Question

I have a problem with the code below. Compiler says incompatible types, java.lang.object[][] required but found java.lang.object[].

Anyone have an idea why this is? I’ve found some about generics that gives problems here but no solution to my problem.

Object sqlQuery[][] = null;

List<Object[]> sqlLista = new ArrayList<Object[]>();
   while (resultSet.next()) {
      sqlLista.add(new Object[] { false, resultSet.getString("MMITNO"), null, null, null, null, null } );
   }

sqlQuery = sqlLista.toArray();

edit: I have edited the code above as i see i had made a mistake with the dimensions

Answer 1

The problem is that you’re calling the parameterless overload of toArray(), which returns Object[]. You can’t assign an Object[] to an Object[][] variable.

Now it seems to me that you possibly actually want to make sqlQuery an Object[][][] instead of an Object[][], so that you get one two-dimensional array per entry in the result set. You’d then have:

// Please use this form rather than putting the brackets after the name
// - it keeps all the type information together.
Object[][][] sqlQuery = null; // No point giving it a dummy value

List<Object[][]> list = new ArrayList<Object[][]>();
...
sqlQuery = list.toArray(new Object[0][][]);

However, I’d strongly advise you not to go down this route anyway – encapsulate the “result” concept which is currently just Object[][] in a new type, so you’d have:

Result[] sqlQuery = null;

List<Result> list = new ArrayList<Result>();
...
sqlQuery = list.toArray(new Result[0]);

This will be a lot easier to reason about – even if Result only contains an Object[][].