Implementing Singleton DB Connection in Java

I'm trying to implement a singleton DB connection in Java. I think I have it mostly correct, but when I try to use it in other classes, I keep getting java.lang.NullPointerExceptions.

The error I'm getting is in my FileManipulation class, on the PreparedStatement line where I do conn.PreparedStatement(query); I think conn is being passed as null, but I don't know why or how to fix it.

This is the DB code:

public class dbConnection { static String newLine = System.getProperty("line.separator"); volatile static dbConnection s; public static Connection conn; public static Statement stmt = null; private dbConnection() throws SQLException { // create single instance of DB connection Properties connectionProps = new Properties(); connectionProps.put("user", "root"); connectionProps.put("password", "password"); // port & db name conn = DriverManager.getConnection("jdbc:mysql://" + "localhost" + ":" + "3306" + "/" + "DBNAME", connectionProps); } public Connection getConnection() throws SQLException { return conn; } public static dbConnection getInstance() throws SQLException { if (s == null) { synchronized(dbConnection.class) { if (s == null) { s = new dbConnection(); System.out.print("First DB connection created." + newLine); } } } conn = s.getConnection(); return s; } } 

And here's how I'm trying to use it in my class:

public class FileManipulation { final static String authoritiesTable = "Authorities"; static Connection conn = null; static Statement stmt = null; static BufferedReader reader = null; static String position; static String username; static String password; public static void authorities_check() { try { Scanner scan = new Scanner( System.in ); boolean authentication = false; while (authentication == false) { //get user input System.out.print("Enter your position: "); position = scan.nextLine(); System.out.print("Enter your username: "); username = scan.nextLine(); System.out.print("Enter your password: "); password = scan.nextLine(); if (position != null && username != null && password != null) { authentication = true; } } String query = "SELECT * FROM " + authoritiesTable + " WHERE position = ?" + " AND " + "username = ?" + " AND " + "password = ?"; PreparedStatement pstmt = (PreparedStatement) conn.prepareStatement(query); pstmt.setString(1, position); pstmt.setString(2, username); pstmt.setString(3, password); ResultSet rs = pstmt.executeQuery(); //if user with position, username, and password exists if (rs.next()) { //let them edit the file System.out.println("User authenticated..."); } else { System.out.println("Error: Could not authenticate!"); } scan.close(); } catch(SQLException se) { se.printStackTrace(); } finally { try { if(stmt != null || conn != null) { conn.close(); } } catch(SQLException se) { se.printStackTrace(); } } } public static void main (String[] args) throws SQLException { dbConnection connect = dbConnection.getInstance(); authorities_check(); } }