Question

I am running this code:

int key = 25;
String query = "Select one, two, three, four, five from myTable where key=?";
List<Map<String,Object>> data = jdbcTemplate.queryForList(query, new Object[]{key});

//one is string, two is int, three is character, four is double, five is string
String one = null;
int two = 0;
char three = '\u0000';
double four = 0.0;
String five = null;

I want to set the five variables above with the values returned in the list. How?

Answer 1

I haven’t actually used JDBCTemplate, but according to the documentation, queryForList will return a List of Maps, with the keys in each Map being the names of the columns.

So to assign those variables from the first returned row:

Map<String,Object> row = data.get(0);
String one  = (String)row.get("one");

//these will not work -- Integer, Double incompatible with String
/* int two     = ((Integer)row.get("two")).intValue();
double four = ((Double)row.get("four")).doubleValue(); */

//correct method
int two     = Integer.parseInt((String)row.get("two"));
double four = Double.parseDouble((String)row.get("four"));

char three  = ((Character)row.get("three")).charValue();
    String five = (String)row.get("five");

As you can see, for the object types, you should just be able to cast. For the primitives, I’ve cast to the object equivalent and then used that object equivalent’s method for getting the underlying primitive (so for int, cast to Integer and then use intValue).