HourOn) . . .
By the way: there is a better way to fill your arrays, which I edited to shorten the lines.

public static final int MINUTES_IN_HOUR = 60;
 . . .
String[] minutesStrings = new String[MINUTES_IN_HOUR];
for (int i = 0; i < minuteStrings.length; i++)
{
   minutesStrings[i] = String.format("%02d", i);
}

I am not sure why you need those String arrays at all. You can print out the numbers with the %d tag and not use Strings.

yes i want to switch something on at a particular time ive modified my code and thats working thankyou although values of 00-09 only produce 1 digit so 00=0 and 09=9 its strange!

1 other thing my statement does nothing!

	public void boilertimer() {
		frame4 = new JFrame();
		frame4.setTitle("my Thermostat Boiler Timer");
		frame4.setSize(300, 200);

		//sets up panel
		panel4 = new JPanel();
		panel4.setBackground(Color.WHITE);
		panel4.setLayout(null);
		frame4.getContentPane().add(panel4);
		frame4.setVisible(true);
		panel4.setVisible(true);

		Calendar cal = new GregorianCalendar();

		//Get the components of the time
		final int timerhour24 = cal.get(Calendar.HOUR_OF_DAY);     // 0..23
		final int timermin = cal.get(Calendar.MINUTE);             // 0..59

		System.out.println(timerhour24 + ":" + timermin);

		final int MINUTES_IN_HOUR = 60;
		final int NO_OF_HOUR = 24;
		
		String[] minutesStrings = new String[MINUTES_IN_HOUR];
		for (int i = 0; i < minutesStrings.length; i++)
		{
		   minutesStrings[i] = String.format("%02d", i);
		}
		
		String[] hourStrings = new String[NO_OF_HOUR];
		for (int i = 0; i < hourStrings.length; i++)
		{
			hourStrings[i] = String.format("%02d", i);
		}
		
		String[] minutesStringsoff = new String[MINUTES_IN_HOUR];
		for (int i = 0; i < minutesStringsoff.length; i++)
		{
		   minutesStringsoff[i] = String.format("%02d", i);
		}
		
		String[] hourStringsoff = new String[NO_OF_HOUR];
		for (int i = 0; i < hourStringsoff.length; i++)
		{
			hourStringsoff[i] = String.format("%02d", i);
		}
		
		BoilerOn = new JLabel("Boiler Switch On");
		BoilerOn.setBounds(10,10,100,50);
		panel4.add(BoilerOn);

		BoilerOff = new JLabel("Boiler Switch Off");
		BoilerOff.setBounds(140,10,125,50);
		panel4.add(BoilerOff);

		final JComboBox hour = new JComboBox(hourStrings);
		hour.setBounds(10,50,45,25);
		panel4.add(hour);
		hour.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				String hor = (String)hour.getSelectedItem();
				int hourOn = Integer.parseInt(hor);
				System.out.print(hourOn);
			}
		});

		final JComboBox minute = new JComboBox(minutesStrings);
		minute.setBounds(60,50,45,25);
		panel4.add(minute);
		minute.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				String min = (String)minute.getSelectedItem();
				int minOn = Integer.parseInt(min);
				System.out.print(minOn);
			}
		});

		final JComboBox houroff = new JComboBox(hourStringsoff);
		houroff.setBounds(140,50,45,25);
		panel4.add(houroff);
		houroff.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				String hor = (String)houroff.getSelectedItem();
				int hourOff = Integer.parseInt(hor);
				System.out.print(hourOff);
			}
		});

		final JComboBox minuteoff = new JComboBox(minutesStringsoff);
		minuteoff.setBounds(190,50,45,25);
		panel4.add(minuteoff);
		minuteoff.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				String min = (String)minuteoff.getSelectedItem();
				int minOff = Integer.parseInt(min);
				System.out.print(minOff);
			}
		});
		System.out.println(hourOn);
		System.out.println(" ");
		System.out.println(timerhour24);
		
		timerset = new JButton("Confirm");
		timerset.setBounds(155,115,80,40);
		panel4.add(timerset);
		timerset.addActionListener(new ActionListener()
		{public void actionPerformed(ActionEvent event) 
		{
			if (timerhour24 == hourOn && timermin == minOn){
				System.out.println("Turn Boiler On");
			}
			else{
				System.out.println("Turn Boiler Off");
			}
		}});


	}

[sean beacham]

i manged to fix the statement problem i was showing my instance variables so i had to remove the int on this statement

int hourOn = Integer.parseInt(hor);

still havent fixed the 00 to 09 problem though :\

[Campbell Ritchie]

sean beacham wrote:. . . thats working thankyou although values of 00-09 only produce 1 digit so 00=0 and 09=9 its strange! . . .

You're welcome

I am surprised you are getting 0 rather than 00. Try this, and I bet you will get 00.

public class PercentDemo
{
    public static final int MINUTES_IN_HOUR = 60;
    
    public static void main(String[] args)
    {
        for (int i = 0; i < MINUTES_IN_HOUR; i++)
        {
            System.out.println(String.format("%02d", i));
        }
    }
}

Which statement does nothing?
Why are you using null layour and setBounds?

[sean beacham]

the statement works perfectly fine now thankyou i fixed that yesterday.

im now using swing timers to loop the statement to see if it will change however the gregorian calender only seems to run once that is when you first open the program. Ive tried putting a timer around it and an infinate for loop to see if that works but it doesnt its quite annoying! i kept getting an error. Therefore timerhour24 timermin is a static time that at the time you open the program! and i want to update it in real time.

	public void boilertimer() {
		frame4 = new JFrame();
		frame4.setTitle("my Thermostat Boiler Timer");
		frame4.setSize(300, 200);

		//sets up panel
		panel4 = new JPanel();
		panel4.setBackground(Color.WHITE);
		panel4.setLayout(null);
		frame4.getContentPane().add(panel4);
		frame4.setVisible(true);
		panel4.setVisible(true);

				Calendar calendertimer = new GregorianCalendar();

				//Get the components of the time

				final int timerhour24 = calendertimer.get(Calendar.HOUR_OF_DAY);     // 0..23
				final int timermin = calendertimer.get(Calendar.MINUTE);             // 0..59

				 
		final int MINUTES_IN_HOUR = 60;
		final int NO_OF_HOUR = 24;

		String[] minutesStrings = new String[MINUTES_IN_HOUR];
		for (int i = 0; i < minutesStrings.length; i++)
		{
			minutesStrings[i] = String.format("%02d", i);
		}

		String[] hourStrings = new String[NO_OF_HOUR];
		for (int i = 0; i < hourStrings.length; i++)
		{
			hourStrings[i] = String.format("%02d", i);
		}

		String[] minutesStringsoff = new String[MINUTES_IN_HOUR];
		for (int i = 0; i < minutesStringsoff.length; i++)
		{
			minutesStringsoff[i] = String.format("%02d", i);
		}

		String[] hourStringsoff = new String[NO_OF_HOUR];
		for (int i = 0; i < hourStringsoff.length; i++)
		{
			hourStringsoff[i] = String.format("%02d", i);
		}

		BoilerOn = new JLabel("Boiler Switch On");
		BoilerOn.setBounds(10,10,100,50);
		panel4.add(BoilerOn);

		BoilerOff = new JLabel("Boiler Switch Off");
		BoilerOff.setBounds(140,10,125,50);
		panel4.add(BoilerOff);

		final JComboBox hour = new JComboBox(hourStrings);
		hour.setBounds(10,50,45,25);
		panel4.add(hour);
		hour.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				String hor = (String)hour.getSelectedItem();
				hourOn = Integer.parseInt(hor);
				System.out.print(hourOn);
			}
		});

		final JComboBox minute = new JComboBox(minutesStrings);
		minute.setBounds(60,50,45,25);
		panel4.add(minute);
		minute.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				String min = (String)minute.getSelectedItem();
				minOn = Integer.parseInt(min);
				System.out.print(minOn);
			}
		});

		final JComboBox houroff = new JComboBox(hourStringsoff);
		houroff.setBounds(140,50,45,25);
		panel4.add(houroff);
		houroff.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				String hor = (String)houroff.getSelectedItem();
				hourOff = Integer.parseInt(hor);
				System.out.print(hourOff);
			}
		});

		final JComboBox minuteoff = new JComboBox(minutesStringsoff);
		minuteoff.setBounds(190,50,45,25);
		panel4.add(minuteoff);
		minuteoff.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				String min = (String)minuteoff.getSelectedItem();
				minOff = Integer.parseInt(min);
				System.out.print(minOff);
			}
		});
		System.out.println(hourOn);
		System.out.println(" ");
		System.out.println(timerhour24);

		timerset = new JButton("Confirm");
		timerset.setBounds(155,115,80,40);
		panel4.add(timerset);
		timerset.addActionListener(new ActionListener()
		{public void actionPerformed(ActionEvent event) 
		{
			final Timer timer = new Timer(1000, new ActionListener() {
				public void actionPerformed(ActionEvent e) {
					System.out.println(timerhour24);
					System.out.println(minOn);
					if (timerhour24 == hourOn && timermin == minOn){
						System.out.println("Boiler Status is On");
					} else{
						System.out.println("Boiler Status is Off");
					}

				}});
			timer.start();

		}});


	}

[Campbell Ritchie]

Can't you use the System methods which give the time, from the system clock, and the Calendar method which takes time in milliseconds?