Format a UTC date string into a custom date format

Recently I had ran into a task of converting a simple UTC date into a string with a custom format.

This seemed (and actually is) such a simple task, but despite that I took longer than expected to solve this without depending on other dependencies then default Java ones.

Problem

When receiving a UTC date string - e.g. 2021-05-21T00:00:00Z - convert it to the following formats:

1. dd-MM-yyyy - if date is from one of the past years
2. dd MMMM (complete month name) - if date is from the current year

Here’s how I solved…

1 - Date format: dd-MM-yyyy

As an example, this is our use case

GIVEN, we have this utc string date 2021-05-21T00:00:00Z, WHEN, we parse the string, THEN, return 21-05-2021

Solution

First, we need to parse the date and create an instance of Date so we can manipulate the data easier.

val defaultDateFormatter = SimpleDateFormat("yyyy-MM-dd", Locale.getDefault()) 

val parsedDate = defaultDateFormatter.parse(dateToParse)

Secondly, we need to format the parsed date already in Date type, by calling the DateFormat.format(Date) function.

val customDateFormatter = SimpleDateFormat("dd-MM-yyyy", Locale.getDefault())
val formattedDate = customDateFormatter.format(parsedDate)

Finally, grouping both steps this would be the final result:

val defaultDateFormatter = SimpleDateFormat("yyyy-MM-dd", Locale.getDefault()) 

val parsedDate = defaultDateFormatter.parse(dateToParse)

val customDateFormatter = SimpleDateFormat("dd-MM-yyyy", Locale.getDefault())

val formattedDate = customDateFormatter.format(parsedDate)

2 - Date format: dd MMMM

Using the same example, this is our use case for this similar but different problem:

GIVEN, we have this utc string date 2021-05-21T00:00:00Z, WHEN, we parse the string, THEN, return 21 May

This solution will be very similar to the previous one. The only thing that changes is the SimpleDateFormat first String parameter, that refers to our intended date pattern.

Solution

val defaultDateFormatter = SimpleDateFormat("yyyy-MM-dd", Locale.getDefault()) 

val parsedDate = defaultDateFormatter.parse(dateToParse)

val customDateFormatter = SimpleDateFormat("dd MMMM", Locale.getDefault()) // This line is our only change

val formattedDate = customDateFormatter.format(parsedDate)

Conclusion

This is something very simple to do, but it seems there are a lot of other solutions in the internet, using other dependencies (most of them that or not maintained anymore), or using the most recent Android APIs that require you to support a relatively high SDK version.

These solutions also work for any other date types you may want. For more date formats just check Java official documentation.

Let me know if you have any question or suggestion to this small article.

Will be really happy to help!