如何将对象的sql time转换为java time？

Question

When i run this code it says this:

Error:(43, 31) java: incompatible types: java.sql.Time cannot be converted to java.time.LocalTime

public TrackTime read(int id){

        rs = jdbc.queryForRowSet("SELECT * FROM tracktime where id ='" + id + "'");
        while (rs.next()){
            return new TrackTime (rs.getInt("id"),
                    rs.getDate("date"),
                    rs.getTime("startTime"),
                    rs.getTime("endTime"),
                    rs.getString("licenseType"),
                    rs.getInt("trackNumber"));
        }

        return new TrackTime();
    }

what can be the cause of this error?

Answer 1

As others have said already, this must be because you TrackTime constructor expects arguments of type LocalTime while rs.getTime returns java.sql.Time .

Assuming JDBC 4.2 (or higher; you probably have that), use getObject to retrieve java.time classes like LocalTime and also LocalDate from your result set:

    return new TrackTime (rs.getInt("id"),
            rs.getObject("date", LocalDate.class),
            rs.getObject("startTime", LocalTime.class),
            rs.getObject("endTime", LocalTime.class),
            rs.getString("licenseType"),
            rs.getInt("trackNumber"));

I have taken the freedom of also changing the retrieval of the date, which will probably give you a new compile-time error. But now that you are already using java.time, it may be better to change the TrackTime constructor to accept a LocalDate ?

If your JDBC driver is not yet JDBC 4.2 compliant, consider upgrading.

Answer 2

Your constructor for TrackTime class must be expecting object of class LocalTime where as rs.getTime("startTime") returns java.sql.Time instead of LocalTime and as both are not same hence you get the error.

You can use toLocalTime() method on Time object which returns LocalTime object and this way correct object type would get passed to your constructor and should get away from the error.

So in your code you need to do this,

while (rs.next()){
    return new TrackTime (rs.getInt("id"),
            rs.getDate("date"),
            rs.getTime("startTime").toLocalTime(),
            rs.getTime("endTime").toLocalTime(),
            rs.getString("licenseType"),
            rs.getInt("trackNumber"));
}