SimpleDateFormat returns wrong number of days

I need to get the number days, hours, minutes, seconds from a long value. But I am getting wrong number of days from a following code.

public static String formatTimeUTC(long value, String pattern) {
    final SimpleDateFormat format = new SimpleDateFormat(pattern, Locale.US);
    format.setTimeZone(TimeZone.getTimeZone("UTC"));
    Date date = new Date(value);
    String formatString = format.format(date);
    return formatString;
}

When I pass 106988550 and "dd:HH:mm:ss" to this method, I am getting “02:05:43:08”

Expected actual answer is : “01:05:43:08”.

I don’t know where it is wrong and how I can achieve the actual answer.

Answer

The Answer by Hochschild is correct. You are handling a span of time as a date-time, liking mixing apples with oranges.

java.time

The java.time classes supplant the troublesome old date-time classes. Makes easy work of this.

You do not actually explain, but I am guessing your number is a count of elapsed milliseconds.

long input = 106_988_550L ;

We represent that as a Duration.

Duration d = Duration.ofMillis( input );

We can represent that value as a string formatted with a subset of standard ISO 8601 format for durations, PTnHnMnS.

String output = d.toString();

PT29H43M8.55S

See live code in IdeOne.com.

In Java 9 and later, you can access each component of that value by calling the to…Part methods such as toDaysPart, toHoursPart, etc.

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About java.time

The java.time framework is built into Java 8 and later. These classes supplant the troublesome old legacy date-time classes such as java.util.Date, Calendar, & SimpleDateFormat.

The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.

To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.

Where to obtain the java.time classes?

• Java SE 8 and SE 9 and later
  • Built-in.
  • Part of the standard Java API with a bundled implementation.
  • Java 9 adds some minor features and fixes.
• Java SE 6 and SE 7
  • Much of the java.time functionality is back-ported to Java 6 & 7 in ThreeTen-Backport.
• Android
  • The ThreeTenABP project adapts ThreeTen-Backport (mentioned above) for Android specifically.
  • See How to use….

The ThreeTen-Extra project extends java.time with additional classes. This project is a proving ground for possible future additions to java.time. You may find some useful classes here such as Interval, YearWeek, YearQuarter, and more.