[MySQL] PreparedStatement NullPointerException

Hi, i am getting an error on this:

Code:java

PreparedStatement sql = connection.prepareStatement("SELECT * FROM `" + table + "` WHERE uuid=?;");

And i don't know why...
This is the "table" variable:

Code:java

private static String table = "flags";

This is the whole code of that block:

Code:java

    public synchronized static boolean dbContainsPlayer(Player player) {
        try {
            PreparedStatement sql = connection
                    .prepareStatement("SELECT * FROM `" + table
                            + "` WHERE uuid=?;");
            sql.setString(1, player.getUniqueId().toString());
            ResultSet resultSet = sql.executeQuery();
            boolean containsPlayer = resultSet.next();
 
            sql.close();
            resultSet.close();
            return containsPlayer;
        } catch (Exception e) {
            e.printStackTrace();
            return false;
        }
    }

Error log:

Code:

[12:18:09] [Server thread/WARN]: java.lang.NullPointerException
[12:18:09] [Server thread/WARN]:    at com.zandor300.defendyourteam.handlers.MySQLHandler.dbContainsPlayer(MySQLHandler.java:57)
[12:18:09] [Server thread/WARN]:    at com.zandor300.defendyourteam.handlers.MySQLHandler.addPlayer(MySQLHandler.java:103)
[12:18:09] [Server thread/WARN]:    at com.zandor300.defendyourteam.listeners.player.PlayerJoin.onPlayerJoin(PlayerJoin.java:28)
[12:18:09] [Server thread/WARN]:    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
[12:18:09] [Server thread/WARN]:    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
[12:18:09] [Server thread/WARN]:    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
[12:18:09] [Server thread/WARN]:    at java.lang.reflect.Method.invoke(Method.java:606)
[12:18:09] [Server thread/WARN]:    at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:292)
[12:18:09] [Server thread/WARN]:    at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62)
[12:18:09] [Server thread/WARN]:    at org.bukkit.plugin.TimedRegisteredListener.callEvent(TimedRegisteredListener.java:30)
[12:18:09] [Server thread/WARN]:    at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:502)
[12:18:09] [Server thread/WARN]:    at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:487)
[12:18:09] [Server thread/WARN]:    at net.minecraft.server.v1_7_R3.PlayerList.c(PlayerList.java:251)
[12:18:09] [Server thread/WARN]:    at net.minecraft.server.v1_7_R3.PlayerList.a(PlayerList.java:138)
[12:18:09] [Server thread/WARN]:    at net.minecraft.server.v1_7_R3.LoginListener.c(LoginListener.java:105)
[12:18:09] [Server thread/WARN]:    at net.minecraft.server.v1_7_R3.LoginListener.a(LoginListener.java:43)
[12:18:09] [Server thread/WARN]:    at net.minecraft.server.v1_7_R3.NetworkManager.a(NetworkManager.java:183)
[12:18:09] [Server thread/WARN]:    at net.minecraft.server.v1_7_R3.ServerConnection.c(ServerConnection.java:81)
[12:18:09] [Server thread/WARN]:    at net.minecraft.server.v1_7_R3.MinecraftServer.v(MinecraftServer.java:713)
[12:18:09] [Server thread/WARN]:    at net.minecraft.server.v1_7_R3.DedicatedServer.v(DedicatedServer.java:283)
[12:18:09] [Server thread/WARN]:    at net.minecraft.server.v1_7_R3.MinecraftServer.u(MinecraftServer.java:576)
[12:18:09] [Server thread/WARN]:    at net.minecraft.server.v1_7_R3.MinecraftServer.run(MinecraftServer.java:482)
[12:18:09] [Server thread/WARN]:    at net.minecraft.server.v1_7_R3.ThreadServerApplication.run(SourceFile:628)

 

When you close the sql connection, do you reopen it?

 

I close my connection when i disable the plugin... And i don't reopen it...

bump

EDIT by Moderator: merged posts, please use the edit button instead of double posting.

 

I've changed it a bit but still getting the same error:

Code:java

    public synchronized static boolean dbContainsPlayer(Player player) {
        try {
            PreparedStatement sql = connection
                    .prepareStatement("SELECT * FROM `" + table
                            + "` WHERE uuid=`"
                            + player.getUniqueId().toString() + "`;");
            ResultSet resultSet = sql.executeQuery();
            boolean containsPlayer = resultSet.next();
 
            sql.close();
            resultSet.close();
            return containsPlayer;
        } catch (Exception e) {
            e.printStackTrace();
            return false;
        }
    }

 

Table being null wouldn't cause this.

Your connection variable has not been set probably.

Can't say without the full class, also don't bump a thread so quickly

 

Code:java

    private static String host = "...";
    private static String port = "3306";
    private static String db = "...";
    private static String table = "flags";
    private static String user = "...";
    private static String pass = "...";
 
    public synchronized static void closeConnection() {
        try {
            if (connection != null || !connection.isClosed()) {
                connection.close();
                plugin.log.info(plugin.prefixc + "Closed MySQL connection!");
 
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
 
    public synchronized static void openConnection() {
        try {
            connection = DriverManager.getConnection("jdbc:mysql://" + host
                    + ":" + port + "/" + db, user, pass);
            plugin.log.info(plugin.prefixc + "Opened MySQL connection!");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
 
    public synchronized static boolean dbContainsPlayer(Player player) {
        try {
            PreparedStatement sql = connection
                    .prepareStatement("SELECT * FROM `" + table
                            + "` WHERE uuid=`"
                            + player.getUniqueId().toString() + "`;");
            ResultSet resultSet = sql.executeQuery();
            boolean containsPlayer = resultSet.next();
 
            sql.close();
            resultSet.close();
            return containsPlayer;
        } catch (Exception e) {
            e.printStackTrace();
            return false;
        }
    }

I have removed some variables... Just so you know

EDIT by Moderator: merged posts, please use the edit button instead of double posting.

 

And where in your code are you calling openConnection();?

 

Your connection is null.
you need test the connection before you try to use it. if the connection is null, re-open it.

Code:java

 
        public synchronized static boolean dbContainsPlayer(Player player) {
 
       if(connection == null){
 
       openConnection();
 
       }
            try {
                PreparedStatement sql = connection
                        .prepareStatement("SELECT * FROM `" + table
                                + "` WHERE uuid=?;");
                sql.setString(1, player.getUniqueId().toString());
                ResultSet resultSet = sql.executeQuery();
                boolean containsPlayer = resultSet.next();
 
                sql.close();
                resultSet.close();
                return containsPlayer;
            } catch (Exception e) {
                e.printStackTrace();
                return false;
            }
        }

 

Thanks! That solved the error!