From the JDBC 4.0 final specification (Appendix B)
JDBC Type   | Java Type
CHAR        | String
VARCHAR     | String
NUMERIC     | java.math.BigDecimal
DECIMAL     | java.math.BigDecimal
BIT         | boolean
BOOLEAN     | boolean
TINYINT     | byte
SMALLINT    | short
Note that the CHAR column type is mapped to String in the JDBC specification so for a CHAR(1) column you get and set in Java using:
// set char in PreparedStatement
preparedStatement.setString(1, String.valueOf(myChar));

// get char from ResultSet
char c = rs.getString(1).charAt(0);