How do I get a Double out of a resultset instead of double?

Question

When working with a JDBC resultset I want to get Double instead of double since this column is nullable. Rs.getDouble returns 0.0 when the column is null.

Answer 1

You can check for wasNull on your ResultSet to find out if the value was null.

Note that you must first call one of the getter methods on a column to try to read its value and then call the method wasNull to see if the value read was SQL NULL.

If you really need a Double afterwards, you can create it from the double returned.

Answer 2

Use ResultSet.wasNull -> http://java.sun.com/javase/6/docs/api/java/sql/ResultSet.html#wasNull%28%29

Basically it works for all primitive types, you first use getDouble, getInt, etc., and then only if the result is 0 you use wasNull.

Answer 3

An alternative to the aforementioned ResultSet#wasNull() is to test ResultSet#getObject() on null so that you can nicely put it in a single line in combination with the ternary operator:

Double d = resultSet.getObject("column") != null ? resultSet.getDouble("column") : null;

instead of

Double d = resultSet.getDouble("column");
if (resultSet.wasNull()) {
    d = null;
}

Answer 4

You could just do:

Double d = (Double) resultSet.getObject("column");

then you don't have to worry if it was null.