How do you create a sql query of dynamic fields using a final string in VoltDB?

Question

I want to create a sql query of dynamic fields that are decided at runtime, such as:

SELECT some, random, field FROM table WHERE id = ?

Because there is a restriction that you must declare an instance variable SQLStmt:

public final SQLStmt sql = new SQLStmt("SELECT field0, field1 FROM table WHERE id = ?");

Since all fields are hard-coded or else VoltDB will not compile, I cannot set the fields I want to read.

So, How do you create a sql query of dynamic fields using a final string in VoltDB?