Question: I'm writing a library and it has some code like:
public void foo(Object value){
if(value instanceof Date){
...
}else if(value instanceof Calendar){
...
}...
}
The code is supposed can be running on at lease JDK6. So, I have to code and compile on JRE6. But, in case, if a user works on JDK8 and passing a LocalDate/LocalTime object to the method.
How should I handle the case?
LocalDate/LocalTime can't compile on JRE6.
Or, I have to use two version of code? One for JDK6, and another for JDK8?
Answer:
1->Certainly you can't use your JDK 8 types in your JDK 6 code base. However, you may consider using JDK 6 types in your JDK 8 code base. For example, you could consider using 310-backports which basically provides the same set of classes in JDK 8
java.time API for applications running in earlier versions of Java. Unfortunately, this also means changing your JDK8-based APIs to use this backports. –
2->Here's a utility class I use to convert the newer
java.time classes to java.util.Date objects and vice versa:import java.time.Instant;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.ZoneId;
import java.util.Date;
public class DateUtils {
public static Date asDate(LocalDate localDate) {
return Date.from(localDate.atStartOfDay().atZone(ZoneId.systemDefault()).toInstant());
}
public static Date asDate(LocalDateTime localDateTime) {
return Date.from(localDateTime.atZone(ZoneId.systemDefault()).toInstant());
}
public static LocalDate asLocalDate(Date date) {
return Instant.ofEpochMilli(date.getTime()).atZone(ZoneId.systemDefault()).toLocalDate();
}
public static LocalDateTime asLocalDateTime(Date date) {
return Instant.ofEpochMilli(date.getTime()).atZone(ZoneId.systemDefault()).toLocalDateTime();
}
}
)
