import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

// Extends java.sql :~ describes connections to Oracle db
class dbConn {

    Connection conn;
    Statement stmt;
    ResultSet rs;
    String conString;
    String sqlString;

    void dbConn() {
        try {
            Class.forName("oracle.jdbc.driver.OracleDriver");
            conn = DriverManager.getConnection(conString);
        } catch (ClassNotFoundException | SQLException e) {
            e.printStackTrace();
        }
        if (conn != null) {
            System.out.println("Connection established, database uplink is online.");
        } else {
            System.out.println("Connection failed, please check database status.");
        }
    }
}

import javax.swing.*;

public class CaseMoverUI {
    void testUI(){

        // Create a new JFrame container
        JFrame jfrm = new JFrame("CaseMover");
        jfrm.setSize(550, 450);
        jfrm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        JComboBox jbox = new JComboBox();
        jfrm.add(jbox);
        jfrm.setVisible(true);
        SwingUtilities.invokeLater(new Runnable(){
            public void run(){
                new CaseMoverUI();
            }
        });
    }
}

public class sqlCaller {
    public static void main(String args[]){
        //instantiate db object and pass values to the constructor
        dbConn db = new dbConn();
        db.conString = "jdbc:oracle:thin:system/jamie123@127.0.0.1:1521:xe";
        db.sqlString = "SELECT true FROM dual";

        db.dbConn();
        CaseMoverUI ui = new CaseMoverUI();
        ui.testUI();
    }
}