java - Strange NullPointer Exception in main -


i'm trying exercise java book. code comes , have not added code besides setting path database. i'm on osx, had install apache derby. everytime build , run program this:

derby has been started.  product list: bvbn    murach's beginning visual basic .net        $49.50 cshp    murach's c#                                 $49.50 java    murach's beginning java                     $49.50 jsps    murach's java servlets , jsp              $49.50 mcb2    murach's mainframe cobol                    $59.50 sqls    murach's sql sql server                 $49.50 zjcl    murach's os/390 , z/os jcl                $62.50  exception in thread "main" java.lang.nullpointerexception first product: @ dbtesterapp.printproduct(dbtesterapp.java:117) @ dbtesterapp.printfirstproduct(dbtesterapp.java:66) @ dbtesterapp.main(dbtesterapp.java:16)   java result: 1   build successful (total time: 2 seconds)

i'm confused why exception keeps happening. don't seem find wrong 'main' code (see below) , feel i've tried everything. clue causing this? 

import java.sql.*;  public class dbtesterapp { private static connection connection = null;  public static void main(string args[]) {     // connection , start derby engine     connection = murachdb.getconnection();     if (connection != null)         system.out.println("derby has been started.\n");      // select data database     printproducts();     printfirstproduct();     printlastproduct();     printproductbycode("java");      // modify data in database     product p = new product("test", "test product", 49.50);             insertproduct(p);     printproducts();      deleteproduct(p);     printproducts();      // disconnect database     if (murachdb.disconnect())         system.out.println("derby has been shut down.\n"); }  public static void printproducts() {     try (statement statement = connection.createstatement();          resultset rs = statement.executequery("select * products"))     {                     product p = null;          system.out.println("product list:");         while(rs.next())         {             string code = rs.getstring("productcode");             string description = rs.getstring("description");             double price = rs.getdouble("price");              p = new product(code, description, price);              printproduct(p);         }         system.out.println();     }     catch(sqlexception e)     {         e.printstacktrace();  // debugging     } }  public static void printfirstproduct() {     product p = null;      // add code prints record first product in products table      system.out.println("first product:");     printproduct(p);     system.out.println(); }  public static void printlastproduct() {     product p = null;      // add code prints record last product in products table      system.out.println("last product:");     printproduct(p);     system.out.println(); }  public static void printproductbycode(string productcode) {     product p = null;      // add code prints product specified code      system.out.println("product code: " + productcode);     printproduct(p);     system.out.println(); }  public static void insertproduct(product p) {     system.out.println("insert test: ");      // add code inserts specified product database     // if product specifed code exists, display error message      printproduct(p);     system.out.println(); }  private static void deleteproduct(product p) {     system.out.println("delete test: ");      // add code deletes specified product database     // if product specified code doesn't exist, display error message      printproduct(p);     system.out.println(); }  // use method print product object on single line private static void printproduct(product p) {     string productstring =         stringutils.padwithspaces(p.getcode(), 8) +         stringutils.padwithspaces(p.getdescription(), 44) +         p.getformattedprice();      system.out.println(productstring);  } }

this sequence of code produce npe product phas not been instantiated:

product p = null;  system.out.println("first product:"); printproduct(p);

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