Java currentTimeMillis() conversion to seconds not working?

Question

Im trying to convert milliseconds to seconds with System.currentTimeMillis();

System.out.println((int) System.currentTimeMillis() / 1000);

The output is 730750 and increasing by 1. How can i get seconds starting from 0?

**UPDATE: Now i understand the problem and thank you for answering it.

Define "from 0"; what does zero mean in this case? Are you trying to determine an elasped time, for example? — Paul Richter, Dec 08 '14 at 20:38
I am not sure what you are trying to do, but casting to `int` is definitely a problem. You are truncating that long before dividing which gives you a number that is incorrect for any question you might ask. Besides, `System.out.println()` is overloaded for all primitive types. — , Dec 08 '14 at 20:41

score 5 · Accepted Answer · answered Dec 08 '14 at 20:37

5

System.currentTimeMillis() is from January 1, 1970. It will take today's time and subtract it from midnight January 1, 1970. That is why it is so many seconds.

answered Dec 08 '14 at 20:37

brso05

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M A · Answer 2 · 2014-12-08T20:54:16.003

4

From the Javadocs of System.currentTimeMillis():

Returns: the difference, measured in milliseconds, between the current time and midnight, January 1, 1970 UTC.

To start from zero, you need to define a start time. Then you can print the time elapsed after that start time.

long startTime = System.currentTimeMillis();
...
System.out.println((System.currentTimeMillis() - startTime) / 1000);

edited Dec 08 '14 at 20:54

answered Dec 08 '14 at 20:38

M A

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score 3 · Answer 3 · answered Dec 08 '14 at 20:38

3

Since the time is based on the epoch 1.1.1970, you need to base it to the current time.

long start = System.currentTimeMillis();
System.out.println((System.currentTimeMillis() - start) / 1000l);

answered Dec 08 '14 at 20:38

Thomas Jungblut

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Okay i get it now, however my program stops counting at 4-5... Is it from lag? – Mert Karakas Dec 08 '14 at 20:43

score 3 · Answer 4 · answered Dec 08 '14 at 20:41

If you want elapsed time, you can store the start time and then later check the current time. Ex.

int startTimeSeconds = (int) System.currentTimeMillis() / 1000;
// do stuff
System.out.println("Time elapsed: ");
System.out.println(((int) System.currentTimeMillis() / 1000) - startTimeSeconds);

Java currentTimeMillis() conversion to seconds not working?

4 Answers4