With regards to JSR-310 another project of interest might be threetenbp.
JSR-310 provides a new date and time library for Java SE 8. This project is the backport to Java SE 6 and 7.
In case you are working on an Android project you might want to checkout the ThreeTenABP library.
compile "com.jakewharton.threetenabp:threetenabp:${version}"
JSR-310 was included in Java 8 as the java.time.* package. It is a full replacement for the ailing Date and Calendar APIs in both Java and Android. JSR-310 was backported to Java 6 by its creator, Stephen Colebourne, from which this library is adapted.