Convert Java string to Time, NOT Date

java.sql.Time timeValue = new java.sql.Time(formatter.parse(fajr_prayertime).getTime());

You might consider Joda Time or Java 8, which has a type called LocalTime specifically for a time of day without a date component.

Example code in Joda-Time 2.7/Java 8.

LocalTime t = LocalTime.parse( "17:40" ) ;