It says you're using
comboBox_1 as a type, but you haven't declared it as a type. And you have:
I think you meant to use the
addItem() method of JComboBox here.
By the way can I suggest you use the try-with-resources statement for your
JDBC code? It would look more like this:
As you can see, it takes care of all the tedious finally-clauses and resource-closing for you. I also removed the code where you caught an exception and did nothing but throw the exception. There's no point in doing that because the exception is going to be thrown anyway.