Date Handling in JDBC: java.util.Date vs java.sql.Date
In JDBC, date handling can be particularly confusing due to the existence of multiple Date classes. This article explores the key differences between java.util.Date and java.sql.Date to guide developers on when and why to use each class.
java.util.Date
java.util.Date represents an absolute point in time in milliseconds since the epoch. It is timezone-aware, meaning that it incorporates the current timezone offset when converting the milliseconds to a local date/time.
java.sql.Date
java.sql.Date represents a SQL DATE value, which only contains information about the year, month, and day. It is timezone-independent, meaning that it is not affected by the current timezone offset.
Which One to Use?
The choice between java.util.Date and java.sql.Date depends on the SQL data type of the field being accessed. The following table summarizes the appropriate class to use for each SQL data type:
SQL Data Type | Java Class |
---|---|
DATE | java.sql.Date |
TIME | java.sql.Time |
TIMESTAMP | java.util.Date or java.sql.Timestamp |
For TIMESTAMP fields, both java.util.Date and java.sql.Timestamp can be used, but java.sql.Timestamp provides additional precision by supporting nanoseconds.
Avoidance of Dates
The author recommends against using any of the Date classes directly and instead suggests storing dates and times as plain long values, representing the number of milliseconds or nanoseconds since the epoch. This approach is database-portable and avoids the complexities of the JDBC/Java Date API.
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