Question

What would be the simplest way to covert a Set<String> to an argument for Oracle in (?)? I am already using PreparedStatement for that.

Answer 1

You can’t. The query must have one placeholder (?) for each of the elements in the set. And you have to bind every element of the set:

If your set has three elements, your prepared statement must look like this :

String sql = "select foo.* from FOO foo where foo.id in (?, ?, ?)";

and you must iterate through the set and bind each element individually:

int i = 1;
for (String s : setOfStrings) {
    statement.setString(i, s);
    i++;
}