java - DAO loading data -

i'm trying use dao access data mysql database. want output data array, have java.lang.nullpointerexception. please me solve problem.

playerswindow.java

public static void main(string[] args) {     eventqueue.invokelater(new runnable() {         public void run() {             try {                 playerswindow window = new playerswindow();                 window.frame.setvisible(true);             } catch (exception e) {                 e.printstacktrace();             }         }     }); }  public playerswindow() throws instantiationexception, illegalaccessexception, classnotfoundexception, sqlexception {     initialize(); }     private void initialize() throws sqlexception, instantiationexception, illegalaccessexception, classnotfoundexception {              idao dao = daofactory.getdaoinstance(typedao.mysql);             player mas[] = dao.loadplayers(); //here gives nullpointerexception              object[] headers = { "id", "name", "playing pos", "height", "weight", "nationality", "date birth" };              model = new defaulttablemodel(headers, 0);                model.addrow(mas);             playerstable = new jtable(model); } 

mesqldao.java

public class mysqldao implements idao{      private static string get_players = "select * fbdb.players";     connection con = null;     public mysqldao() throws instantiationexception, illegalaccessexception, classnotfoundexception, sqlexception {         class.forname("com.mysql.jdbc.driver").newinstance();         string url = "jdbc:mysql://localhost/fbdb";         con = drivermanager.getconnection(url,"root","root");      }      public player[] loadplayers() throws sqlexception{          player [] mas = null;         preparedstatement st = con.preparestatement(get_players);         resultset rs = st.executequery();         rs.last();         mas = new player[rs.getrow()];         rs.first();         int =0;         while (rs.next()){             mas[i] = new player (rs.getint(1), rs.getstring(2), rs.getstring(3), rs.getint(4),                     rs.getint(5), rs.getstring(6), rs.getdate(7));              i++;         }         return mas;      } } 

daofactory.java

public class daofactory {     private static idao dao = null;     public static idao getdaoinstance(typedao type){         if(type == typedao.mysql){             if(dao == null){                 dao = new mysqldao();             }             else return dao;             }         return null;     } } 

idao.java

public interface idao {      player[] loadplayers() throws sqlexception;     public boolean saveplayer(player p) throws sqlexception;     public boolean deleteplayer(player p) throws sqlexception;     player editplayer(player p) throws sqlexception; } 

typedao.java

 public enum typedao {         mysql;     } 

exceptions:

java.lang.nullpointerexception     @ fbapp.playerswindow.initialize(playerswindow.java:119)     @ fbapp.playerswindow.<init>(playerswindow.java:91)     @ fbapp.playerswindow$1.run(playerswindow.java:70)     @ java.awt.event.invocationevent.dispatch(unknown source)     @ java.awt.eventqueue.dispatcheventimpl(unknown source)     @ java.awt.eventqueue.access$400(unknown source)     @ java.awt.eventqueue$3.run(unknown source)     @ java.awt.eventqueue$3.run(unknown source)     @ java.security.accesscontroller.doprivileged(native method)     @ java.security.protectiondomain$1.dointersectionprivilege(unknown source)     @ java.awt.eventqueue.dispatchevent(unknown source)     @ java.awt.eventdispatchthread.pumponeeventforfilters(unknown source)     @ java.awt.eventdispatchthread.pumpeventsforfilter(unknown source)     @ java.awt.eventdispatchthread.pumpeventsforhierarchy(unknown source)     @ java.awt.eventdispatchthread.pumpevents(unknown source)     @ java.awt.eventdispatchthread.pumpevents(unknown source)     @ java.awt.eventdispatchthread.run(unknown source) 

the problem returning null in daofactory. here how fix it:

public class daofactory { private static idao dao = null; public static idao getdaoinstance(typedao type){     if(type == typedao.mysql){         if(dao == null){             dao = new mysqldao();         }         }     return dao; } } 

edit: more compact form:

public class daofactory {   private static idao dao = null;   public static idao getdaoinstance(typedao type){     if((type == typedao.mysql)&&(dao == null))dao = new mysqldao();        return dao;   } }