How to Efficiently Convert java.util.Date to java.time.LocalDate?

Conversion of java.util.Date to java.time.LocalDate

Problem:

How can you efficiently convert a java.util.Date object to the newer java.time.LocalDate format introduced in JDK 8/JSR-310?

Short Answer:

To achieve the conversion, use the following code:

Date input = new Date();
LocalDate date = input.toInstant().atZone(ZoneId.systemDefault()).toLocalDate();

Java 9 Solution:

A more efficient alternative has been added in Java SE 9:

Date input = new Date();
LocalDate date = LocalDate.ofInstant(input.toInstant(), ZoneId.systemDefault());

Explanation:

Unlike its name suggests, a java.util.Date object denotes an instant in time, rather than a specific date. To convert a java.util.Date to a compatible java.time.LocalDate, the following steps are necessary:

1. Utilize the toInstant() method to obtain an Instant object representing the same instant in time as the Date object.
2. Apply a specific time zone to the Instant object using the atZone() method. The default system time zone (ZoneId.systemDefault()) can be used or a custom time zone.
3. Extract the LocalDate object from the resulting ZonedDateTime object using toLocalDate().

This conversion process accounts for the fact that a java.util.Date doesn't contain timezone information. Specifying the time zone enables the accurate conversion to a specific local date.

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