NullPointerException и параметр индекса за пределами исключения с использованием MySQL и PreparedStatement

Question

Я получаю эту ошибку при использовании MySQL и не могу понять, как ее исправить. С тех пор, как я переключился с Connection.execute[whatever](), на PreparedStatement, я получал эту ошибку, но не могу ее исправить.

NullPointerException:

guild info space 
[09:51:56 WARN]: java.lang.NullPointerException 
[09:51:56 WARN]: at net.aspace.guilds.Guild.getGuild(Guild.java:56) 
[09:51:56 WARN]: at net.aspace.guilds.command.GuildsInfoCommand.execute(GuildsInfoCommand.java:28) 
[09:51:56 WARN]: at net.aspace.command.CommandNode.onCommand(CommandNode.java:64) 
[09:51:56 WARN]: at org.bukkit.command.PluginCommand.execute(PluginCommand.java:44) 
[09:51:56 WARN]: at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:140) 
[09:51:56 WARN]: at org.bukkit.craftbukkit.v1_10_R1.CraftServer.dispatchCommand(CraftServer.java:646) 
[09:51:56 WARN]: at org.bukkit.craftbukkit.v1_10_R1.CraftServer.dispatchServerCommand(CraftServer.java:632) 
[09:51:56 WARN]: at net.minecraft.server.v1_10_R1.DedicatedServer.aL(DedicatedServer.java:438) 
[09:51:56 WARN]: at net.minecraft.server.v1_10_R1.DedicatedServer.D(DedicatedServer.java:401) 
[09:51:56 WARN]: at net.minecraft.server.v1_10_R1.MinecraftServer.C(MinecraftServer.java:668) 
[09:51:56 WARN]: at net.minecraft.server.v1_10_R1.MinecraftServer.run(MinecraftServer.java:567) 
[09:51:56 WARN]: at java.lang.Thread.run(Thread.java:745) 
[09:51:56 INFO]: Guild space does not exist! 

Индекс параметра из диапазона исключения:

java.sql.SQLException: Parameter index out of range (1 > number of parameters, which is 0). 
[11:11:37 WARN]: at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:963) 
[11:11:37 WARN]: at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:896) 
[11:11:37 WARN]: at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:885) 
[11:11:37 WARN]: at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:860) 
[11:11:37 WARN]: at com.mysql.jdbc.PreparedStatement.checkBounds(PreparedStatement.java:3321) 
[11:11:37 WARN]: at com.mysql.jdbc.PreparedStatement.setInternal(PreparedStatement.java:3306) 
[11:11:37 WARN]: at com.mysql.jdbc.PreparedStatement.setString(PreparedStatement.java:4021) 
[11:11:37 WARN]: at net.aspace.guilds.Guild.getGuild(Guild.java:57) 
[11:11:37 WARN]: at net.aspace.guilds.command.GuildsInfoCommand.execute(GuildsInfoCommand.java:28) 

Вот Guild класс:

package net.aspace.guilds; 

import java.sql.PreparedStatement; 
import java.sql.ResultSet; 
import java.sql.SQLException; 
import java.sql.Statement; 
import java.util.ArrayList; 
import java.util.List; 
import java.util.logging.Logger; 

import net.aspace.chat.Message; 
import net.aspace.guilds.GuildsPlugin; 
import net.aspace.guilds.util.MySQL; 
import net.aspace.util.SimpleCallback; 

import org.bukkit.entity.Player; 
import org.bukkit.plugin.Plugin; 
import org.bukkit.scheduler.BukkitRunnable; 
import org.bukkit.scheduler.BukkitTask; 

public class Guild { 

    public String name; 
    public List<String> members; 
    public int maxPlayers = 3; 

    public Guild(String name) { 
    } 

    public Guild(String name, List<String> members, int maxPlayers) { 
     this.name = name; 
     this.members = members; 
     this.maxPlayers = maxPlayers; 
    } 

    public void addPlayer(final Player p) { 
     final String gName = this.name; 
     new BukkitRunnable() { 

      public void run() { 
       try { 
        PreparedStatement ps = MySQL.getConnection() 
          .prepareStatement("UPDATE PlayerData SET GUILD='?' WHERE PLAYERNAME='?'"); 
        ps.setString(1, gName); 
        ps.setString(2, p.getName()); 
        ps.executeUpdate(); 
       } catch (SQLException e) { 
        e.printStackTrace(); 
       } 
      } 
     }.runTaskAsynchronously((Plugin) GuildsPlugin.getInstance()); 
    } 

    public static void getGuild(final String name, final SimpleCallback<Guild> callback) { 
     try { 
      PreparedStatement ps = MySQL.getConnection().prepareStatement("SELECT * FROM Guilds WHERE GUILD_NAME='?'"); 
      ps.setString(1, name); 
      ArrayList<String> players = new ArrayList<String>(); 

      ResultSet set = ps.executeQuery(); 
      if (set.next()) { 
       String gName = set.getString("GUILD_NAME"); 
       int maxMembers = set.getInt("MAX_MEMBERS"); 
       try { 
        PreparedStatement ps2 = MySQL.getConnection() 
          .prepareStatement("SELECT * FROM PlayerData WHERE GUILD = '?'"); 
        ps2.setString(1, name); 
        ResultSet result = ps2.executeQuery(); 
        GuildsPlugin.getInstance().getLogger().info("select"); 
        while (result.next()) { 
         players.add(result.getString("PLAYERNAME")); 
        } 
        result.close(); 
        callback.execute(new Guild(gName, players, maxMembers)); 
       } catch (SQLException e) { 
        e.printStackTrace(); 
       } 
       set.close(); 

      } 
     } catch (SQLException e) { 
      e.printStackTrace(); 
      callback.execute(null); 
     } catch (NullPointerException e) { 
      e.printStackTrace(); 
      callback.execute(null); 
     } 
    } 

    public static void createGuild(final Player p, final String name) { 
     new BukkitRunnable() { 

      @Override 
      public void run() { 
       try { 
       PreparedStatement ps = MySQL.getConnection().prepareStatement("SELECT * FROM PlayerData WHERE PLAYER_NAME = '?'"); 
       ps.setString(1,p.getName()); 



        //Get player data 
        ResultSet result = ps.executeQuery(); 
        if (result.first()) { 
         //Check if player is in a guild 
         if (result.getString("GUILD") == null) { 
          // TODO Check if guild exists 
          try { 
           //Add guild 
           PreparedStatement ps2 = MySQL.getConnection().prepareStatement("INSERT INTO Guilds (GUILD_NAME,MAX_MEMBERS) VALUES ('?',10)"); 
           ps2.setString(1,name); 
           ps2.executeUpdate(); 
           //Add player to guild 
           PreparedStatement ps3 = MySQL.getConnection().prepareStatement("UPDATE PlayerData SET GUILD='?'" 
             + "WHERE PLAYER_NAME='?'"); 
           ps3.setString(1,name); 
           ps3.setString(2,p.getName()); 
           p.sendMessage(Message.fromString(String.format("&eYou have created and joined the guild &b%s&e!",name))); 
          } catch (SQLException e) { 
           e.printStackTrace(); 
          } 
         } else { 
          //Player is in a guild 
          p.sendMessage(Message.fromString("&cYou are already in a guild!")); 
         } 
        } 
       } catch (SQLException e1) { 
        e1.printStackTrace(); 
       } 
      } 
     }.runTaskAsynchronously(GuildsPlugin.getInstance()); 
    } 

} 

Вот GuildInfoCommand класс:

package net.aspace.guilds.command; 

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

import org.bukkit.command.CommandSender; 
import org.bukkit.entity.Player; 
import org.bukkit.plugin.Plugin; 

import net.aspace.chat.Message; 
import net.aspace.command.CommandNode; 
import net.aspace.guilds.Guild; 
import net.aspace.guilds.GuildsPlugin; 
import net.aspace.guilds.util.GuildsPlayer; 
import net.aspace.util.SimpleCallback; 

public class GuildsInfoCommand<E extends Plugin> extends CommandNode<E> { 

    public GuildsInfoCommand(E plugin) { 
     super(plugin); 
     // TODO Auto-generated constructor stub 
    } 

    @Override 
    public boolean execute(CommandSender sender, String... args) { 
     if (args.length >= 1) { 
      Guild.getGuild(args[0], new SimpleCallback<Guild>() { 

       @Override 
       public void execute(Guild guild) { 
        if (guild != null) { 

         sender.sendMessage(Message.fromString("&b&lGUILD INFO")); 
         sender.sendMessage(Message.fromString("&eGuild name: " + guild.name)); 
         sender.sendMessage(Message.fromString("&eGuild maxmembers: " + guild.maxPlayers)); 
         sender.sendMessage(
           Message.fromString("&eGuild members &7(" + Integer.toString(guild.members.size()) + "/" 
             + Integer.toString(guild.maxPlayers) + ")&e: ")); 
         guild.members.forEach(s -> { 
          sender.sendMessage(Message.fromString("&7- " + s)); 
         }); 
         sender.sendMessage(Message.fromString("&b&lGUILD INFO")); 

        } else { 
         sender.sendMessage(Message.fromString(String.format("&cGuild &e%s&c does not exist!", args[0]))); 
        } 

       } 
      }); 

     } else { 
      if (sender instanceof Player) { 
       Player player = (Player) sender; 
       GuildsPlayer player2 = GuildsPlayer.getPlayer(player); 
       player2.inGuild(new SimpleCallback<Boolean>() { 

        @Override 
        public void execute(Boolean response) { 
         if (response) { 
          Guild.getGuild(args[0], new SimpleCallback<Guild>() { 

           @Override 
           public void execute(Guild guild) { 
            if (guild != null) { 
             sender.sendMessage(Message.fromString("&b&lGUILD INFO")); 
             sender.sendMessage(Message.fromString("&eGuild name: &b" + guild.name)); 
             sender.sendMessage(Message.fromString("&eMember Limit: &b" + guild.maxPlayers)); 
             sender.sendMessage(Message.fromString(
               "&eGuild members &7(" + Integer.toString(guild.members.size()) + "/" 
                 + Integer.toString(guild.maxPlayers) + ")&e: ")); 
             guild.members.forEach(s -> { 
              sender.sendMessage(Message.fromString("&7- " + s)); 
             }); 
             sender.sendMessage(Message.fromString("&b&lGUILD INFO")); 

            } else { 
             sender.sendMessage(Message.fromString("&cYou are not in a guild!")); 
            } 
           } 

          }); 
         } else { 

         } 
        } 
       }); 
      } else { 
       sender.sendMessage(Message.fromString("&cYou must specify a guild name!")); 
      } 
     } 

     return true; 
    } 

    @Override 
    public String getName() { 
     // TODO Auto-generated method stub 
     return "info"; 
    } 

} 

Код для MySQL класса:

package net.aspace.guilds.util; 

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

import org.bukkit.Bukkit; 
import org.bukkit.command.ConsoleCommandSender; 

public class MySQL { 

    public static String host = "****"; 
    public static String port = "****"; 
    public static String database = "****"; 
    public static String username = "****"; 
    public static String password = "****"; 
    public static Connection con; 

    static ConsoleCommandSender console = Bukkit.getConsoleSender(); 

    // connect 
    public static void connect() { 
     if (!isConnected()) { 
      try { 
       con = DriverManager.getConnection("jdbc:mysql://" + host + ":" + port + "/" + database, username, password); 
       console.sendMessage("\247c[\2476Minepedia-System\247c] \247bMySQL-Verbindung wurde aufgebaut!"); 
      } catch (SQLException e) { 
       e.printStackTrace(); 
      } 
     } 
    } 

    // disconnect 
    public static void disconnect() { 
     if (isConnected()) { 
      try { 
       con.close(); 
       console.sendMessage("\247c[\2476Minepedia-System\247c]\247bMySQL-Verbindung wurde geschlossen!"); 
      } catch (SQLException e) { 
       e.printStackTrace(); 
      } 
     } 
    } 

    // isConnected 
    public static boolean isConnected() { 
     return (con == null ? false : true); 
    } 

    // getConnection 
    public static Connection getConnection() { 
     return con; 
    } 
} 

Answer 1

Вам нужно вызвать метод MySQL.connect(), прежде чем пытаться вызвать MySQL.getConnection().

При вызове метод MySQL.getConnection() без MySQL.connect() метода вы не создаете соединение, и, как результат получил NullPointerException при попытке вызвать MySQL.getConnection().prepareStatement...

Вы должны удалить ' символ, потому что SQL парсер интерпретирует их как значение строки и опускает заполнитель ?.

Например:

PreparedStatement ps = 
    MySQL.getConnection().prepareStatement("SELECT * FROM Guilds WHERE GUILD_NAME=?");